Lucy in the sky with deadly radiation 5: strangest sky ever!

[king of nowhere]

Part 0: Introduction and ship

I was worried I'd run out of grand tour challenges to try after the real solar system, luckily the modding community is doing a good job.

One year ago I found mention of the whirligig world planetary system, which I found very intriguing.

Quote

Around 1300 years ago, explorers from the far off planet Kerbin left their home to colonize other star systems. One such ship embarked on a journey to Kerbmun, an oxygenated moon in the Kaywell star system. There was just one problem. They hadn't counted on Mesbin being much wider than expected.

Unable to correct their course due to piloting error, the U.S.C. Manifest Destiny crashed into the massive, 70 Kerbin Mass planet Mesbin. Luckily, Mesbin spins. Once every twenty eight minutes it completes a rotation, and the centripetal effect pushes the equator outwards and negates some of the gravity. The 13 gees of gravity at the poles is reduced to a tad under 1.3 gee at the equator.

The payload of the ship survived, but the engines and fuel tanks were reduced to a lot of metal rubble along the surface. Unable to find somewhere else to go, the survivors buried themselves underground and set up a stable ecosystem and environment. It took nearly two millenia, a few wars, and the re-invention of the steam engine, but eventually the colony was sufficiently industrialized to start looking up again.

Besides this unconventional starting planet, the whirligig system also includes a double star in close orbit, a hot Jupiter, sub-moons, trojan orbits, eccentric orbits. Seems a perfect next target for another grand tour, so I marked it on my to-do list for after I was done with the real solar system. Which I finished in january, so I took my time for this one.

Part of the difficulty was deciding exactly what I would do. Starting from the very premise of those missions: kerbalism is not compatible with this planetary pack.

Kerbalism has always been what added spice to a grand tour. With an isru ship, a grand tour is really no more difficult than a handful of individual missions. Not much of a challenge. Having your ship slowly breaking down while you're at it, that is what made things interesting. On the other hand, I gradually learned how to navigate the difficulties of kerbalism so that by the end they were mostly irrelevant - my last grand tour had no issues with reliability or life support supplies, and only once radiations really created suspence. On the plus side, lag would be a lot more manageable, so I'm not really unhappy for being unable to use kerbalism.

But this means I need to find some other challenge to add.

So I decided, despite the lack of kerbalism, I'm going to pretend I still have to take care of life support and hard isru. The most relevant decision is that I will only refuel on planets with an atmosphere; here I'm pretending I'm gathering CO₂ from the atmosphere to make new fuel. Otherwise, whirligig world has small moonlets scattered everywhere for a cheap refueling which would make it too easy. On the other hand, I'm not trying to build redundancies; I can enjoy some more freedom in design.

Initially, I also decided I wanted to try making this a fully reusable mission. However, there are two planets bigger than Eve; I spent some time trying to build a Eve ssto, and I got told that you need a bunch of exploits to make frictionless parts to make it work - which makes it bug exploiting in my book, so I basically lost interest in trying to make an Eve ssto. But even if I could make one, Derbin and Valyr have 30% more gravity and require an additional 2 km/s to orbit, so they'd be impossible to ssto anyway. So I changed the condition as "fully reusable except for the Derbin and Valyr landers".

0.1) Boundless mothership

Spoiler

Within a few weeks of playing ksp, I decided I wanted to make a magnificent mothership capable of going anywhere and doing anything. Fully reusable, with lots of deltaV, room for a massive crew, and a large array of shuttles for specialized tasks. And it would have been called Boundless.

I never built Boundless because the project included an Eve ssto, which I was never capable of building. But now that I gave up on ever trying, I feel free to use the name.

Boundless without its shuttles

I don't need a huge solar array, but I'm pretending I'm still using kerbalism, and I'm not using nuclear reactors this time, so I just put it there for the sake of pretending. And for beauty. Even though it doubles the ship's part count.

But I also decided I wanted a ship with strong aerobraking capabilities. Whirligig world has a lot of atmospheric planets, being able to aerobrake from high speed is important. Ok, not so much when your ship has 9 km/s, but I wanted it, and I wanted some excuse to add some piece of cool engineering to what would otherwise be nothing but a glorified fuel tank. So, the solar array can be retracted and enclosed inside cargo bays, the engines can be covered by nose cone bays (part of the near future pack) and all the shuttles are mounted on top, protected from airflow. Unfortunately, Boundless in this configuration has very low drag, and despite its survivability it was failing at the "braking" part of aerobraking. So I added some thermal shields mounted as parachutes to increase drag.

Boundless in aerobraking configuration

Sequence of the opening of the solar panels

An older version of the solar array. I played a few weeks with this, but I realized it was getting bent over time, so I reworked in favor of a more stable model

Boundless pushing its aerobraking to the limit on Kerbmun, a Kerbin-like world

I included a lot more living space than actually needed; as I'm pretending to be using kerbalism, I am using that in place of the heavy greenhouses and water tanks . It's still a lot lighter than actual greenhouses and water tank, so I made Boundless smaller than my previous motherships.

I was very indecisive on whether I'd use nuclear or chemical engines. The thing is, nuclear engines are way too overpowered for a stock-like system. Then again, whirligig world uses stock proportions - meaning you can get to most interplanetary destinations with 1 km/s - but it has a few planets and moons very close to their parent body, requiring huge amounts of deltaV to reach. The cake goes to Ammenon, a small planet orbiting close to a minor star orbiting the main star of the system; a Hohmann transfer from its closest neighboor requires 5 km/s for an intercept (which can possibly be avoided by gravity assist) and 10 km/s of intercept speed - which cannot be avoided. I decided I'd try to make a reusable mission to Ammenon, and it that makes Boundless overpowered for anyting else, so be it.

0.2) Cigar small lander

Spoiler

Next piece is a small lander for the minor planets.

Cigar lander, side view

Without kerbalism to force redundancy and heavy radiation plating, I decided to make something a lot smaller than usual, at only 4 tons. It doesn't have much thrust or deltaV, but it's enough for whirligig world; all planets significantly bigger than Mun have an atmosphere, so they will get a different lander. I also got to use the airplane crew pod, which has the best IVA view - can't be used in kerbalism, it would cause the whole ship to become depressurized. I also got to include RCS thrusters for easier docking, something I never did in kerbalism because of the additional issues of redundancy and part count.

I eventually removed the light from the front because it was blocking the view too much.

0.3) Arrowhead (stock version), atmospheric space plane

Spoiler

For the many atmospheric worlds I needed some kind of propeller plane. I decided to use the Arrowhead spaceplane, from the A'Tuin grand tour, because I liked that vehicle.

Without kerbalism, I made some rework to remove redundant parts, reducing its mass by 20%

Arrowhead, top view

Arrowhead, detail of the cargo bay and propellers bay

Arrowhead is fully capable of going ssto on Kerbin, making it adequate to orbit every planet in the whirligig world pack - except Derbin and Valyr.

Landing, on the other hand, was a bigger issue; some of those planets have too thin atmospheres, making Arrowhead incapable of flight. I solved that problem by temporarily strapping a few parachutes on the front of the plane, allowing it to land like a rocket.

I decided to make an exception and leave the RTGs in this case; solar panels would have marred the profile of the plane.

0.4) Traveler taxi

Spoiler

Having two landers of very different masses, I decided to keep a modular approach to the taxi: a core taxi module, relatively light, to carry around the small lander cheaply, and an additional fuel tank module, to carry the bigger lander.

Traveler, heavy configuration

Traveler, light configuration

Traveler is also optimized for aerobraking, though that was unnecessary.

It's surprising how little I have to say about ships when I don't have to discuss life support, redundancy and radiation protection.

0.5) Ice Cream Cone, refueling vehicle

Spoiler

I decided to use an architecture similar to the DREAM BIG mission, with a dedicated ship to land on atmospheric planets to make fuel. Since I have no issues with breakable parts, this time I don't need four, one suffices.

Ice Cream Cone in the VAB

Ice Cream Cone, fully deployed

On a Duna-like planet, it can carry up 100 tons of fuel per trip. Of course, on a bigger planet I can reduce the amount of liquit fuel to increase deltaV.

I probably gave Ice Cream Cone more thrust than it actually needed; I wanted it to be able to refuel also on some bigger planets, but I doubt I will have the patience to perform refueling operations when every trip only carries up 20 tons of fuel or so.

Notice the shielded small docking port; I don't even remember which expansion it comes from.

0.6) Phoenix heavy landers

Spoiler

For the two superEve planets, I needed something with propellers to clear the atmosphere, plus a lot of staging to provide the almost 7 km/s required after that.

I also decided I wanted to include something nice. Not just a descent/ascent vehicle, but something with a living space that could work as a mobile science base for a prolonged time. So, a plane with a crew habitat that could be dropped to get a lighter plane, that would then drop the wings to get the final rocket. With a relatively low mass.

The hardest part was balancing everything so that the center of mass and center of lift were correctly positioned at every step.  Protecting this baby from high speed atmospheric reentry at 5 km/s was also no small feat. I called it Phoenix for all the flames involved in the process.

Phoenix, with the thermal shields and umbilical connecting it to the mothership

Phoenix, as it lands on a planet, ready to fly around and explore

Phoenix, rocket part. TWR (RSP in my italian game) is relative to Derbin, roughly 2.17 g

0.7) Redentor small probes

Spoiler

As usual, I keep my tradition of carrying small exploration probes even though they are not necessary at all.

Boundless, fully assembled

Boundless, side view

Boundless, using the rockets

Boundless, seen from Cigar while docking near Graymun

As above, a bit closer

The solar array, seen by a spacewalking kerbal

The objective is to perform a grand tour of the whirligig world system, while refueling only on atmospheric planets, pretending to have to care about life support (as a rule of thumb I assume 50 years for the mothership, 1 year for the taxi, 30 days for landers). I will try to land everywhere except Derbin and Valyr in a reusable manner, though I'm not sure I can tackle Ammenon and its 30 km/s round trip. In that case, I confess I brought some xenon tanks; I hope I won't have to use them, but just in case...

A comprehensive map of the Kaywell system, highlighting the orbital relations and the general characteristics of the various celestial bodies

Edited July 5, 2023 by king of nowhere

[king of nowhere]

Part 1: Climbing out of the gravity well

Orbiting Mesbin is cheap thanks to its rapid rotation, but raising orbit around Mesbin is very expensive. Boundless slowly gets out of this deep gravity well while visiting the inner moons of Mesbin.

The relative positions of the inner moons. Statmun and Thresomin are smaller than Gilly, while Graymun is Mun-sized

From low orbit it takes roughly 300 m/s to raise apoapsis to Statmun, an additional 1600 m/s to raise it to Thresomin, and finally 650 for Graymun

1.1) Launching Boundless

Spoiler

Mesbin is a truly massive planet. Orbital speed for a low orbit is over 10 km/s, a lot higher than Jool - Mesbin is slightly lighter than Jool, but a lot smaller, so a low orbit is much closer to the center of the planet. On the plus side, the rapid rotation of the planet means you already have 8.5 km/s of lateral speed even on the surface. You can see the rotation of the sky without time warping. Also, there is no atmosphere except on the polar regions. This makes orbiting Mesbin significantly easier than orbiting Kerbin, depite a 30% bigger surface gravity. Landing, on the other hand, is a grueling ordeal reminescent of Tylo. Good thing I'm not planning to land on Mesbin.

To save time on launches, I use the well-established procedure of launching the mothership with the shuttles already docked in place. All of them except for Ice Cream Cone and Arrowhead, because the shielded small docking port cannot be docked in the VAB.

Boundless on the launchpad

From one of the cupolas, looking at the VAB

From the opposite cupola, looking at the magnificent desolation of Mesbin. The reddish knob on the horizon is the geostationary moonlet Statmun

The rearward facing cupola, still enclosed in the nose cone cargo bay

View from one of the crew cabins in the middle, overlooking a Phoenix

And from Cigar

Yes, with Boundless I went a bit overboard in trying to get good IVA views. I'm no longer limited to cramming all my living space inside a shell of fuel tanks for radiation protection, I tried to build something that would look nice.

Ignition

Starting gravity turn immediately, and opening nose cones

As there is no atmosphere on Mesbin's equator, you can make a steep gravity turn and launch low. You also can use the NERVs immediately on the launchpad, but I preferred to only activate them later because the opening of the nose cones interfered with the launch stabilizers.

Views from the rearward cupola. Every space agency should get one. Well, Spacex has put a camera in that spot, so it counts

I had to use this weird asymmetric configuration for my boosters to fit into the space left by the opening nose cones

Detaching the boosters also caused a lateral section of Boundless to get detached. This turned out to be a tricky procedure; I basically had to detach each booster one by one to avoid overstressing the ship

Detaching the boosters, this time successfully

Boundless finishes circularization on its own power now, leaving behind the discarded boosters. A good view on Kerbmun from this cupola; the smaller dot on its right is probably Derbin

Now I have to launch and dock separately Ice Cream Cone and Arrowhead. Ice Cream Cone has low deltaV as a tanker, but as long as it carries only its own fuel it has way more than enough to orbit Mesbin.

Launching Ice Cream Cone

And docking it to Boundless

Docking is very comfortable with a powerful RCS system. I could have saved roughly one ton of mass by skipping it, but since I will have to make dozens of dockings with this thing, I decided to go for luxury. I regret not putting some floodlight in front.

As for Arrowhead, it has way more than enough deltaV to orbit, its problem is that its engines do not point up while on the ground. It's supposed to fly up and maneuver while in the air, but there's no air on Mesbin. The solution is to launch it from a ramp pointing up. But you've seen the surrounding of the kerbal space center are completely flat as far as the eye can see, where do I find an upward slope around here?

Here it is, problem solved

For a brief moment Arrowhead is jumping, and I use that opportunity to point up and ascend like a proper rocket

Arrowhead docked; actual picture from later in the mission, as I didn't take one after launch; that's why here Arrowhead is docking near Traveler, while in the pic underneath it's near Ice Cream Cone

I also gave Arrowhead a couple RCS thrusters; the thing is, docking backwards amid a jungle of other closely fitting shuttles is very difficult. Those thrusters can then be removed by EVA construction and stored inside Arrowhead's crew pod, to keep a better aerodinamic profile.

Also notice how the shield on the docking port extends past the docking port itself, creating some issues with docking. For Arrowhead, I solved it by putting its docking port on a side of a bigger part, so the shield can lean out. For Ice Cream Cone, I placed a small fuel tank under the docking port on Boundless to act as spacer. I had to scrap the first launch because I didn't consider this factor and couldn't dock those ships.

Boundless, fully assembled

Four shuttles are on top; from the left, Cigar, Traveler, Ice Cream Cone, Arrowhead. The Redentor probes are hanging laterally from the high towers supporting the solar array; it does not look good, but the lower thermal shields are protecting them from direct airflow during aerobraking. The two Phoenix are front and back, they are not protected during aerobraking because they are already made for high thermal resistance.

Status; of course without kerbalism to add life support resources there's not much point to show one. Here I wanted to show that I still got over 1000 parts

Just a minor note, Boundless was initially called Kalimba, and that's why it will be named thusly in this picture and others afterwards, until I decided I liked Boundless better. I'm not going to retroactively edit all the screenshots.

1.2) Statmun the bizarre

Spoiler

Quoted from the whirligig world page:

Quote

Statmun is extremely dense and nonetheless still below the roche limit. However, it's also a huge chunk of nearly monolithic iron, and spinning fast enough that its surface gravity across its equator is negative anyway, so that's hardly a problem. Statmun contains almost no volatiles, and thus can NOT BE MINED FOR ORE.

So, Statmun is a large asteroid (3 km radius) orbiting just a few hundred kilometers above the surface, and it spins so fast objects on the equator will be launched outward. Quite the interesting place. I would like to make a circumnavigation of it, using a robot with claws for feet, to grab the surface. But it would be extremely slow; maybe one day when I really have nothing better to do.

Statmun is close enough to low orbit that I can send Cigar alone.

Detaching Cigar from Boundless

I had already raised Boundless apoapsis to Statmun level, since I had to do it anyway. Cigar only needs to sincronyze orbits and pay the intercept deltaV.

For a total cost of 350 m/s

Leaving Boundless. You will forgive me for including as many scenical views of my mothership as possible

Approaching Statmun. Funny thing, I'm still outside of its sphere of influence, which has a 9 km radius above the surface.

Just inside the sphere of influence. Also, here you can better appreciate the twin stars Kaywell and Limnel

From this perspective it looks like Kerbmun is about to get crushed between Statmun and Mesbin

Landed near the equator! Notice how the engine is working at low power to counteract the centrifugal force

Yep, parking on Statmun equator is quite expensive. At least the engine stays on even when the kerbal is doing a spacewalk, so I can keep the lander parked in the time needed to collect science and take pictures.

Playing golf on the surface. Actually the ball should start floating and get lost in an escape trajectory without even being hit

A couple pic to show the centrifugal force. They are taken 12 seconds from each other, you can see how Cigar is picking up speed; also how it doesn't have an apoapsis, meaning it's in escape trajectory

And here I landed near the poles, where you can at least stay on the surface

The view is amazing. Mesbin is an intimidating wall in front of you, making you fully realize that you're suspended in the sky

I decide to take a drive to the nearest biome. Very slowly, of course, but I did travel one km by wheels on this tiny moonlet

More amazing shoots. Statmun is  breathtaking

Leaving Statmun

And returning to Boundless

1.3) Tiny Thresomin

Spoiler

Quoted from the whirligig world page:

Quote

Two of Mesbin's three minor moons, Thresomin and Troymin, are designed to exist as propellant mines for setting up infrastructure. Whirligig World rewards building infrastructure

That's exactly why I had to put a limitation on refueling only on atmospheric planets; with 9 km/s and the ability to refuel on every tiny rock, there would be no challenge. Also, a body that small wouldn't have many volatiles to make fuel either. Even if it had some residual water left, it would not last much once used regularly.

Anyway, Thresomin is just that; a tiny rock halfway between Statmun and Graymun, placed because it would make for convenient refueling.

I need to raise apoapsis all the way to Graymun, Thresomin is just a stop along the way.

It takes 1600 m/s to raise apoapsis from Statmun level to Thresomin level

Boundless has low thrust, so the apoapsis raising is done slowly over multiple orbits

More nice scenery

By complete chance, Boundless passed within a few km of Statmun during one such maneuvers

It took a while; a downside of fast orbits is that the time available to burn with small cosine losses is short, so I could push little more than 100 m/s at every orbit. But eventually I raised apoapsis to Thresomin.

Now, obviously there's no reason for Boundless to get captured on Thresomin. It would only entail an expensive periapsis-raising maneuver. But it's going to be cheaper to send Cigar from this orbit.

This time intrcept speed is high, over 1500 m/s - and just as much to return to Boundless afterwards. A downside of tiny moons is that they provide no Oberth effect. Cigar doesn't have enough fuel, it needs to be accompanied by Traveler.

Cigar docks with Traveler

Traveler fully deploys its solar array

The 1500 m/s of intercept, split that way to achieve the right orbital time to meet Thresomin. I only loaded half fuel in Traveler, it's more than adequate

Thresomin. At 2 km equatorial radius, it's even smaller than Statmun; I'm still outside of the SoI

First view from inside the sphere of influence. And from inside the ship too

Landed, and moving on the surface

Since Thresomin is so small, and relatively flat, the first time I landed here I decided to circumnavigate the moon.

That time I had a defective solar array on Boundless, and I was eventually forced to replay the mission from start. But the circumnavigation remains. The second time I just landed, planted a flag and left.

Everything is better with comets! So long as they're not hitting you, at least

The belt of flags planted around Thresomin

Traveler and Cigar rejoining Boundless, seen from one of Boundless cupolas

And this is seen from Cigar's cabin, with a striking detal on Mesbin surface

1.4) Aptly-named Greymun

Spoiler

Now Boundless has the final leg of apoapsis raising; the target is Greymun. Unlike the other moonlets, Graymun is slightly bigger than Mun, so it's big enough to provide gravity assists; I'm using it to push my orbit up to Kerbmun, where I'll make a temporary stop.

A last 650 m/s to reach a useful target

Boundless (still named Kalimba here) takes the first gravity assist; it has a minuscule effect on apoapsis, but it does raise periapsis significantly (red line)

According to how gravity assists work, you leave the target body at the same speed (relative to it) that you came. I'm now coming to Graymun on a perfect Hohmann trajectory, that minimizes my intercept deltaV. And I'm using Graymun to raise periapsis, because the biggest effect of any maneuver is on the opposite side of the orbit. But then, if my apoapsis stayed the same and periapsis increased, that would result in a lower intercept speed on Graymun - which cannot be, because intercept speed must remain the same. Hence this gravity assist also gives a slight apoapsis raising; just enough to put me out of an ideal Hohmann, keeping intercept speed the same. In general, I'm about to perform a long sequence of gravity assists on Graymun, slowly raising my orbit. Good thing Graymun has a fast orbit, so I don't have to worry about food supplies.

But what about landing? Since we established that in any flyby Boundless will have the same intercept speed, I'm also using those flybys to drop and pick up the lander.

Cigar and Traveler got detached from Boundless, they will get captured on Graymun for 1400 m/s. It's less than the capture speed on Thresomin because Graymun has some Oberth effect

Capture burn on Graymun

While Boundless is zipping past on its high speed intercept

With Cigar safely in orbit, first priority is making arrangements for Boundless next flyby. A small course correction at periapsis will fine-tune it, in 1 day 5 hours (red trajectory)

So I have 1 day 5 hours to land before Boundless will come back to pick up Cigar. It's a lot of time.

Cigar and Traveler in Graymun orbit

Little trivia: even though Kaywell and Limnel are two stars in a binary system, the game engine is not equipped to deal with that. So while both starts make light, only Kaywell can power up solar panels. When Limnel is passing in front of Kaywell, solar panels stop working. As I had to restart the mission, I took the chance to install bigger batteries to deal with the periodic blackout.

Cigar prepares to land

Cigar landing sequence looks a bit silly, but it does its job

I decided to drive around Graymun. I want to experience those celestial bodies, not just plant a flag on them as fast as possible

More driving on Graymun

Cigar is a decent rover, but not great. It's got a very narrow base, and even though it relies on reaction wheels to keep upright, it's not a perfect system. Therefore, it's significantly more fragile than other rovers I made. Well, it's small and light, can't pretend too much.

Just like Arrowhead, it has the engine in the back, aligned with the ground, so it must find a natural slope to launch. That's not a problem. What are the chances that I'm not going to find any eastward facing slope on a planet?

Cigar picking up speed on a slope to return to orbit

As I was flying to orbit, I spotted this arc. Looks like Graymun was made using Mun's model, so it has the same anomalies. Can't confirm with kerbnet because kerbnet does not work in this planetary pack

The planned flyby of Boundless

It may not be clear from the picture, but in this case Boundless will arrive to Graymun retrograde compared to Cigar. It would be very expensive to rendez-vous. Not a big deal, I'll wait the next.

Boundless prepares for its third flyby of Graymun. By now the effect on both periapsis and apoapsis is getting noticeable

The rockets seen from another crew cabin on Boundless

All is ready for the rendez-vous of Cigar on the next flyby

To rendez-vous from an escape trajectory, Cigar must pass near Boundless periapsis at the same time as Boundless. You can see I raised apoapsis a bit to syncronize orbits for this passage. It's still not a close passage (intersection 2, 156 km), but that's because it will be a very fast passage and Traveler has low thrust. So I made sure to put Cigar+Traveler well ahead of Boundless; this way they have a headstart and can accelerate gradually while Boundless catches up.

Indeed, here Boundless is coming, and Traveler is accelerating

And now the exit trajectories look similar

And finally here, both Traveler and Boundless are out of Graymun's SoI but close enough and on similar enough trajectories that it's easy to rendez-vous them in Mesbin orbit

Back to Boundless

1.5) Greymun is your friend: the route to Kerbmun

Spoiler

It would take another km/s to raise apoapsis from Graymun to Kerbmun, but I'm going to save that by gravity assist. Those assists from Graymun are invaluable not only for raising apoapsis, but for raising periapsis too, resulting in a more gentle intercept on Kerbmun. Kerbmun is very similar to Kerbin (just 6% more surface gravity), and while Boundless is reinforced for aerobraking, a high speed intercept on a Kerbin-like planet is beyond its capabilities. So, the mod builder placed Thresomin to refuel, and from Thresomin intercept I could land there with 1500 m/s. Instead, with just 650 m/s I got a Graymun intercept, from which I will be able to reach Kerbmun, where I can aerobrake - or take another gravity assist to anywhere. It's Greymun, and not Thresomin, that's the real conveniently placed moon.

Of course, if you are playing a career instead of a single challenge, I can totally see the attractiveness of just landing on Thresomin instead of spending an afternoon doing flybys.

Flyby 4; yet another slight raising of the orbit

Flyby 5; yet another slight raising of the orbit

Flyby 6; yet another slight raising of the orbit

Unlike what I did in other circumstances, this time I'm not trying to come out of a flyby in a resonant orbit. Those orbits are fast enough, an encounter with Graymun is all but guaranteed; instead I just make every flyby as close as possible, to maximize the effect; for that I aim at 15 km. Graymun is mostly flat, but most of its terrain is around 12 km of elevation. After a flyby, I explore future orbits for the next close passage; I always find one within a few days. Then at the next Mesbin apoapsis I make a small prograde or retrograde burn to refine that.

Flyby 7; yet another slight raising of the orbit. This time it took 12 days to find one because Boundless and Graymun have almost the same orbital time

Flyby 8; yet another slight raising of the orbit. Periapsis is now higher than Thresomin

Flyby 9; yet another slight raising of the orbit

Flyby 10; yet another slight raising of the orbit

Flyby 11; yet another slight raising of the orbit

Flyby 12; yet another slight raising of the orbit

Flyby 13; after that I'm high enough to cross Kerbmun's SoI

Encounter with Kerbmun!

Now I'm using the encounter with Kerbmun to eject in a resonant orbit to encounter Kerbmun again. The reason for this is that while I can use aerobraking to reduce my orbital velocity, I also reach Kerbmun with an inclination, and I would like to negate that before I start aerobraking.

Approaching Kerbmun

Aerobraking on Kerbmun

Getting captured by Derbin's gravity and flung away from Mesbin entirely. Ooops!

Derbin is a big moon, it's got a huge SoI reaching down almost to Kerbmun. It's easy to get captured accidentally. Ok, reload and let's try a different trajectory.

New trajectory after first Kerbmun encounter. Stay away from Derbin, and meet again Kerbmun in 35 days

The next Kerbmun encounter; inclination reduced to 2.5 degrees

42 m/s to zero inclination, then it's aerobraking time

I did draw a 60 m/s maneuver at periapsis because, by trial and error, I determined that's the most Boundless can aerobrake in a single passage. That's not enough for capture, and I wanted to see where that would lead - most important, I wanted to check it would not result in crossing Derbin again. Just like I did for Graymun, I'm not worrying about finding the next flyby; Kerbmun has a very large SoI, and those orbits are fast, so a new intercept will be found soon enough.

Closing everything in preparation for aerobraking

The nose cone closing in, seen from the rearward cupola

Aerobraking, at periapsis. Boundless is at the limit of what it can take; a couple km lower, and it would explode. 28 m/s are the speed lost so far

Boundless emerges, opening up again

It took 80 more days, but I got another flyby

Boundless approaches Kerbmun again

Once more, aerobraking to the limit

Once more, by the law of gravity assists, as long as I keep making Kerbmun flybys my intercept speed will remain the same. But if I aerobrake a bit at every passage, my speed relative to Kerbmun will keep decreasing, until I will get captured.

In this second flyby, after slowing 60 m/s in the first, I expect to be 60 m/s slower. But I realize I'm only 10 m/s slower.

I theorize it's because of the sphere of influence approximation. Sure, you leave the SoI at the same speed you came in, but it may be at different distances from the central body. This causes an approximation in how you respond to the gravity of the central body that may cause this irregularity. Just an hypothesis, but I see no other explanation.

Anyway, I didn't even try to predict how that would work. If this effect could randomly accelerate me compared to Kerbmun, it can also slow me down. So I just keep aerobraking until the math works in my favor.

Indeed, at the next flyby Boundless is slower, it only takes 70 m/s to get captured

I don't remember if being slower allowed me to reduce periapsis or if I had to burn for 20 m/s, anyway, I got captured

Kerbmun is well placed to finish the exploration of the Mesbin system. It allows aerocapture, so I could stop there for free coming from Graymun; Traveler also will be able to get captured for free. In an elliptic orbit I can push away for a small cost, and if I time it right I can then get captured by Derbin, using its strong gravity assist to go anywhere. It will be my base of operation while Traveler brings various landers to the rest of the moons of Mesbin.

Edited July 7, 2023 by king of nowhere

[king of nowhere]

Part 2: That's no moon (it technically is, but it's bigger than Eve)

Landers are sent to the outer moons of Mesbin; those include Kerbmun, which is slightly bigger than Kerbin, and Dermun, which is significantly bigger than Eve.

The relative positions of the outer moons of Mesbin. The inset in the lower left corner shows the sub-moons of Derbin. I wonder if there would be some way to make it stable in reality

2.1) That's no Kerbin

Spoiler

With Boundless in stable orbit around Kerbmun, the first thing to do is send Arrowhead to explore the surface.

Arrowhead starting atmospheric reentry

Even through all the flames, you can still see the stars of the Kaywell system. The small red dot is the red dwarf Gememma, with its own subsystem

And a pretty Mesbinrise

What is that strange figure in the sea? I took the coordinates, will want to investigate later

Landed, with no particular problem. 5% oxygen, you could take off your helmet for a while but you wouldn't survive forever unless you were a trained climber

Once landed, I wanted to spend some time exploring the place and gathering science from the various biomes. Arrowhead is a nice plane to fly around, and I want to use this opportunity; many planets in the Kaywell system have an atmosphere, but in most cases it's too thin to fly.

Some science reports are poignant and meaningful. Others are just funny

Nearing some mountains

And passing to the side of a majestic cliff

More mountains on the other side

Unfortunately, Arrowhead has a striking flaw. When I designed it, I wanted a spaceplane capable of propeller flight on Laythe, and capable of ssto on Kerbin, without relying on air-breathing engines, and I wanted a Mk2 crew cabin for various reasons (both practical and aesthetical), and I wanted a cargo bay with all available science instruments, and I wanted the whole plane to be small enough to fit underneath A'Tuin. And as usual, when you have many requirements you have to sacrifice something. In this case, while Arrowhead is capable of propeller flight on Laythe, it is so only by the slightest margin. At high altitude, with less air density, the plane becomes a lot less maneuverable, it's barely able to climb, and it has some serious problems landing. Hence why I passed on the side of the mountain, even though I would have rather swooped over the top. On this planet I can barely surpass 5000 m of elevation; landing is very difficult above 3000 m (meaning I have to save the game first, and go through multiple trial and error), and virtually impossible above 4000.

Going over a stretch of sea, to get a different mountain biome

As I mentioned landing is difficult, here's a failed attempt

To get that last mountain biome I had to land at a lower altitude and then go upwards on the ground. Not really worth it. The terrain was very irregular and I kept breaking the wings.

Finally I'm ready to return to orbit, moving back to the equator first because I don't want to waste deltaV on orbital inclination.

A map of the landed biomes; I forgot a flag on the white biome just south of Arrowhead. All in all I flew quite some distance

But all those landings took a toll on the propellers

Yes, the old propeller misalignment bug struck again. While I've been very careful to avoid moving the propellers in space - by always keeping the rotors deactivated and locked - there is another thing that can trigger the bug: saving and reloading the game with the propellers moving. Which I did a bunch of time to try the landings.

Since this is an issue caused by a bug, I am free to fix it with alt-f12. In this case, I directly brought in a replacement plane.

For the future I vow, if I have to save in midair, I will stop the rotors first. This will complicate flight, but it should avoid damage.

Preparing to go orbital, Arrowhead flies as high as it can on propellers. Which is not as high as I'd like. I should probably add more wings, but they don't fit with the size limit

Then closing the propeller bays and activating the rockets

The oblate Mesbin above me, flames from high speed air drag around me

In orbit with 200 m/s

That's not enough to rendez-vous with Boundless, so Traveler has to go get Arrowhead.

Traveler can aerobrake, but at those orbital speeds it cannot dip much into the atmosphere. Plus it has low drag, even with the cargo bay open. It took a dozen passages to circularize. And when it finally reached Arrowhead...

Traveler rendez-vous with Arrowhead

Dang! Can't dock because the shield of the docking port gets in the way

I had this problem docking Arrowhead and Ice Cream Cone to Boundless, and I solved it during testing. But I completely forgot that I'd have the same issue docking Arrowhead with Traveler. But ok, I have an idea to fix this with EVA construction.

Back to the mothership - which I'll take as an excuse to post this image of the solar panels unfolding

I placed two tiny fuel tanks to act as spacer. Under Ice Cream Cone it's needed, but not under the heavy stage of Traveler, so I can borrow it

However, while taking a spare fuel tank to act as spacer is easy, inserting it underneat the docking port is not. Because when Traveler is detached from Boundless, the docking port becomes the root part. And you can't manipulate the root part in EVA construction.

So I have to change the root part. And to do so, I have to grab a spare docking port (the one that usually holds Arrowhead, since it's temporarily free), attack it somewhere on Traveler, and dock the taxi on that docking port. This will allow me free access to the regular docking port.

I put the docking port on an engine, as it's the most convenient place

Yet another different angle to show the mothership

Traveler is docked by the new docking port. Now I can modify the old one

I place the fuel tank

And now I have to return the docking port from the engine to its original position. But I can't manipulate while it's root part, so I have to turn around Traveler again

Finally I can remove the extra docking port and put it back in its place

Then, after another long sequence of aerobraking, I can finally grab Arrowhead and tow it home

But wait, I totally forgot to investigate that strange anomaly I saw during descent! I also forgot to land on the sea, for that matter. Since I only want to see what's there and take some pictures, I can use alt-f12.

Huh. It seems there are different water textures, and they are not lined up properly

Here going from one to the other

Though it seems like there's a different elevation, it's only a texture

Also, it seems like there's pluricellular life in the water, but not on land. Which is more or less what Earth was like a billion years ago

Finally, I just wanted to show the RCS system on Arrowhead. I didn't want to ruin the spaceplane's profile, but it is very difficult to dock backwards otherwise

Rejoining Boundless

2.2) You can have trojans in ksp

Spoiler

Trojmin is a small moonlet in the L4 lagrangian point of Kerbmun. At 7 km equatorial radius it's bigger than Statmun or Thresomin, but still much smaller than Gilly. Being in a trojan orbit, it's fairly cheap to get there. The main difficulty is not getting accidentally captured by Kerbmun's gravity again.

The trajectory for Troymin. Basically, leave Kerbmun on a smaller orbit until I overtake the moonlet. Less than 500 m/s to get there

I could have used Cigar alone, now that I think about it. Then again, I'm still holding to the fiction that the small landers have food for 30 days or so.

First glimpse of Troymin from a distance

Looking at Derbin through a window. Also visible the submoons Dermun, high above Derbin, and Derminmus, halfway between Dermun and Derbin, barely visible as a few pixels

Arriving at Troymin, with all the major celestial bodies visible in the sky

I am posting a lot of pictures of the sky. Troymin itself is really all not that interesting.

Landing. The surface is heavily cratered

And planting a flag

I didn't explore this celestial body. I already got my share of glorified asteroids, so I immediately returned to Boundless.

The trajectory back. I managed to do it more cheaply than on the outbound trip

And the rendez-vous with Boundless, for the sake of thoroughness. I managed to match periapsis, so it was relatively cheap

2.3) The most challenging landing

Spoiler

Now it's time to tackle the most difficult planet: Derbin. Technically, Derbin is not even a planet, but a moon of Mesbin; however, it's significantly bigger than Eve, it's got 2.17 g of surface gravity, and orbital speed for a low orbit is 5 km/s. Surface atmospheric pressure is 7 atmospheres. It took me a lot of trial and error to build the Phoenix landers for this planet - especially because I didn't want just a lander, but something more elaborate. However, now that I have those tried and true vehicles, I feel safe.

Detaching one of the Phoenix. For the docking part, I regret removing the RCS system in a late redesign

One more unexpected issue here: the Phoenix landers use the normal sized clamp-o-trons, while the rest of my shuttles were redesigned to use the small docking port. I didn't think about it, and now Phoenix can't be attached to Traveler. Fortunately there is an additional docking port where Phoenix was docked, and I could recyle that.

A medium docking port stuck over a small docking port. Not the most elegant solution, but it works

And the trajectory to Derbin. Extremely cheap; Boundless is in an elliptic orbit, a small push is enough to leave, and Oberth effect ensures going to Derbin is easy. Oberth effect also means cheap capture

Meanwhile, I decide to also make use of a Redentor probe.

I took a bunch of nice pictures with the Redentor,  but I'm probably already going over 100 images for this chapter alone, I have to cut somewhere. I mean, I took over 1300 screenshots for this mission, I can't post them all.

The docking of Traveler and Phoenix is not perfectly aligned with the center of mass. I compensate by shutting down an engine

Getting closer to Derbin, here a spectacular double passage of Dermun and Derminmus

Here the two submoons are well visible as Phoenix approaches Derbin; At least Dermun is well visible, Derminmus is darker and harder to make out

For capture I use a rocket burn; Traveler is moderately reinforced for aerobraking, but nowhere near sturdy enough to survive an atmosphere at 7 km/s. Even Phoenix can only take a shallow passage at that speed. So I get captured in elliptic orbit, then at apoapsis release Phoenix to aerobrake.

Phoenix is released

Jettisoning its docking port, Phoenix has a small engine and a bit of fuel. Just enough for deorbiting maneuvers

The thermal shields are deployed. Here one is completely covering the cupola. It will glow red in the atmosphere

First aerobraking. The atmosphere of Derbin starts at 58 km, this is a shallow passage. I determined that at 49 km Phoenix explodes

Coming back, Phoenix passes very close to Derminmus

A view from the crew pod. You can see the thermal shield is glowing, so we're in the atmosphere. Those clouds completely cover the view. Also, this pic is in natural light; amplification makes the clouds glow

And here Phoenix passed close to Dermun; it still skipped its SoI, else a course correction would have been required

Just a funny science report

It took a bunch of aerobraking passages to go from elliptic orbit to circular orbit, Phoenix had to lose 2 km/s. But eventually it was ready to take the deeper plunge.

Phoenix is almost overheating during descent. I'd be very nervous, but I already tested this vehicle and know it will work

Deceleration reaches 10 g, Phoenix is losing speed fast in the middle atmosphere

Descent completed, we finally see the surface. Now I only have to landing

Oooops!

Something went wrong with staging here...

Almost made it. The crew survived, at least

Phoenix is quickly falling, and I have to remove all the layers that protected it from the high speed reentry, without the discarded thermal shields hitting the plane. Not very easy, considering that they are discarded both from the front and from the back. And then I have to land. To complicate matters, I arrived on one of the high areas of the planet, the ground here is at 10 km of altitude; Phoenix flies easily and is easy to control at lower altitudes, but here the minimum speed necessary to keep flying is dangerously close to the speed at which the landing gear will be destroied, no matter how soft the landing.

And sure, I already tested this vehicle and made it work. But that was months ago; there was a complex sequence involved, and I don't remember it.

So I had to discover it, by trial and error. A very frustrating process, the thing that kept me going was the certainty that I made it work once and therefore it had to be possible.

It turns out, the propellers are the key. Specifically, the first problem is removing the front thermal shield without it hitting the plane. For that, I have to activate the propellers and angle them to increase drag. The propellers are not enough to stop Phoenix midair, but they can greatly slow down the fall. Once released, the thermal shield will fall at roughly 40 m/s; if Phoenix is falling slower, it will be able to release the shield without being hit by its own debris.

Discarding the front thermal shield

Discarding the other thermal shields

At this point Phoenix must accelerate, because the other thermal shields are discarded from the back and they must go slower than the plane, else they hit it. But not too fast, else the lateral shields can destroy an elevon. First the central shield is removed, then the other two. Notice how the fairings that protected the propellers were discarded first, but they are still stuck in their place; that seems a bug, eventually they drop.

Achieving level flight

Then the next challenge is achieving level flight. As you can see, by the time I drop all the shields Phoenix is less than 2 km from the surface, and falling point first. At a high altitude where the atmosphere is less cooperative. So I have to accelerate Phoenix and try to achieve level flight before hitting the ground.

And all this must be achieved in a single sequence, without reloading, else it will damage the propeller.

At this point I can pick up some altitude, stop the propellers, and save before attempting to land. At this altitude, I need to land at 80 m/s. Risk of damage to the landing gear is high, but it is feasible.

The only thing I don't understand is how I could devise that complicated sequence the first time, without any knowledge of whether Phoenix would work, if I had so much troubles finding it later.

Finally landed!

Just the atmospheric analysis

This picture shows EVA experiments, but it also shows how kerbals are supposed to return inside Phoenix; the ladder on that laboratory is low enough for grabbing. Also, Gememma shines nicely

Finally, an image from the backward cupola. I included it for something

You may notice that the cupola is turned upside down, and I turned around the image to have the ground on the bottom. As I made Phoenix many months ago, I have no idea if I intentionally made the cupola this way to have a better view of the ground, or if it was a design mistake. However, putting the bulky control panel on top does give a better view of the ground, and the picture does look good when rotated 180°.

2.4) That's no monument valley (but a pretty good shot nonetheless)

Spoiler

Derbin is geologically unique. It has continents and mountains very similar to those of Earth - something rare in this game, where most mountains are just random lumps of elevated terrain. It also has a clear distinction between continental crust and oceanic crust. I really miss not being able to see the shape of the continents from up high, the clouds cover everything from above. I suppose the mod creator wanted to keep the terrain a mystery - a supposition corroborated by him defining the information that Imterril is a water planet "a spoiler". What can I say, it's completely unthinkable for me to launch a mission to a planet without knowing exactly what's there and without having tested the lander to make sure it works in those conditions, but I suppose there could be people who will launch a probe to that mystery cloudy planet without knowing what's underneath.

Anyway, despite being apparently a lifeless desert (I wonder what happened to the water, there's a lot of it in the atmosphere and the planet has enough gravity to avoid losing it) Derbin has some spectacular views and I spent several hours flying Phoenix around. I took hundreds of pictures in the process, here showing only the most significant.

The ground seen from the crew pod in flight. I made sure Phoenix would have multiple good spots for IVA views

View from the cupola, with Mesbin and Kerbmun in the sky

Derminmus is passing in front of Dermun. How is it that from the surface you can see space so clearly, but from space you don't see anything of the surface?

With some magnification you can also see Graymun

I mentioned continents; here's a continental shelf

We could see such shelves on our planet too, if we dried up the oceans. Well, the cliffs would not be so dramatic, but the continents are indeed raised platforms. This feature is not found on any other ksp world, and makes me curious. Unfortunately I cannot see the shapes of such shelves - or the presence of other major mountain chains - because the clouds prevent seeing the terrain when I zoom out.

Flying over the continental boundary

Seen from the pod

Seen from the cupola, looking backwards

The cliff marked a biome boundary, so I landed there, run some science, and returned back to aim for new biomes. In the lowlands flying, and especially landing, is much more easy; Phoenix can sustain flight at 50 m/s, making for a trivial landing.

Going back up the continental ridge

Flying past a curious rock pinnacle

Gememma and Dermun

A mesa, seen looking down from the pod

This high elevation rock amphiteater has two new biomes on top

Unfortunately, while Phoenix can barely fly up to that altitude, it definitely cannot land in those conditions - not that this prevented me from bashing my head against the wall of futile attempts. Since I wanted to get science from those biomes, I landed Phoenix and went up on the ground.

Phoenix used as rover; or perhaps just landed, seems too fast to be driving on the ground

Phoenix used as a rover. It will manage to climb up the cliffs

And here flying again towards the equator, in preparation for ascent

The milestones reached. Considering the size of the planet, that's probably 1000 km of flight

I left Phoenix parked on the ground. I gave it some large living room to simulate a mobile base that could stay on a planet for months.

2.5) Dermun and Derminmus

Spoiler

While Phoenix completed its ground exploration, Traveler is still waiting in high orbit. I realized, since Phoenix is completely discarded on ascent, that I could return to grab Cigar, and land on the submoons of Derbin, before going back with the whole crew.

Traveler returns to Boundless

Unless I can match periapsis, those rendez-vous around Kerbmun are uncomfortably expensive. They negate the other advantages of parking there

Traveler grabs Cigar

And the trip back to Derbin

With the trajectory for Dermun

Getting captured in low Derbin orbit makes for an extremely cheap capture, but then it's 200 m/s to lower apoapsis to Dermun and 500 m/s for capture. I wonder if it's better. to enter Derbin orbit level with Dermun; it will make for a more expensive capture, but intercept on Dermun will be much cheaper

Indeed, 100 m/s for Derbin capture but only 200 m/s for Dermun capture, and no need to lower Derbin apoapsis. Much better

Approaching Dermun. It doesn't really look like Mun; it's much less cratered

Commencing landing operations

Landed on Dermun

I spotted a mountain in the distance and I decided to climb it with the rover

It was a hard climb; this mountain has steep cliffs all around, and Cigar has a high center of mass. This prevents switchbacking, as the rover would roll laterally

Actually, it would be possible to switchback if I could detach the attitude controls with the wheel controls. This way I could keep applying a roll to the rover to counteract gravity, while pushing forward with the wheels. But I drive by turning the reaction wheels off when I use the regular wheels, a method that's easier to learn and practice, but not as efficient in a difficult spot like this one. The tiny light in front of Cigar pointing back at the crew cabin lights up when reaction wheels are off; I discovered that having a visual indicator of that is comfortable.

Despite the difficulties, Cigar made it to the top

A better view of the mountain. It's surprisingly low, but hard to climb nonetheless

Away, to Derminmus. I forgot to take pictues of the maneuvers involved, but total cost was probably around 400 m/s, mostly for Derminmus capture

Derminmus! It's not green like Minmus, except in some patches. Probably more realistic. Those could be salts pans left behind by quick water evaporation, colored green by copper carbonate

Derminmus is very flat, to the point Cigar could accelerate to high speed despite the low gravity. In that it resembles Minmus. I also wanted to show the fuel level on Cigar

I went to plant a flag on a salt pan before leaving. In this low gravity I don't even have to find a slope, using reaction wheels to point up is enough

Rejoined in orbit. 4500 m/s left on Traveler may seem like a lot of fuel, but it's actually pretty short for what it has to do next

I'm referring to the fact that now Traveler will have to pay 2 km/s to lower orbit around Derbin to a low circular orbit to grab the crew of the Phoenix. And then it will need 2 more km/s to leave Derbin. Not much deltaV to spare.

To lower Derbin periapsis, I'd need 800 m/s

Going outward, and using a gravity assist from Dermun, saves a little bit of fuel

The above trajectory is such: first 200 m/s from Derminmus to Dermun. At Dermun periapsis, 300 m/s to lower Derbin periapsis - in addition to a gravity assist from Dermun and Oberth effect, it's enough to reach the desired low periapsis. But the earlier trajectory would result in an apoapsis at the level of Derminmus, while the current trajectory would place apoapsis at Dermun; so to properly simulate which is cheaper I also need to include an additional cost to reduce apoapsis to Derminmus. Which is what the third maneuver (217 m/s) is. All in all, this stunt saved 50 m/s, it was probably not worth the effort.

Traveler approaches Derbin periapsis. Visible in the sky Mesbin, Dermin, Derminmus, and what could possibly be Graymun by magnification

I experimented with aerobraking, but Traveler is not sturdy enough. It can lose at most 1 m/s without exploding. Faced with the prospect of doing 1600 consecutive aerobraking passages, I decided to use the rockets. In retrospect, I should have loaded more fuel when leaving Boundless. But right now it's faster to salvage the mission as it is than to reload all the way back.

2.6) The most challenging ascent

Spoiler

Now it's again a difficult time: getting Phoenix back to orbit. At least in this case the sequence is easier to figure out, there's only one way staging can be performed. Not that it's going to be trivial. Especially because I did not follow exactly the safety procedures for propellers, and they ended up taking some damage.

As you can see, the rotors are bent out of place, probably by aerodinamic stresses. Autostrutting the rotors reduces the problem

For Arrowhead I got a replacement, but Phoenix is single use, so I decide I'll try to fly it anyway.

First step, transfer the crew to the front seats

Once over the fairing, they can jump on the external seats

Phoenix takes its last flight

Dropping the front wheel. Now there's no turning back

Dropping the habitat

The plan assumes to drop the habitat for reduced weight and keep climbing on propellers and battery power. But with the propellers bent out of shape as they are, Phoenix is unstable once it drops the habitat section. So I have to skip that part and hope I'm high enough. I managed to reach around 13 km of altitude before flying became too unstable.

Dropping also the wings, Phoenix ascends on a vector engine

This part of the flight is made difficult by the need to pull up the nose. Phoenix must not accelerate too much in the lower atmosphere, else it loses too much to drag. But pulling up the tip too much causes the rocket to become unstable.

Dropping the lateral boosters. No idea what exploded, but Phoenix is undamaged

Finally dropping the first stage, the next part of the ascent stage is a wedge powered by a dart engine

The first set of drop tank, comprising the tip, has run out and is discarded. Also the fairing, drag is negligible at this point

Phoenix, now much lighter, keeps climbing up on the dart. It must reach a relatively high apoapsis, because the next stage has low thrust

Dropping the last droppable tank, and also the dart engine. A smaller spark engine will propel what's left of Phoenix for circularization

The spark has low thrust, but there's enough time to apoapsis to make full use of the fuel on board

Orbit acheived, with 100 m/s left

After some maneuvering on both ships, Phoenix reaches Traveler

A treasure trove of science data is transfered. Yes, it's not relevant to the mission, but I'm still going out of my way to get as many experiments done as possible

The now discarded Phoenix is last seen floating in front of Traveler. Also, a comet

Now, to leave Derbin I need almost 2 km/s. Traveler barely has that much, though it won't leave enough for rendez-vous with Boundless

I could save a bit by gravity assists from Dermun, but I decided not to. It takes over 1600 m/s to raise apoapsis to Dermun, by that time there's very little to gain. I don't want a repeat of the long sequence I did on Graymun when it would only save a ton of fuel.

Arriving on Kerbmun. By the wrong side, and with barely any fuel left

Aerobraking

The intercept speed was low enough that Traveler didn't even need rockets to get captured. It did need a bit to raise periapsis and enter a stable orbit.

Traveler in a stable orbit, with less than 50 m/s left

Now I need a rescue mission to grab the taxi. It takes almost 1 km/s to go from Boundless to Traveler, and then there's also the return trip. Unless I move the whole mothership, but of course it's too expensive if I have better options. Ice Cream Cone is made to carry liquid fuel but it only has chemical engines (in retrospect, I would swap two wolfhounds for two nervs), so it's unsuitable for a high deltaV mission. Arrowhead may be able to make it, but it's relatively small, I don't know if it would have enough deltaV with the added mass of Traveler.

However, Traveler has a heavy stage, which I haven't used so far, that's practically a glorified fuel tank with nuclear engines. It's perfect for the job. It lacks a probe core or antennas or power generation, but a Redentor probe can dock with it and form a new spacecraft. I keep being surprised by how often it turn out useful to have a small probe around.

The traveler heavy stage docked with a Redentor, ready to reach Traveler

And here they are, having completed the docking. There's no place for Redentor to dock here, but it's got enough fuel to return on its own

The maneuver required to go from Boundless to Traveler orbit

Raising periapsis in a circular orbit is about as expensive as circularizing in low orbit by aerobraking and then raising apoapsis, but aerobraking with those ships requires multiple passages, so we'll stay in high orbit.

This completes the innumerable moons of Mesbin. Boundless is ready for its next destination: the superearth Valyr, where it will drop the remaining Phoenix lander, so it will travel more lightly in the future.

Wow. This was a very long chapter. If I had realized it, I would have split the exploration of the Mesbin system in three chapters instead of two.

Edited November 16 by king of nowhere

[king of nowhere]

Part 3: If Laythe was 12 times more massive, it would be Valyr

Boundless sets to explore the Valyr system, and refuels on Oshan.

The position of Valyr in the Kaywell system, and the moons of Valyr. Not shown is Didd, the diminutive submoon of Manonam

3.1) No gravity assist needed

Spoiler

I choose the parking orbit around Kerbmun because it was very convenient to launch for interplanetary. Indeed, it turns out there's not even need for a gravity assist from Derbin.

Trajectory to Valyr

160 m/s to leave Kerbmun, coupled with Oberth effect from the big moon and from Mesbin, and adding the rotation of the moon itself, are enough to raise apoapsis to Valyr. I won't be meeting Valyr immediately, though; the downside of launching from an elliptic orbit is that you cannot choose the time of launch, so you often have to launch outside of an optimal transfer window and make multiple orbits to meet your target. The red maneuver is for that. Afterwards, it takes 9 years to reach Valyr; I said Boundless would have 50 years worth of life support, so it's fine.

Last view of Kerbmun before departing

Arrival at Valyr with aerocapture on Oshan, the major moon

Valyr is a superearth-type planet, or superkerbin, or however you want to call them. It's very close in size to Derbin, and my main reason for going there first is that I can drop the second Phoenix and have a symmetrical mothership again (for this trip, I managed the asymmetry by shutting down a few engines). Though it's also, surprisingly, a good position to go to the inner planets, which will be my next target. But I'm putting the cart in front of the horse; first Valyr.

Valyr has a smattering of small moons, and one major moon, Oshan, which is suspiciously similar to Duna. It's one of the places where I'm allowed to refuel by my own rules, and the atmosphere, gravity and position make it a perfect place to park Boundless while I explore the Valyr system.

Approaching Valyr and Oshan

Oshan terrain is a mixture of Duna and Eeloo

Aerobraking

The low gravity and low intercept speed made this a very simple aerobraking. I probably wouldn't even need to bother closing the cargo bays. The only unexpected issue is that, despite Oshan atmosphere reaching up to 94 km, it is extremely thin even at lower altitudes. I had to go down as low as 30 km before I could get some significant braking.

3.2) The last flight of the Phoenix

Spoiler

First item of business is dropping the Phoenix. While lag is nowhere near comparable to what I had to deal with in my kerbalism grand tours, Boundless still slows the game noticeably. While I will miss Phoenix and the unique exploration opportunities they give, I am looking forward to reducing part count by another hundred.

It's surprisingly cheap to get inside Valyr's atmosphere from Oshan. On Derminmus it took 800 m/s to get in the same place. Thanks to Oberth effect and higher orbit

Phoenix commences aerobraking

Valyr is very similar to Derbin, but it has a major difference; it spins very fast. Not as fast as Mesbin, but the surface is moving at 600 m/s, so achieving orbit is much cheaper compared to Derbin. It also means that what is reported as surface speed in the screenshot above is actually 6600 m/s of orbital speed.

A beautiful sunset over Valyr

Flying over an archipelago

Valyr is an ocean world scattered with islands, much like Laythe. It's also significantly warmer than its distance from its star would suggest, also similarly to Laythe. Though in this case the heating is from greenhouse effect, while on Laythe gravitational heating is responsible.

Landing is a lot easier on Valyr, because while it has 20% less atmospheric pressure, it also has many less plateaus. On Derbin I had to land over a continental mass that was, on average, 9 km above the datum level. On Valyr I can land over the sea, where flying is a lot easier.

Dropping the first heat shield. I won't repeat the full sequence

And trying to reach the closest island before the battery runs out

While Valyr is easier than Derbin in many aspects, one significant disadvantage it has is its fast rotation and distance from the sun. Because Phoenix is solar powered; it can barely sustain flight with the sun overhead, and with the fast rotation it means it only has an hour or so of optimal conditions where it can sustain fligh. Otherwise it's limited by battery power.

I didn't have enough battery to land on the island, so I was forced to splash-land

Envisioning such a scenario, I made sure that Phoenix was fully capable of splash landing, no issue here.

Underwater view. Looks pretty nice

Looks like there's life in the water of Valyr too

It's also possible to play golf underwater

The problem with splash landing is that Phoenix cannot take off from the sea; that requires way more power than it has. So I will have to slowly reach the island at low speed before I can take off again

The moment when the wheel touches land is potentially dangerous; in this gravity breaking a wheel is easy

Planting a flag, and atmospheric composition

I definitely like Valyr. I'll be staying and exploring a while before returning to orbit.

Flying towards the sunset

Some of you may remember what I said about flying on Valyr and electricity. So I found myself stuck mid-air with no land in sight. I had a few options:

1) Reload, and pick a better time to leave

2) Splash land, and prepare for a very long trip at snail speed the next day towards the nearest land

3) Cheat infinite electricity

Both 1 and 2 would entail losing a lot of time, while 3 wouldn't have any practical effect on the grand tour itself, so I picked it.

Here I look closer and finally discover that Phoenix was asymmetrical all along

Damnit. I wanted to make a symmetrical vehicle, but in the spaceplane hangar I clicked the lateral boosters just slightly offset, and didn't realize it. So all this time the propellers were misaligned with the center of mass, and the first stage of the rocket was also misaligned. No wonder I had problems making it fly straight. It's a minor miracle I brought its twin to orbit in the first place.

Since the other Phoenix managed to perform well on Derbin despite this flaw, I decide to not try to fix it.

My target was a bigger island where I may find more biomes and more variety.

Indeed, there's a fairly large mountain

Just some nice flying around

I accidentally dropped Val out of the plane. Fortunately I was able to land her and Phoenix safely without going out of physical range

How do one "accidentally" drop a kerbal out of a plane? I have to explain how I've been taking EVA reports while in flight. Which itself begs the question of why I'm trying to take EVA reports while flying when it's clearly dangerous and there are no benefits, but humor me, I like taking science reports.

At the speed and atmospheric density of Phoenix flight, a kerbal cannot hang on the ladder, it gets pushed by the wind. However, Phoenix has a long crew section with an unbroken ladder on top. I theorized that if I send Val out from the crew pod - the first in the line - then wind would push her back over the hitchhicker container and the lab, and once on the lab I could press B and get her inside again. And in the meanwhile I would have a few precious seconds to get the crew report. Indeed, it works. I've been collecting reports this way on Derbin too.

What went wrong here is that I forgot to move Val from the lab back to the crew pod after the previous time I sent her out. So she went out on the back of the plane, and she had no more chances to get back in. Fortunately, I also forgot to remove the parachutes from the crew equipment when I started the flight (I mean, what would you need a parachute for in a grand tour? Unless you accidentally dropped one of your crewmembers out of your lander in midair on one of the few planes where parachutes work, that is). So I was able to recover from this mistake. Good thing, because I hadn't saved in a while.

Landing on top of a 6000 m mountain

Actually, Valyr atmosphere being significantly thinner than Derbin, 6000 m is already higher than where I can land. I landed at a lower elevation, and went up as a rover.

And a final shoot from the cupola

A map of the explored region

I've covered quite some ground. While Valyr is really pretty, it's also very big, and I'm not interested enough to go on some of the islands on the polar regions.

Now, before going to orbit, I must make sure Traveler is in place. I'm still pretending kerbals cannot live long with just a spacesuit, meaning I can't send them to orbit and leave them there waiting.

While lowering orbit, Traveler came close to the minor moon Denna

Phoenix takes off for its last flight. Here it drops the front wheel, crossing the point of no return

This time I was careful to protect the propellers, so Phoenix can work as intended, drop the habitat section and gain a few more km of elevation

Here pressure is 0.5 atmospheres. Phoenix could keep climbing, but it's losing speed; it's more efficient to start the rocket now

Rocket ascent started. Thankfully the vector engine has a large gimbaling, so it can compensate for all the aerodinamic and center of mass issues

Second stage, keeps on climbing

And third stage

Here I had another unplanned issue: this stage veered to the side. It's not normal, I checked; this final part of Phoenix is perfectly symmetrical. However, for unknown reasons, this one acted like it wasn't, and pulled on a side. I had to reduce thrust to the level where the reaction wheel could compensate. Which was a significant problem when trying to leave a planet with 2.17 gees of gravity, but after some trial and error Phoenix made it.

Dropping the nose. I'm pointing above prograde to compensate for low thrust

Finally, the last stage. I managed to raise apoapsis enough that it could finish circularizing

For a moment, I thought I spotted the asymmetry in that seismometer attached to the side, but I just checked, it wasn't enough to cause any issue. I also checked that fuel was being drained by the round tanks evenly. So, whatever happened to imbalance Phoenix was likely a bug.

Still, Phoenix made it. It completed its last flight despite the game trying to kill it. It was a very nice vehicle for a very difficult task. I will miss flying Phoenix over some giant world, sending out Val to take crew reports. If I ever need something similar again, I may end up recycling the design.

3.3) Small moons

Spoiler

The reason I took that seismometer from Phoenix and saved it is that I realized the two innermost moons of Valyr are very tiny. Instead of returning to Boundless and fetching Cigar to land, I may as well land with Traveler directly. Traveler has a full science suite, except for a seismometer, because it wasn't supposed to ever land anywhere. But the Kaywell system is full of those tiny rocks. No point carrying around Cigar needlessly, and especially no point making an extra trip.

Trajectory for Denna. 850 m/s to raise apoapsis to intercept, because Phoenix still had some deltaV left and I didn't need to fully circularize Traveler

And 900 m/s to capture, split in two burns, because a moon this small has no Oberth effect

Denna looks like a green potato

A green potato with craters

I have many pictures of Valyr from up close or from afar, but none from a middling distance. I compensate with this view of the planet from the surface of Denna

A very poignant science report

Denna to Plaph. Less than 400 m/s, because the gravity of Valyr is weak at this distance

Plaph looks like a giant rock. Or maybe just a differently shaped potato

Landed on Plaph

Plaph to Oshan. 400 m/s, then aerocapture

As Traveler has almost 3 km/s left, there's not much point showing the return to Boundless. I'm trying to make those reports shorter, and I already posted enough pics of my mothership.

3.4) Manonam and Didd

Spoiler

Next target is Manonam, roughly the size of Ike, with its submoon Didd. For this I need Cigar.

Traveler picks up Cigar

Only 11 m/s to eject to Manonam, and 17 m/s for a plane change

We are far enough from Valyr that moving between orbits is practically free. So for this section I'll stop posting the trajectories, the whole trip costed less than 1000 m/s.

Arriving at Manonam, I go first for Didd. The main difficulty is finding it.

1.8 km of closer distance, and still I'm not inside its sphere of influence! Didd is truly the tiniest object

Indeed, with a nominal radius of 0 km, a SoI of 1.5 km, and less than 2 m/s escape velocity, Didd is barely bigger than randomly spawned asteroids

First look at Didd, on the right of the image. The black ball covering the "milky way"

Didd is completely black, even though I am using 100% light amplification here. Turns out it's a bug; Didd itself is nowhere near that dark, once you get inside the sphere of influence.

It's kinda ugly

A very significant science report

Didd feels kinda pointless. I could have circumnavigated it since I was there, it would have taken maybe half an hour. No, wait, I could have maybe achieved escape velocity with wheels alone. Whatever. Those tiny rocks are getting repetitive. Without further delays, I go to Manonam.

Cigar prepared to land on Manonam

Look in the distance, I found an arc!

I wasn't going to drive here. This world is dull, and it only has two biomes (one equatorial, one polar). But since I have an arc in my sight, I may as well go there.

I got this chance to showcase the light informing me that reaction wheels are off. I introduced it on Dancing Porcupine 2, here I improved the design by making it visible in IVA view

The arc looks quite impressive from within the rover

I made a point to fly inside the arc to return to orbit

Back to Boundless, now reduced to 793 parts. And it will stay 793 parts until the end

3.5) Oshan to explore and Oshan to drill

Spoiler

Finally I have to explore Oshan with Arrowhead before refueling.

If I just wanted to plant a flag, I could just send down Ice Cream Cone. But Arrowhead has the full science suite, and it has the capacity to move on the ground.

Of course, Arrowhead cannot fly on Oshan. The atmosphere is too thin. It will land with rockets, assisted by a parachute that I'll lend from Ice Cream Cone.

Taking a parachute from Ice Cream Cone to strap on Arrowhead

Arrowhead, descending on Oshan, with a parachute strapped on top

The parachute helps to keep the plane pointed with the engine towards the ground

It's an uncomfortable landing, but feasible

A bunch of interesting science reports from the surface

I have to say, there's too much life around here. On Kerbmun, life. On Valyr, life. On Oshan, life too. Multicellular life. Seems a bit too much.

Oshan, like Derbin, has continents and seas; in this case the seas are ice plains, almost perfectly flat, criscrossed by cracks. I landed just in the middle of the bigger sea, too far from a continent to want to go there. But I'm close enough to a crack to go scouting.

Driving Arrowhead on the ice plains

There's not enough air to fly, and the propellers have low power, but there's nothing to stop Arrowhead from building up speed.

The cracks. Was it worth going this far to see them? Probably not

Back to Boundless, the RCS already in place for docking

Now it's time to refuel. I'll finally see how well Ice Cream Cone performs.

Detaching. Of course, I put the parachute back in place

I gave Ice Cream Cone a strong RCS system because I'll have to perform a lot of docking, may as well make them comfortable.

I also put a cupola on its back, because it was cool

Here in the final part of the descent, opening the parachutes

I made Ice Cream Cone in its shape because I wanted it to have a pointy part, to minimize drag during ascent, but I also wanted a flat back, to maximize drag during descent. As far as I know, a flat back doesn't make too much of an impact on drag at high speed, so it will help descent and be of minimal problem on ascent. The only problem is that Ice Cream Cone may get turned around by aerodinamic forces, in this case it will be too fast to open the parachutes and it will crash on the ground. Here it's not a problem, in the worst case I'd have to provide some rocket braking to stay below the point where aerodinamic forces can turn the lander around.

Terminal velocity on parachutes is 60 m/s, need to use the rockets a bit

Though Ice Cream Cone has high thrust (1.3 fully loaded), so it can activate the rockets at less than 100 meters from the ground. That's actually overkill; it's supposed to be able to take off from Lito, but let's face it, I'll never go there. Lito is as big as Tylo, and the atmosphere is thin enough that I would need rockets to slow descent before opening the parachutes. I wouldn't be able to carry much useful cargo. And orbiting the same gas giant is Totooa, which is a much better refueling spot. So, I could have gone for less thrust and saved some mass.

In fact, thinking back, I'm not happy of Ice Cream Cone propulsion. Eight wolfhounds are overkill for a Duna-like planet. At the same time, they are whoefully inadequate where there is a thicker atmosphere. And wasteful if I have to reach a ship in elliptic orbit. If I could go back to the drawing board, I would give Ice Cream Cone maybe 2 skipper engines, 2 wolfhounds, 2 nervs. Or something like that.

As it is, Ice Cream Cone will not work on Egad, except maybe if there is some high plateau. It will probably work on Totooa, but only because the planet is fairly small and the wolfhounds will be enough to lift the ship even with a fourth of their optimal thrust; in any case, it will be very wasteful. It will not work on Gannovar. There, with one design mistake I halved my already small selection of refueling places. Then again, Oshan and Ollym alone would already be enough; it's not a critical issue.

Ice Cream Cone has a solar array to maximize the sunlight received. Except when the sun is straight overhead

View from the crew cabin. I wish I had used only 6 engines and left a better view

It also has a ladder to go and plant a flag. Not really needed, jumping works

Ice Cream Cone fuel tanks hold 125 tons of liquid fuel, 38 tons of oxidizer, and 1.5 tons of ore. It takes a couple days to fill them.

Something went wrong with this takeoff, some engines remained on the ground...

Ascent, at a low angle

I run some experiments, and determined that a low angle works better. Though it takes several minutes to clear the atmosphere, drag losses are still lower than gravity losses.

View from the rearward cupola during ascent

Unfortunately I cannot use the rearward view more often during ascent, because whenever I do the ship believes that back is front and tries to flip around. Even with SAS deactivated.

And a view of Oshan with the thin atmosphere emphasized

As I left Boundless parked in elliptic orbit, Ice Cream Cone still has some deltaV to spend - though I lowered the mothership a bit to make things more comfortable. Here's where a couple nuclear engines would come in handy. Also, I am unhappy with the fuel tanks. I spend all the oxidizer going up, and use the ore left to make more oxidizer, and this way I barely reach Boundless. It's good because I'm only refilling on liquid fuel. But if I wanted to carry up oxidizer, I would only be able to carry a small amount. I wish I had used less fuel tanks and more ore tanks, so that I could choose to make oxidizer or liquid fuel.

This spacewalk is to pack the parachutes. They are too high on the body of the rocket to pack them while it's landed

And finally, I wish I had put the crew cabin in the middle of the rocket, where I could send out an engineer and pack the parachutes without needing to spacewalk. Having to fly around every time is annoying.

At every mission, Ice Cream Cone could bring up 95 tons of liquid fuel. With eleven refueling missions, it topped the fuel tanks of Boundless.

Status of Boundless after the refueling

This also marked the moment where I started writing this report; this refueling confirmed that everything works well enough.

So far I could get away with relatively cheap transfers, but this time I filled the tanks completely because the next target is a lot more expensive. I'm going for the inner planets.

Edited July 14, 2023 by king of nowhere

[king of nowhere]

Part 4: A sky full of two stars

Boundless plunges into the very inner system. Plunges as close as possible to Kaywell and Limnel without burning up, comes close to Shol and lands on Wolda. Finally it leaves for Tannor, moon of Tyepolbynar, for refueling.

The structure of the inner Kaywell system. Notice the very close distances from the sun, and compare the orbit of Tyepolbynar here and in chapter 3

4.1) Inward!

Spoiler

Before venturing outwards, I prefer to finish the inner Kaywell system. Besides the gas giant Tyepolbynar, in an orbit comparable to that of Eve, the Kaywell system features a couple of celestial bodies extremely close to the binary stars; the giant planet Shol, and the glorified asteroid 2-Wolda. A grand tour requires me to only land on Wolda, but I would like to achieve some more. What's the point of a whole gas giant if you never visit? So I will try, if possible, to:

- make a flyby of Shol

- make an atmospheric dip on Shol

- enter low solar space

- make a flyby of Limnel

- pass between the stars

Objective "land on a comet" instead has to be canceled for the dumbest reason: tracking a comet requires an infrared telescope, and Boundless was supposed to have two, but they were removed during one of the countless refurbishing all my motherships go through during the testing phase, and I never put them back.

But first things first. Traveling inward requires a lot of deltaV. A lot more than for Moho, because my targets are a lot closer to the sun. Fortunately, there are several giant planets that I can use for gravity assists.

From Oshan to Mesbin; I'm not in an ideal launch window, but Boundless elliptic orbit forces to launch at this time and meet Mesbin at a later orbit. Ejection from Oshan is cheap

The plan is thus: from Oshan and Valyr, get a Mesbin intercept. Notice how I'm not going in a Hohmann trajectory; I want to have a high intercept speed, because I must leave with a low solar apoapsis, and that requires a high intercept speed on Mesbin. From Mesbin get an intercept on Tyepolbynar, once again not Hohmann because I need a high speed. From there, go all the way down to Shol. From Shol I can take another assist to go down to Limnel, or - if that proves unfeasible - I can enter into an orbit that minimizes intercept speed on Wolda. I still expect to need lots of km/s for Wolda, but Boundless is well stocked.

Mesbin will put Boundless in the red orbit, which will cross Tyepolbynar

A plane change while a comet zips in the inner system

Mesbin flyby, fairly close because I need a big trajectory change. If Mesbin wasn't so massive I'd have to eject into a resonant orbit and take multiple assists

The planned Tyepolbynar flyby. I need an additional 800 m/s to reach Shol

My intercept wasn't fast enough, and I needed to boost it with 800 m/s from a periapsis burn.

It wasn't very efficient. If I started from Oshan with a lower solar periapsis, I could have gotten a faster Mesbin intercept and save fuel here. However, Boundless has a lot of deltaV, and I'm not concerned with running out; I'd rather not repeat a few hours of game just to save a trip of Ice Cream Cone next time I refuel. This is still a decently efficient way to reach Shol, as most of the cost is paid by the gravity assist and the other is greatly mitigated by Tyepolbynar gigantic Oberth effect; this gas giant is a lot bigger than Jool.

I will also need to pay for a plane change, I can't afford to not be equatorial when reaching Shol. Only 0.5 degrees, but this close to the sun it will still cost a few hundred m/s.

The burn at Tyepolbynar periapsis, with a couple of science reports I found particularly interesting

First good sight of Shol, glowing red hot left of Kaywell. It's not much smaller than Limnel itself

Boundless is starting to overheat well before reaching Shol

I hope the 10 giant radiators I installed specifically for this part of the trip will be enough. I did not think to check specifically for thermal resistance close to the sun.

4.2) To Limnel and/or Wolda

Spoiler

One of my optional objectives was a Limnel flyby. Let's see if it's possible.

It's not clear from the picture, but I don't have a periapsis

It seems that, no matter how I try to enter, I get pulled too close to the star by its gravity. Sure, I could make a maneuver to raise periapsis, but this close to a star's gravity well the maneuver would be way too expensive. Especially because I still don't know how close I can go before burning. Let's start by determining that.

A spectacular view of a close comet

This is roughly at the level of Shol orbit, and Boundless is having some serious overheating issues

Ok, time to put the ship in aerobraking configuration. Except that I'll leave the radiators open, of course. This will add a lot of thermal resistance to the mothership.

Approaching Shol. Still with a comet

Near Shol. Shol is significantly bigger than Tyepolbynar, which is itself much bigger than Jool. It takes a true giant to avoid losing atmosphere to the solar wind this close to Kaywell

Now Boundless can take the heat like a champion; see the radiators are glowing red hot with waste heat, but the ship is cool. Somewhat. At 1 million km from the sun. How closer can it go?

Boundless about to explode at 680000 km. The overheating level for the crew pods is almost full. Look at how big is Kaywell

So, I have my answer. Boundless can go roughly 650 thousand kilometers from the star surface, then it melts.

Limnel orbits at 300k km, so there's no chance of getting close, even if I could find a good trajectory. Passing between the two stars is not even worth considering. At least I could go to low solar space, that starts at 1 million km; some nice science reports are included in the Shol flyby picture.

If I could go back to the drawing board, I would add a special shuttle for this circumstance, with better thermal shielding and more radiators. The most difficult part would be finding a place to dock it without making massive modifications to Boundless.

At periapsis, looking from the rearward cupola. It's protected by the nose cone, which is itself glowing red. Quite terrifying

Here the cupola is open to gaze at Kaywell. Only for a few seconds, least the kerbal will go blind and the cupola will melt

So, I reloaded and repeated the Shol flyby with a different trajectory. The new plan is to change solar orbit so that Wolda is at apoapsis. This way I'll have an Hohmann trasfer for it, and it will reduce cost. It's still going to be super duper expensive, but a lot less than coming directly down from Tyepolbynar would have been. Nothing to do about that, this deep into a gravity well every maneuver is going to cost a fortune.

I also scrap the idea of taking a sample from Shol's atmosphere. There are two problems.

The first is, passing that close to Shol would give a gigantic gravity assist. If I take that assist to slow down, I will crash into the sun. If I take that to accelerate, I will get kicked out of the solar system entirely. If I go for a polar orbit, it would be too expensive. Still, I could have tried to get kicked into a Kaywell escape trajectory to intercept another gas giant on the way out. The other problem is that escape speed on Shol is nearly 30 km/s. On Jool you enter atmosphere at 9 km/s and you can take a small dip to do some quick atmospheric science. Going three times faster, in a place that already puts the ship close to overheating before it even starts aerobraking? I didn't even try.

The new trajectory after Shol flyby. The apoapsis is just right, and the periapsis is just out of the fiery death zone^TM

More spectacular pictures of the stars, Shol, and a comet

The maneuver to reach Wolda

Now I can't take any more gravity assists, can't use Oberth effect. Ok, wrong. I could have made a retrograde burn at Shol periapsis, if properly arranged I could have raised solar periapsis to Shol level with minimal cost, instead of having to pay 3600 m/s as shown here. It would have been difficult to get the angle right, but would have been nice to try. As many other things, by the time I thought of it, it was too late, and I wasn't going to reload hours of game if the deep fuel tanks of Boundless can still carry me to the end.

So, Boundless will now raise periapsis for 3600 m/s, putting it at the level of Shol. This drastically reduces the chances of hitting the giant planet by accident - orbital times are around 10 days this close to the sun, and Shol has a large sphere of influence, so an encounter is only a matter of time. Raised this way, I know Shol will cross my path only in 100 days, which is more than enough to land on Wolda. Also, if I don't pay some of the price with Boundless, Traveler won't have enough deltaV to reach Wolda and return. At this point, I still need 4 km/s of intercept deltaV to get around Wolda. Traveler has enough, though it needs the extra fuel tank. And those 4 km/s can't be reduced in any way.

Boundless came this far relatively cheaply, but now it's about to drain two thirds of its remaining fuel. Also, another comet

I have to open a tangent and talk of comets. Why is there always a comet near the sun? Normally comets only spend a tiny fraction of time in such a region.

The reason, I ascertained, is that the low orbit of Kaywell is cluttered by massive bodies. So the game spawns a comet, and throws it near the sun. At this point, the comet interacts with the gravity of Shol or Limnel, and three things can happen. It can be ejected out of the Kaywell system entirely. Or it can crash on a surface. In both cases, the game senses there are no comets anymore and spawns a new comet. Finally, the comet can get captured in a close orbit, in which case it will continue orbiting close to Kaywell, being active the whole time. Until eventually it crashes on Shol or Limnel, and the cycle begins anew. Either way, there's an active comet most of the time in the Kaywell system. A comet getting kicked by Shol into a high orbit is rare - though when it does finally happen, the game will stop spawning comets for a few years, until the comet has another chance to return to periapsis and get destroied.

Anyway, it just means I get to see awesome images of comets. Good.

It also means my plan of seeing a comet was probably doomed from the start. I don't want to imagine the intercept deltaV on an object with a chaotic near solar orbit.

Traveler sets course for Wolda

When I made this plan, I totally did not account for Traveler's thermal resistace, or lack thereof. In particular, while it's made with heat-resistant parts, and it has a narrow profile to turn to the sun, it lacks the radiators. Well, as you can see from the picture, at solar periapsis it gets 954 °C internal temperature in the crew pod. Limit is 1000. So, the plan works, barely.

I wonder how the crew is doing with 950 °C inside their cabins.

4.3) Weird, yet beautiful

Spoiler

The hard work done in the previous section, all that's left to reach Wolda is a really long burn. Made more complicated by the game not seeing an intercept even when Traveler would be passing inside Wolda's SoI.

Approaching Wolda

Wolda has a peculiar elongated shape. It's obviously a long piece of rock, small enough to not be circularized by its own gravity. The two lobes extending outwards suggest this may be the result of two contact binaries, or a contact ternary if you want. Though I'm not sure those can form so close to the sun, where trajectories are very fast.

It's shape is too long to be a potato. It actually resembles... how can I put it without triggering the automatic censor... a piece of human feces. However, I like it. A lot. The rest of this subchapter is just a photo gallery of Wolda.

After roughly a minute exposed to the sun here, a kerbal will die of overheating. There's still enough time to plant a flag, though

I didn't bring Cigar because it wasn't needed in the minuscule gravity. However, Wolda looks like an interesting world to circumnavigate with a rover. So, when I periodically delete the old saves, I kept the one just before detaching Traveler, so I could get Cigar and perform a circumnavigation. By the time of this writing, I started the circumnavigation and I'm halfway through. It will get its own chapter later.

4.4) A convoluted return

Spoiler

I accomplished all I could down here. Time to move out. First, Traveler has to return to Boundless. It will take four more km/s, fully within its fuel budget.

Trajectory for rejoining Traveler with Boundless, well before Boundless crashes on Shol

Obligatory shot of Traveler with a comet

I have to point out, while Traveler can resist the heat if pointed with the engines towards the sun - and it can also resist it long enough in sideways orientation to perform its prograde/retrograde burns without overheating - it can explode if left too long oriented with the long side exposed to the sun. Which happens as the orbit turns around. Preventing this would have required stopping the time warp roughly every day to reorient the ship. As the rendez-vous is planned in over 40 days, I took the easy way out and activated immunity to heat in the cheat codes.

With Boundless whole again, I use the gravity of Shol to replicate the inward trip. In order to raise solar apoapsis to Tyepolbynar, I have to lower solar periapsis to increase intercept speed on Shol. But I didn't need all the 3600 m/s I used previously; 580 m/s are enough. Makes me think, I was probably wasteful previously. Too late to fix it now. I will have to pay almost 500 m/s to fix the inclination, though.

The Shol gravity assist to Tyepolbynar

Another awesome cometary pic

Coming from the very inner system, Boundless has a huge intercept speed on Tyepolbynar, too much for a direct capture. Ok, maybe not, maybe the giant Oberth effect from the giant planet would have been enough; I didn't try. I went for a Mesbin flyby to raise solar periapsis and reduce intercept speed. In any case, those gravity assists are almost free, and I still have 40 years worth of life support.

Trajectory from Tyepolbinar to Mesbin. Will need refinement on the Mesbin exit trajectory. The 448 m/s burn is the plane change

I use Mesbin to raise solar periapsis perfectly for a Hohmann transfer to Tyepolbynar, reducing intercept speed

It was a big change in trajectory, that required passing very close to Mesbin: 500 km, to be precise. I went for it, then crashed on the ground, remembering too late that Mesbin extends as high as 970 km above datum level. I compensated by using Derbin too; it would have been very easy, as the giant moon was in the way. The only problem is that the game refused to see the intercept with Derbin; I don't remember how I fixed that.

The planned trajectory required almost a U-turn around Mesbin, accomplished with the help of Derbin

You can see Shol as four pixels over the tail of the comet. I already have many better comet shots, but I thought: how often do you see a planetary transit over a comet tail?

Finally, from this Hohmann trajectory Boundless reaches Tyepolbynar after some orbits

I'm... not sure what the 3 km/s intercept speed is for. It cannot be an intercept speed for low orbit on Tyepolbynar, because I know that just 1 km/s above the escape velocity is enough to reach Shol, such is the Oberth effect. Which is also what make me think I could have saved more fuel on the way inward. No, getting captured in low Tyepolbynar orbit is not a good idea anyway, because then it takes 7 km/s to escape the giant planet anyway. Still, I can't understand why 3 km/s. Maybe I was trying with capture into a higher orbit. It's certainly not intercept speed on a moon, it's too early to plan for that.

Anyway, I subsequently spent 150 m/s at apoapsis to remove inclination. It's a lot easier to get an intercept on the moons this way, and Tyepolbynar has two that are very helpful for capture.

4.5) Multi-step aerocapture

Spoiler

I'm finally getting close enough that I can start planning capture. I could get captured with a low periapsis using the massive Oberth effect from the superjupiter-class planet, but then I'd have a large intercept speed on the moons. But as I mentioned, two moons are very helpful.

First is Imterril. It's slightly bigger than Laythe, with a much bigger and denser atmosphere. It can be used for good gravity assists; as for aerobraking, coming from an interplanetary trajectory will be too fast for Boundless. The second one is Tannor. It's slightly smaller than Vall, but it has a very thin atmosphere - one tenth of Duna. Too thin for parachutes to work, but it should still be enough to aerobrake, and the low gravity means I'll be able to come in with a large velocity.

What made me pick a gravity assist on Imterril was simply a matter of practicality. Boundless was already on a trajectory for a close passage to Imterril, and could get there with a minimal correction. While Tannor was on the opposite side of the orbit, and I couldn't find a cheap way to speed up or delay Boundless for six days. In fact, I went for two gravity assists on Imterril.

Capture around Tyepolbynar; First a gravity capture from Imterril, followed by another passage on Imterril 20 days later to lower apoapsis

This picture of Imterril and Tyepolbynar is one of my all time favourites. Real beautiful planets. The comet and the awesome spaceship help too

Close up of Imterril and Tyepolbynar, at this distance they look the same size. Shol is also visible on the right of Kaywell

Performing some EVA experiments

More of Boundless passage over the clouds of Imterril

Now Boundless got captured around the gas giant, but it wants to reach Tannor. The second flyby was meant to provide a good trajectory for that moon.

Trajectory for Tannor

Boundless, on the blue path, will make a 24 m/s course correction to refine the next passage over Imterril, in 9 days. This will ensure meeting Tannor along the green dotted trajectory with slightly over 2 km/s intercept speed. Quite high, but given Tanor's small size, it will translate to roughly 3 km/s of speed entering atmosphere. And that's within Boundless capability to survive. I could find a better trajectory that would minimize intercept, as the picture shows I'm far from an optimal Hohmann transfer. But what the hell, I wouldn't build an aerobraking-resistant mothership if I didn't intend to use it for hard aerobraking.

Approaching Tannor

A cold, icy planet this close to the sun? Right next to Imterril, where the flavor text says the atmosphere is superheated steam and the ocean boils? Hard to swallow.

Boundless at periapsis. Aerobraking periapsis was chosen by trial and error as the lowest it could survive

I lost some 400 m/s from that. Now, as Boundless crosses Tannor's orbit, I'm sure it will meet the moon again soon. And it will finish the job; now that it's slower, it can afford to go lower.

Indeed, a 56 m/s course correction puts Boundless on track for another passage

I could probably go cheaper if I really tried, but I still have over 2 km/s, and on Tannor I can refuel.

Soon, though, I found a flaw with using Tannor to aerobrake. The atmosphere is so thin, even passing at sea level Boundless only loses 400 m/s. And that's by picking a 7 km periapsis and skimming the mountains.

In fact, here I was just too low and crashed on the mountains instead

I later found out there are mountains up to 15 km high on the equator of Tannor, I was just lucky to never find them.

Anyway, long story short, I had to take five or six aerobraking passages. At least each one was slowing me down relative to Tannor. It took the best part of an afternoon, but Boundless reached safety over a small planet suitable for refueling after its trip to the core of the Kaywell system.

The last aerobraking passage, by now Boundless and Tannor's orbits are quite similar. This time it was not necessary to go down to 7 km

Edited July 27, 2023 by king of nowhere

[king of nowhere]

Part 4B: Very hot wheels

In this spinoff I reload back to bring the Cigar rover to Wolda. I figured that since I'm going to circumnavigate the minor body, I may as well do it sooner than later.

Probably the first entry in the Elcano challenge where ship overheating is an actual issue.

Spoiler

To get to Wolda, I reloaded from just before sending Traveler to the minor body. Instead of sending Traveler alone, I sent Cigar with it. I left its fuel tanks mostly empty, since it takes very little to orbit this place.

Landed on Wolda. Partial overheating is normal in the sun, but it does not reach dangerous levels

The suns don't look that big from this perspective

Wolda has an elongated shape, looks like a contact binary or even ternary. The game is not equipped to recognize those complex shapes, much less handle the resulting gravitational field, so for its purposes Wolda is a regular body with two very, very tall mountains. Cigar landed near the top of one lobe, so the first part is all going down.

Going down from the first lobe towards the center

Driving in this low gravity is slow. I must deactivate reaction wheels, then accelerate. The rover nose will tilt upwards, so I'll have to stop after achieving barely 2 m/s. Reaction wheels will help me stabilize the asset, then when the gravity slowly pulls the rover back on the ground, I can accelerate a bit more. Until I reach around 6 m/s, then the rover spends too much time airborne to keep accelerating, and it will slow down with further bounces.

This would normally be a very slow process, but it is helped by some foresight (or lack thereof, you decide) from the modders: you can time warp all the way to ground level. On one hand this makes crashing on the ground more likely. But for me it's a huge boon, because once the rover gets some speed, I can time warp the several minutes it takes to return to the ground. Even better, while time warped I can save the game regardless of distance from the ground. Normally saving the game requires stopping the vehicle, which imposes a hard choice between losing time to brake and then accelerate again, or risk losing even more time in case of accidents. Here I could save often.

A related problem is planting flags. I decided, since this world is small, I'd plant one every five km. But stopping to plant would really break the rythm of accelerating the rover. So I opt, as I've done other times in similar instances, to send out the driver with the jetpack to plant the flag and rejoin the rover in mid-jump.

Val planting a flag in such a fashion. I didn't consider that this close to the sun, kerbal overheating could be a problem

Returning to the rover, just before heat death

Outside of the rover, Valentina has roughly one minute to survive. Taking those jumps takes a bit of time, especially when the rover is hundreds of meters above ground, so the time to plant a flag is tight. For the first couple flags I just activated the "ignore overheating" cheat; meanwhile, I asked in the elcano challenge thread if that would be ok. Since an answer did not arrive timely, I decided to just try harder to plant flags fast enough. Being able to save just before going out helped a lot, I could afford to risk reloading. After a while, I got good at planting flags quickly.

Getting close to the neck region

A view from above of the lobe I just left. You can see the flags I planted, though the high illumination makes it difficult

The second lobe looms like a massive, near vertical cliff

Another problem I faced was light. As you can see from the images above, it's all oversaturated and you can hardly make out where you're going. Which is bad twofold; first, I want to enjoy some scenery and take some nice pictures while running a circumnavigation, and I can't in those conditions. And second, while Cigar is moving slowly, it's still fast enough to explode the docking port or the engine if they touch the ground before the wheels. And with the ground being all irregular, you can't just keep the rover straight.

Here I tried to lower light level at the minimum possible; it's still oversaturated, except for the parts in complete darkness

I didn't expect increasing light even more to help. Case in point

And here with normal light level. Hardly makes any difference with the -100% setting

I managed the light issue by waiting dawn/dusk to move. In those times, you have some decent light.

No, going by night did not work either. When the sun sets, you have total darkness, and not even light amplification helps.

About to climb the massive wall

At least with the sun in the right positions there is good visibility

75° slope

Despite being almost vertical, this cliff wasn't too hard to climb. The gravity is very low. The only problem is to keep the direction upwards and onwards. Sometimes I accidentally let the rover bounce away from the rock wall, and in that case it was faster to reload than to see it fall down kilometers before touching the ground again.

The second lobe, in some detail

Even 5 m/s is enough for a significant suborbital jump, especially at this altitude. Also, some data on Wolda shown

Wolda has a nominal radius of 9 km, but the two lobes both extend 19 km above zero level. I was not able to find the highest point on Wolda, because the perspective on top of a lobe is all skewed. The neck region is in the 4-6 km range. Which means, since low space begins at 6 km of altitude, that it's really hard to find a place to conduct low space science.

Close enough to the top of a lobe

Going down, this side of Wolda is much more cratered

More detail on the craters

Here I'm already going up the other side. This lobe is less vertical

The ground is partially transparent near the top of the lobe, you can see stars and the rest of Wolda through it

Cresting the top, from this high I can fall a long distance. This jump would deposit Cigar near the first flag. But I used the rocket to slow, I didn't want to skip too much ground

Getting close to the first flag

Reached the first flag

This concludes the circumnavigation of Wolda. It took several hours of real life time. Now back to the main mission.

Edited August 11, 2023 by king of nowhere

[king of nowhere]

Part 5: A super-Jool with a super-Laythe

Boundless explores the Tyepolbinar system.

The moons of Tyepolbynar. Do notice the relatively high orbital speeds, especially for Jifgif, and that Etrograd is in a retrograde orbit

5.1) Not quite like Laythe

Spoiler

First thing I did when Boundless arrived on Tannor was refuel. Halfway through refueling I started sending missions to the moons, interspersed with more refueling. But for practical purposes, I'm saving all the refueling last.

First moon to be explored is what looks the more interesting: Imterril. Imterril is a water world somewhat similar to Laythe. It has a similar gravity, and it's covered in ocean. Unlike Laythe, it has no islands whatsoever, only water, to the point that its whole surface is a single biome, called boiling ocean. The atmosphere is also a lot thicker, extending to 182 km of altitude and reaching 15 atmospheres of pressure at sea level. Not that it really matters when I have a nuclear-powered plane to fly out of the dense part; Arrowhead will be able to climb until the pressure is around 0.4 atmospheres, then it's not much different from orbiting Laythe.

Or so I thought. Big mistake. But let's go with order.

Imterril is fairly close to Tannor in orbit, and you can get some decent Oberth effect from both bodies, so the transfer is cheap. You can also aerocapture on both bodies, so the transfer is even cheaper.

Tannor to Imterril; 380 m/s to leave Tannor in a Hohmann transfer, 30 m/s to capture. Wow, it's rare that I actually get to use actual Hohmann trajectories

Traveler leaving Boundless behind, with Boundless passing in from of Tyepolbynar

Into Imterril atmosphere. Arrowhead can easily take 3 km/s on capture, it will be fine

Imterril is quite pretty. Too bad it's completely featureless; it could be interesting to explore with a submarine

For the sake of curiosity, I tried to alt-f12 a submarine in place. Here's what I found.

A submarine on the bottom of the oceans

Extremely underwhelming. The submarine is sitting on the bottom, it's not moving anymore, the altimeter says it reached bottom, but there's nothing. I guess the real bottom would be deeper but the game stops you at -10 km? I try to move Rimanna down on the ladder, but she can't move further. Either that, or the surface is transparent.

Close to the surface, with some science reports. Notice the 15 atmospheres of steam; this implies a water temperature of roughly 200 °C

Do notice the 15 atmospheres of pressure, and the plane being capable of sustaining flight at 23 m/s in those conditions.

Also do notice how I got two different surface samples. One when I had Raberta collect it standing above Arrowhead, and one when Raberta was in the ocean. Does this mean you can take separate "landed" and "splashed down" samples just by climbing on top of another vehicle? If so, there are options I missed in my Jool 5 science run. I'm definitely giving a thought on running another one. Later. In a few months, after I'm done with the whirligig world.

Ok, Imterril looks good from afar, but the surface is literally exactly identical everywhere. I have no reasons to explore or anything, so it's back to orbit. And here I run into the first issue: Arrowhead can't take off.

Arrowhead stuck on the water surface. Notice how drag (which includes propeller thrust) does not exceed 100 kN, and how the propellers are limited at 75 rounds per minute

In normal conditions, Arrowhead can't take off from water. It doesn't even come close. But those are not normal conditions, we have 15 atmospheres of pressure here! Surely that gives my wings so much lift, and my propellers so much power, that they can take off in any condition. I'm pretty sure Arrowhead could fly up vertically in this atmosphere!

Well, it was a reasonable assumption; so reasonable, I didn't think to test it. Indeed, with 8 atmospheres of pressure it would have worked: Arrowhead did fly up vertically at higher altitudes. The problem is that, past a certain density, the propellers face too much resistance. They are supposed to go 460 rounds per minute, but their speed goes down, and the thrust goes down too. I didn't know, but past a certain density the propellers are less efficient. In normal presure Arrowhead can achieve 200 kN of power forward, but here it's limited to half of that. And even though I could keep flying at 23 m/s earlier, that speed, when stuck on the water surface, is not enough to take off.

I almost lost a couple months of progress as the grand tour was made unfeasible. I was saved by a coincidence. I picked the engines for Arrowhead based on some traits; they should be optimized for vacuum, because Arrowhead is only supposed to use rockets in the high atmosphere. They should have high thrust, to propel this plane out of the atmosphere. They must be compact, to keep the aerodinamic profile. And they must have an aerodinamic profile. I don't know if the shape of the Darts actually make them less draggy in atmospheric flight, or if the game doesn't simulate that well. I suspect the second, since I've seen some of the low mass records and they involve things with lots of flat surfaces that somehow fly better than an actual plane. Anyway, the Dart engines have good vacuum Isp, good TWR, and they fit with the fuselage. I picked them for those reasons.

By lucky coincidence, the Dart is also the one single engine that keeps working at 15 atmospheres of pressure. A condition I never thought would see their use. Even the Vectors and Mammoths, a normally safe choice for Eve ascent vehicles, completely stop working above 12 atmospheres - and are pretty much useless anyway above 8.

Sure, in such an atmosphere "working" is a relative concept; the Darts have 88 s of Isp, and they give Arrowhead a TWR of 0.5 in the local gravity. But adding their meager thrust to the propellers is enough to take off.

With propellers and darts Arrowhead can reach 40 m/s on the water surface

Which is enough to take off

This stunt burned 10% of the fuel, worth 250 m/s in vacuum. An enormous amount of take off from water once, but it's not going to hurt too much for orbiting. Imterril is similar to Laythe, and Arrowhead can orbit Laythe with almost 1 km/s left. I didn't expect any problem.

Reaching up to 70 km, pressure 0.37 bar. The propellers can't climb any further

Time to start rocket ascent

But Arrowhead will run out of fuel well before coming out of the atmosphere

Ok, it's my fault once again for making assumptions without testing, and especially without reading the fine print. Imterril has the same gravity of Laythe, but it's got a 50% bigger radius. This translates to a higher orbital speed. It also has a higher atmosphere; on Laythe, Arrowhead must climb up 45 km upward; on Imterril, 110 km. High atmospheres in high gravity are the worst; if you fly up vertically you take a lot of gravity losses, if you take a steep gravity turn you take huge drag losses. If you go faster you increase drag, if you go slower you increase gravity drag, and the outcome is a big "you're screwed" for your ship. Arrowhead could fly away from gas giants Urlum and Neidon, but those planets, while very big, had much smaller surface gravity, which made gravity losses more bearable.

None of those factors by itself is insurmontable. They all add a few hundred m/s of requirement. But taken all together, with Arrowhead already having spent some fuel to leave the surface, they become too much.

I tried a half dozen times (stopping the rotors and braking before saving avoids propeller damage on reload) with different ascent profiles; all was in vain. Arrowhead always comes close; the best I could manage was 50 km periapsis. But it never goes orbital.

But ok, I can totally salvage this. Arrowhead can go suborbital, and stay out of the atmosphere for several minutes if it goes for a high apoapsis. Traveler has a lot of fuel. I can have Traveler grab Arrowhead from a suborbital trajectory. It's been a while since I had to try this maneuver.

However, right now Traveler is in an elliptic orbit. I have to reload from splashdown and circularize Traveler first.

Now I have to time the take off. I want Arrowhead to be slightly ahead of Traveler. This way Arrowhead will fly up at speed slower than orbital, and Traveler will reach it. I only have a few minutes for a rendez-vous, and I must circularize with Traveler's low thrust before entering atmosphere again. And it's not easy to get the right time, because Arrowhead must launch from sea level and go up 70 km. Indeed, I was too late, and Traveler surpassed Arrowhead. Now I have to fly around another hour, until Traveler goes in the right place again.

Except... This time, I managed to climb further upward than the previous one

I'm not sure exactly how, I suspect it was a matter of degees of attitude. Be as it may, I was launching from 71.5 km, and now I am at 74. Those 2500 meters are not much, but the atmosphere is 20% thinner at this altitude. And Arrowhead was missing orbit by a smidgen already. Worth trying.

I'm still not completely out of the atmosphere (182 km), but I plan to use the RCS to gain those few missing m/s

At this point I realize I crewed Arrowhead with a pilot and a scientist, no engineer. My cunning plan of installing the RCS and using it to gain those few missing m/s is thus doomed to fail, because the RCS system is currently stowed inside the crew cabin for reduced drag. Arrowhead could probably stay orbital after a short passage so high in the atmosphere, but Traveler is badly placed, it can't rescue Arrowhead anytime soon. On the plus side, if I managed to almost orbit this time, at the first attempt, I can surely do better.

Indeed, orbit reached

Now Traveler can pick up Arrowhead and return to Tannor. No more problems.

Return to Tannor. The 700 m/s are mostly to escape Imterril's gravity

Back to Boundless

When I was first planning this grand tour, I considered the planets one by one and made a list of those potentially problematic - those that required special testing. I did try the parachute-assisted landing on Oshan and other planets. I did test that Cigar was powerful enough for the biggest airless worlds. But in my list of testing, Imterril was never included. I just assumed, fly up to the edge of atmosphere, and from there it's no worse than Laythe.

It's funny, I've been comparing Imterril to Laythe all this time, expecting a relatively simple target; I went to check @Jack Joseph Kerman report of his own grand tour on this system, and he keeps comparing Imterril to Eve, as it is bigger, has higher atmospheric pressure, and it's more massive than Kerbin. If I had noticed all that, I'd have certainly put more planning into this part of the mission.

An oversight that almost costed me dearly, but Arrowhead was just barely capable enough to get me out of this mess.

5.2) Two lobes is better than one

Spoiler

Next target is Jifgif. No, I have no idea how it's pronounced.

Jifgif is a minor moon orbiting very close to Tyepolbynar. The close orbit with the planet will make this an expensive trip, but Traveler should have enough deltaV.

Traveler is fully loaded, but in a show of confidence I didn't bring the additional heavy stage that would increase it's deltaV by a few more km/s

The route to Jifgif will involve gravity assists from Imterril

For precision, 485 m/s to leave Tannor with a periapsis lower than Imterril, to increase intercept speed on Imterril, and an additional 120 m/s at Imterril periapsis, because even that wasn't fast enough to reach Jifgif. Intercept speed will then be 2750 m/s. For the return trip, 2750 m/s will reach Imterril again, and from there it's all gravity assists and aerobraking. I should be fine.

A direct trajectory from Tannor to Jifgif would have costed over 5 km/s, leaving Boundless with no fuel for the return trip.

The burn over Imterril

Jifgif passing in front of Tyepolbynar

It's a contact binary!

Some good views of this minor moon

Jifgif is roughly 40 km long and 20 km wide. It's a bit smaller than Wolda, but it's got a higher surface gravity, due to being denser.

Landing, and some science reports. The thing about radiations make me think that, if kerbalism had been compatible with this planetary pack, I would not have been able to perform manned landings here

Jifgif is so nice, it's basically an improved version of Wolda; similar shape, but smaller, and with more gravity, and prettier. The light oversaturating everything was a real issue on Wolda. Also, Jifgif has actual biomes (large lobe, small lobe and neck), making it feel less pointless to move around.

I want to circumnavigate this world too. And I did.

But it will get its own chapter. Here we'll time skip to returning to Tannor.

2900 m/s to Imterril, from there it's gravity assists

To be precise, it takes two consecutive assists to raise apoapsis to Tannor

Additional course corrections and rendez-vous left me with very little fuel when I rejoined Boundless

5.3) We can go retrograde the hard way, or the long way

Spoiler

Next target is Etrograd, named for its retrograde orbit. Unimaginative name. They could at least have called it Edargorter.

Even though I'm pretty far from Tyepolbynar, the massive gravity of the massive planet is still strong here, therefore a 150° plane change is still very expensive. Like, 7 km/s expensive. Fortunately, there are tricks for reducing the cost of a plane change.

First trick is to raise orbit, so the ship would be slower and a plane change cheaper. I simulated using an Imterril assist to go as far as possible from Tyepolbynar; that's 800k km; the SoI of this planet is still relatively small due to its proximity to Kaywell. So the orbit is slow, but not as slow as I'd like. The cost of the plane change is 2 km/s.

Simulated trajectory for Etrograd by raising apoapsis and changing plane

Add an estimated 500 m/s for capture, a return trip should be within Traveler's fuel budget. Barely.

It would be possible, theoretically, to use gravity assists. However, it's virtually impossible here. To invert the orbit, I'd need a crazy intercept speed on Imterril, and how would I achieve such speed? I'd need to bounce between two planets, and besides Imterril there's nothing big enough around here for this task. No, Tannor is not big enough.

I still have an option, though: escape Tyepolbynar orbit entirely and enter it again retrograde.

Escaping Tyepolbynar to enter retrograde

The outcome of such trajectory. It would reduce inclination to 5°

Step one is, again, a gravity assist from Imterril (530 m/s to reach) to exit Tyepolbynar. After 250 days I'll return and... things get complicated here. I wanted to achieve a Tyepolbynar periapsis level with Etrograd, to be already properly placed for intercept. But the game is bugging; I move the maneuver slowly, and the orbit changes slowly, until suddenly it changes completely. No, I did not slip with the mouse; it's consistent. The game suddenly gets a wrong orbit. After much trying and many expletives, I had to take this orbit with a 60k km periapsis; it will cost more to raise periapsis, but I can afford it.

Finally, there's the time factor. In that I still pretend I'm playing with life support, and Traveler is good for one year. This trajectory will last 300 days, including further maneuvers for Etrograd; it means on return I'll take the direct route. I saved enough deltaV to afford it. Actually, I was hoping I could also visit Aerious in a single trip.

I tried reducing the number of orbits shown to the minimum, but the game still insists in showing my orbit in 56 years. Do you have an idea how hard it is to find an inclination this way?

Coming back to Tyepolbynar, the game predicts I'll enter in the orange orbit

Except I enter instead in this different orbit. Shows how more the game is bugged

I eyeballed a higher periapsis, though the game didn't help me, and I came close enough to the desired periapsis.

Final route for Etrograd. Not shown here, 430 m/s for capture

60 m/s at Tyepolbynar periapsis for capture into a high orbit. I still have to correct those 5 degrees of inclination, and it costs 360 m/s, the biggest cost here. Then 90 m/s to raise periapsis, thanks to the game for forcing me to eyeball it, and finally 430 m/s for capture on Etrograd. All in all, I spent some 1500 m/s. I have plenty for the return trip.

Etrograd is covered in chasms. It's slightly smaller than Mun

Those chasms form the ridge biome, you can see it here as the brown lines

Landing near one such ridge

A couple of very poignant reports

I did drive a few km to reach multiple biomes, but I didn't find this world interesting enough to explore further.

An hypotetical direct intercept for Tannor would cost almost 8 km/s

To return, I will have to raise apoapsis and change inclination; with close to 5 km/s, it will be easy. And since I'm there and I have enough fuel, I may as well go directly to Aerious.

Actually, going directly to Aerious will cost more time and break the one year time limit for Traveler. But what the hell, I could have done it in one year if I wanted, and I'll only break it by a few days. It saves burocracy.

5.4) The north pole of Aerious

Spoiler

To go on Aerious, I leave Etrograd on a high Tyepolbynar apoapsis (555 m/s), and turn around the orbit (2425 m/s). It's more expensive than it would have been to reach Etrograd because I also have to raise periapsis. Capture on Aerious is more expensive (490 m/s) than capture on Etrograd was, because Aerious is smaller and has no Oberth effect worth mentioning.

Route to Aerious, as described above

Aerious, and its most important science report

One thing tht immediately stands out of Aerious is its north pole terrain glitch, visible from space. I went to check it.

Getting closer to the north pole anomaly

Look at that!

The north pole is comprised of a very tall, very pointy mountain, and an additional terrain artifact in the shape of a bidimensional layer of ground, visible only on one side. Cigar exploded by passing through it.

Descending the spike

And landing. With another interesting report

Going up the spike

The bidimensional spike tops at over 14 km. But I can't balance on it to plant a flag

I instead plant a flag on top of the nearby mountain

It's really pointy

Once more, I don't really care about this planet, and I return to orbit.

This is actually the south pole. Aerious should be renamed Polarterrainglitchious

And the trajectory back to Tannor. A simple Hohmann transfer

One last time over the north pole

5.5) Refueling on Tannor

Spoiler

Boundless was almost empty, it will take a lot of trips to refill. To ease the monotony, I split them between other landings.

Tannor has a very thin atmosphere, as I constantly remarked during aerocapture. It's so thin, the parachutes won't open, I have to use rocket braking. I was worried it would cut deeply into the refueling, but it turns out, 15 tons of fuel are more than enough for that. Factoring in the lowest deltaV cost to orbit, Ice Cream Cone could still bring up almost 100 tons of fuel per trip.

When I needed oxidizer, instead, I'd keep the liquid fuel tanks empty. This way I got 20 tons of oxydizer. Boundless needs very little of that, so two such trips were more than adequate.

Ice Cream Cone performing the deorbit burn

Drag is so low, I can keep the solar panels extended during descent

And landing

The terrain of Tannor proved surprisingly difficult. Mountains everywhere, except where there are craters. Very irregular terrain, more than once I found a slope too steep to land on. Good thing those 15 tons of fuel include enough to go up and land again.

Ice Cream Cone, landed

I am also happy Ice Cream Cone turned out to have a large enough base and low enough baricenter to stay upright in most conditions. Most of those landings were on 15 to 20 degrees slopes.

One of the rare flat bits of terrain, with the sky being especially pretty

Ascent

Seen from the cupola. Too bad I can't land like this, the game tries to reorient the cupola pointing forward if I am in it; even if I deactivate SAS

Ascent, already near orbital speed

Ascent profile is very steep, as would be for a world without atmosphere. Because the atmosphere is so thin, its drag is negligible. On Oshan I was a bit skeptical about the design of Ice Cream Cone, but I'm very happy about it. The shape is perfect for Tannor; on descent, a wide flat base that makes drag. On landing, the base is large, and the baricenter low, so that it stays upright even on difficult terrain. And on ascent, it's wonderfully aerodinamic.

I even landed Arrowhead once, to gather science

Yep. Not needed for the grand tour, but collecting science is a holy duty. By the way, I really don't buy that report. A stone throw from here, there's a planet of superheated steam with a boiling ocean. And here it's below freezing even at the equator? I know albedo and greenhouse effect can make a lot of difference, but this seems way too much.

It took a long time, but eventually Boundless was filled.

Status, ready for the next destination

Edited March 20 by king of nowhere

[king of nowhere]

Part 5B: From lobes with love

This spinoff chapter covers the circumnavigation of Jifgif.

No, I still have no idea how it's pronounced.

Spoiler

I liked Wolda, and I circumnavigated it. I liked Jifgif even more, I couldn't not circumnavigate it too. This time, knowing I'd do it eventually, I decided to take care of that urge immediately. This way, at least my screenshots were kept in order.
Cigar's landing point was on the edge of the small lobe. I decided to start by crossing the lobe, rather than facing the plunge downhill immediately.

Of course, Jifgif being a small body, Cigar starts jumping as soon as it picks some speed

And it could pick quite some speed. At least for a body this small

reaching 10 m/s on flat on a body smaller than Gilly is no small feat. I learned to deactivate reaction wheels and accelerate mid-air, to make my wheels spin, so that the rover will accelerate in its short contact with the ground.

Just like on Wolda, I can time warp freely during jumps, which simplifies things immensely.

The terrain on top of the lobe is chaotic mountain terrain. Not that it has much effect on my actual trajectory. I like the terrain colors

A visual glitch, with part of the ground being visible in mid-air

Another visual glitch, with Tyepolbynar being visible through the rock. Seethrough mountains!

Soon enough, I reached the end of the lobe and started the plunge downward. Jifgif has more gravity than Wolda, bausing Cigar to pick more speed.

A fall the lenght of a whole planet. 7 km, more precisely

Reaching as fast as 30 m/s

To plant flag, I again went EVA with the rover moving, just like on Wolda. Except here, I skipped two flags, I was too busy trying to survive during this fall. I'm not sure how I managed going down the next lobe, maybe it was less steep.

Finally safe on the neck. The lobe I just left is a massive cliff from this perspective

Without light amplification, shaded areas are completely black. I prefer to use natural light when possible, so I took a pause and waited for the sun to move accordingly

I found rocks! Those ones are purely a visual effect, Cigar can pass through them all right

I experienced a similar behaviour on OPM bodies: at high elevation, there are no rocks. You only find them down below. The limit seem to be around 10 km. Makes me want to go in the lower crater on Priax, it's probably the only place on that moon, where I have some hope of finding some and seeing how they're made. I have no idea why rocks on some planets have collision enabled, and in others they don't.

Now going up the next lobe

While looking back at the old one. This new lobe has a sort of collar, at least from this side

Finally making it up the large lobe

A weird trait of Jifgif is that it's not tidally locked to its parent body. Tyepolbynar moves across the sky as this small body spins asyncronously.. I can envision the formation of this contact binary being a recent event, that disrupted the previous gravitational equilibrium. On the other hand, contact binaries form from a soft collision, and this close to a gas giant orbits are fast; I don't think one such body could have formed here.

This lobe also has chaotic, but relatively flat terrain. Flat in a large scale sense, at least

And the ball on the horizon is Imterril

An accident while returning from planting a flag. I had a similar instance on Tal

So now I have the dubious distinction of being the only person responsible for all running over accidents ever happened in two separate celestial bodies. I went to check, and last time it was Bill; at least I didn't run over Bob twice.

This spike is Jifgif tallest mountains, at over 12 km. Which is only a couple km more the average for the top of a lobe

Low space on Jifgif started at 12 km, so while you couldn't have a low orbit and be perfectly safe, taking low space science is still a lot easier than it was on Wolda.

Another instance of racing the rover after planting a flag. This time the rover had gathered some distance

Descending from the large lobe, the small lobe is already well visible

Another instance of catching the rover on the fly

On the neck again, about to climb up the small lobe. The first flag is near

Climbing up

And finally reaching the first flag

Jifgif being smaller and with higher gravity than Wolda, its circumnavigation was shorter and faster. It took me two days of real life time, though I have no idea how much time I effectively played in those days.

[RevanX_LSR]

i would like an Imterril circumnavigation. It’s fun, and there are lots to see!

 

Thats obviously a joke. Anyway, that imterril ascent was crazy!

[king of nowhere]

4 hours ago, RevanX_LSR said:

i would like an Imterril circumnavigation. It’s fun, and there are lots to see!

actually, I could do it easily enough.
land. point east. activate propellers.
alt tab the game in background. return after a few hours.

i wouldn't even have to worry about posting multiple screenshots for different locations

amazing how a planet can be so nice from orbit and so boring once landed

[Nazalassa]

On 7/5/2023 at 4:25 PM, king of nowhere said:

0.6) Phoenix heavy landers

  Hide contents

For the two superEve planets, I needed something with propellers to clear the atmosphere, plus a lot of staging to provide the almost 7 km/s required after that.

I also decided I wanted to include something nice. Not just a descent/ascent vehicle, but something with a living space that could work as a mobile science base for a prolonged time. So, a plane with a crew habitat that could be dropped to get a lighter plane, that would then drop the wings to get the final rocket. With a relatively low mass.

The hardest part was balancing everything so that the center of mass and center of lift were correctly positioned at every step.  Protecting this baby from high speed atmospheric reentry at 5 km/s was also no small feat. I called it Phoenix for all the flames involved in the process.

Phoenix, with the thermal shields and umbilical connecting it to the mothership

Phoenix, as it lands on a planet, ready to fly around and explore

Phoenix, rocket part. TWR (RSP in my italian game) is relative to Derbin, roughly 2.17 g

May I ask why the pictures of this vehicle (and only it) were taken in the level 1 SPH?

Anyway, I've wanted to do a big mission with a mothership and stuff for a while (I mean, how can one transport a rover all around the system without a mothership?), and I think this mission report gave me what I was missing: motivation. Since I'm back to KSP, it's probably the next thing I'll work on. Probably because what I called "mothership" before is like a tenth of Boundless, if not less, and now I really want to have a vessel that's larger than the VAB. And a refueller. And "stuff". I apologize for the small unreadable text, and have a good day.

[king of nowhere]

4 hours ago, Nazalassa said:

May I ask why the pictures of this vehicle (and only it) were taken in the level 1 SPH?

There is a bug that occasionally causes the game to think i have level 1 structures. If I am in the vab and i click to change to the sph, the game reverts both to level 1. Only way to fix is restarting the game. 

It generally happens that when i open a report i forgot some pictures of the vehicles. So i open vab and take all the pictures i'm missing. When i move to the sph, it triggers the bug

[king of nowhere]

Part 6: Small worlds

After a doomed attempt to find a trajectory for Fophie, Boundless visits Wers, Egad and Rik in one go, before returning to Oshan to refuel. All were fairly easy targets.

This picture encompasses most of the Kaywell system, and all the worlds Boundless visited or tried to visit in this part of the mission

6.1) I spent afternoons looking for that transfer!

Spoiler

Fophie is getting close to apoapsis, now it's a good time to look for its transfer. Fophie is basically a comet, in a highly inclined, highly eccentric orbit. Visiting such bodies is cheaper near apoapsis, as the large radial and normal components you always need are minimized.

The current position of planets as I seek a Reander flyby. The orbit of Fophie is seen laterally as the brown line cutting the screen vertically - most notable as it crosses the orange orbit of Gememma

Still, that massive plane change is too expensive, I need a gravity assist for it. And I have several choices: I could use Mesbin, or I could use Reander, which will cross Fophie's orbital plane in a few years. Or maybe I could even turn my orbit polar around Tyepolbynar.

The whole business is made more complicated by needing to find a good way to leave Tannor - which is just deep enough into Tyepolbynar gravity that it costs a fortune getting out, but shallow enough to avoid any significant Oberth effect. I explored so many attempts to get gravity assists on Imterril. The task was further complicated by Boundless lagging the game hard - not kerbalism mothership hard, but still hard - making all operations take longer.

Eventually I realized I was getting nowhere with the Imterril flybys, and I'd just have to try a direct route to Mesbin or Reander. Then, once I confirmed that it works, I can look to make it cheaper with Imterril.

Efforts to use Tyepolbynar were frustrated by the faulty encounter engine, as shown in the picture.

Tyepolbynar has a SoI of 800 Mm, so the game is showing an impossible orbit. No way to know what the ship would actually do

The idea was to eject at low speed from the gas giant, then enter it again in a polar orbit - from afar, it would take very little fuel to make sure to pass over the poles instead of the equator - and burn at periapsis to use the massive Oberth effect of Tyepolbynar to gain inclination. In theory it works, in practice getting the timing right - leaving Tyepolbynar, finding it again as it crosses the plane of Fophie, with the right inclination that a moderate burn will give the right orbital inclination - is ridiculously complex. With the game engine not cooperating, I have no hopes. Even had it worked, the amount of prograde speed required to get the proper solar apoapsis would have likely been too high anyway.

Mesbin was quickly discarded: it's not big enough, even a close polar passage won't give me near enough inclination.

Reander was always the most promising target, as its high solar orbit means cheaper inclination change and cheaper intercept on Fophie; though Reander is far enough that just getting there on a high speed trajectory will cost a fortune. Here, I was again frustrated by the game engine failing to properly calculate intercepts. As the close approach inched closer and closer - as shown in the image at the beginning of the subchapter - it would suddenly disappear and mark another completely unrelated approach 30 years in the future.

Starting from Tannor, that orbits slowly around Tyepolbynar, further exacerbated the difficulty. I should have cheated myself out of the moon for ease of simulation.

I really spent several afternoons calculating trajectories, never being able to actually get an intercept on Reander to check the cost of such a trajectory. Eventually, I realized that my whole basic assumption was flawed from the beginning: Fophie is rotating in the wrong direction.

Why I could have never found a good Reander-Fophie transfer anyway

I need to go upward after Reander, if I want to meet Fophie at a low enough speed within a reasonable time. But right now going upward would put me in a retrograde orbit compared to Fophie.

Ok, Reander has an orbital time of 29 years. In 15 years it will be properly placed to slingshot Boundless to Fophie. In the meanwhile, I will spend my fuel visiting some minor targets that pose no special difficulty, but will need to be visited eventually. Starting with Mesbin's trojans Wers and Vizea. And finally I will return to Oshan (the moon of Valyr) for refueling, it's going to be a lot cheaper to get to Reander from there.  As for Fophie, it has an orbital time or 98 years, it will still be close to apoapsis.

6.2) Wers and Vizea, Pol-like twins

Spoiler

After having so much trouble trying to get an assist at Imterril, I decide to go for a straight transfer on Wers.

 

Trajectory from Tannor to Wers, first part

It's only 900 m/s to get the right apoapsis, and going to Imterril would require at least 600 m/s anyway, more for a faster trajectory necessary to leave Tyepolbynar gravity. So, I may at most save 200 m/s; not worth the effort.

I decided to launch immediately instead of waiting the transfer window because of inclination. As you can see in the picture, at this time solar apoapsis would coincide with the planar node, so I will be able to merge capture burn and plane change. This, of course, will require spending a couple orbits around Kaywell. I have 15 years before I have to prepare for the Reander-Fophie transfer, enough time.

Some obligatory scenery porn. Probably the last time we'll see Tyepolbynar

Those tend to get old, but I still prefer to insert some rocket pics every once in a while

Trajectory from Tannor to Wers, second part

Here I'm splitting the capture burn in two, the first is periapsis raising to syncronize the orbital time and get the encounter, the second is the actual capture. I also split the plane change between those two burns. Wers and Vizea are very small, roughly the size of Pol; they have no significant Oberth effect to make capture cheaper.

Arrival. Vizea is the one on the right

Capture burn

Releasing Cigar. With tanks mostly empty, no need for much fuel

Wers. It's quite nice, actually

The sky is also in good shape

More Wers landscape

Wers is actually pretty nice. Gravity is low, but not so low that driving a rover becomes frustrating. Sightseeing is good. I decided to drive around the place.

More sky and sightseeing

Here we have two differently-colored biomes that are both labeled as midlands, and are the same biome. A minor glitch

Final route over the surface of Wers. I explored a bunch of biomes

Only 300 m/s left, will they be enough to reach Vizea? Yes, gravity here is so low

Vizea

Vizea has those deep chasms on the surface. Nice from orbit, but from the surface they are quite underwhelming

Landing, and a very smart question on a science report that somebody should have answerd before the mission

Driving on Vizea

Vizea is slightly smaller than Wers. But it's not interesting. It's mostly flat, even the mountains are not remarkable. I left it quickly.

Once more, it takes very little fuel to move around the twins. Even with Cigar practically dry, I still have enough

6.3) Egad and Yeerbor, the explorables

Spoiler

Boundless still has plenty of fuel, let's head for Egad.

Trajectory for Egad. For once, a straigh Hohmann - though with a sizable plane change. Also, status

I considered using a Valyr gravity assist to make this cheaper, but considering my time constraint of catching the Reander-Fophie transfer, I don't have enough time. While I do have enough fuel to take the direct route.

Ejection burn from Wers and Vizea

Arrival at Egad

Egad is a terrestrial planet. Surface gravity half a g, surface atmosphere 0.78 atmospheres. A good place for aerobraking and flying. Though Boundless needed to lose almost 1 km/s, and to brake this much it still risked destruction.

View during aerobraking

Aerobraking from the rearward cupola, currently enclosed in the cargo bay for protection

After some trial and error to find the right altitude, I parked Boundless on a high orbit. If it will turn out to be oriented the wrong way for leaving, I can always circularize. Arrowhead goes to land.

Arrowhead, during descent, flying over a canyon complex

And another canyon complex

And yet another canyon complex

Egad has some similarities with Duna, being red with polar ice caps and canyons. Compared to Duna, it has a lot more canyons, and the ice caps get a lot closer to the equator.

Landed, with some science report. The goo is particularly pyrotecnic, but it makes me feel guilty about experimenting on it

Since Egad looks so good, and I can fly around at high speed, I decide to explore it in depth. It has four biomes; highlands, midlands, canyons, ice caps. I explore all of them.

More flying over Egad

I initially thought this was Yeerbor, but it turned out to be a floating boulder

Here you can better appreciate the chlorine green of the atmosphere. Also, Gememma

Arriving at the polar caps

Landed on the ice caps

Going back to the equator for orbital ascent, the flight path marked

In this gravity, Arrowhead can fly on propellers up to a pressure of 0.14 atmospheres. I didn't load all the fuel, since orbiting Egad is easier than Kerbin

Having not loaded all the fuel, I had barely enough to reach Boundless in its elliptic orbit

Docking back with Boundless

After exploring Egad, I turn to its moon Yeerbor. It's in an elliptic retrograde orbit, but I should be able to compensate by making an intercept at apoapsis. I send Cigar alone, with full tanks.

Trajectory to Yeerbor. 14 days to arrive, with less than 600 m/s

Yeerbor. Cigar is very close, but still outside the sphere of influence

Once inside the SoI, it becomes a lot more detailed

Yeerbor has a truly tiny SoI, barely 25 km; I've seen smaller, but it's equator has an average altitude of 10 km, so there's only 15 km left to the edge. Low space begins around 6 km, so low space science can only be taken near the poles.

Landed on Yeerbor

Driving on Yeerbor

Yeerbor is tiny, at 22 km equatorial radius - though they become over 30 with the equatorial bulge. But it's quite dense, so the gravity is still comfortable enough - almost - for rovers. And it has some interesting sightseeing, though I only did drive to the nearest crater and then cheated my way in position for the rest. Basically, Yeerbor is interesting, but not interesting enough to circumnavigate. I briefly considered it, and maybe in another time I would have. But I've been quite busy this last month, with chess tournaments, baldur's gate 3, and the end of vacations. I don't have the same free time, and I can't circumnavigate everywhere. Which is also why it took me over a month since the previous update.

The north pole of Yeerbor; it's a mountain with a hole on top. I would like to visit the place

One of the fissures. Not as cool as it looked from orbit

Back to Boundless, comfortably within the fuel and food budget (I assume 30 days worth of food and air for Cigar, I've been away 20 days)

6.4) Rik, glorified asteroid

Spoiler

Now all that's left to complete the grand tour is Fophie, that will require its own special mission, Reander, that as a gas giant with a minable moon will have its own mission, Gememma, that will have its own mission... and Rik.

Rik is a tiny body, basically a large asteroid. It's quite unimportant, and it would be a waste to have a mission specifically for it. On the other hand, those tiny bodies are expensive to reach due to their lack of Oberth effect. Rik is also expensive because it has a relatively large inclination. And Boundless is now down to 3 km/s available. Make it 3.5 accounting for the fuel left in the shuttles. Not enough to orbit the diminutive body and then return somewhere else.

On the other hand, getting an intercept on Rik is not too expensive, and from that solar orbit getting an intercept on Valyr is also not too expensive, fully within the fuel budget. And on Rik I can use Traveler to land without slowing down the mothership. That's what I'm about to do.

Egad-Rik transfer

Making an interplanetary burn from apoapsis is not advised; in theory, I should circularize by aerobraking, and then make a big burn, to take advantage of Oberth effect. However, if I circularized I'd have to spend over 600 m/s just to leave Egad's gravity, making any gain minimal. So either Oberth effect is much smaller than I thought on this planet, or the higher energy of the elliptic orbit compensates for it... anyway, I'm making the escape burn from Egad near apoapsis, and it's surprisingly efficient.

Releasing Traveler. Rik is visible sligthly to the left, between two thermal radiators, but it's very dark

2 km/s intercept would be very steep for Boundless, but Traveler has all the fuel it needs

Capture on Rik

I am of two minds on this glorified asteroid. On one hand, the surface is not really interesting. Gravity is also very low, probably too much for comfort. But it does have a couple of interesting craters on it

The aforementioned couple of interesting craters

Landed. For a world this small, I generally don't bother with Cigar

Yep. You see? Flat featureless plain. I'm about to make a statement about this.

Quote

Law of inverse proportionality of interest: the more a celestial body is beautiful and interesting when seen from orbit, the less it will be interesting on the surface

Examples include Rik, Imterril, Etrograd... and that's it, mostly. So I can consider that law debunked.

Anyway, I wanted to see some more of Rik, including the big equatorial crater, so I took a couple suborbital jumps. Fuel is abundant.

Suborbital jump to reach the crater. Notice the low speed involved.

About to land on the crater

Nice, but nowhere near enough to prolong my stay. Time to rejoin Boundless.

By now the mothership is out of Rik SoI, getting away at 2 km/s, but it's still very close to Traveler when the whole solar orbit is considered. The classic way to get a rendez-vous in this situation is to point straight at the target and fire the engines.

Moving towards Boundless, still inside Rik SoI

Once in solar orbit, cancel the relative velocity between the two vehicles

And then add some speed towards the target. Drifting effects will be small and easy to correct

Traveler reunited with Boundless. Wait, I did remember it less... curved

When I came into physical range, the mothership split in three parts

Not a big deal, I reloaded and it never happened again.

Now I run out of both easy targets and fuel, it's time for a refill.

6.5) Totooa is not a gas pump

Spoiler

As I was engaging the trajectory for Valyr and Oshan, I came to realize that Reander may actually be the best place to reach Fophie. The moon Totooa is a viable refueling place, it could be even better than Oshan. From there, I could go into a high elliptic orbit, all the way to the edge of Reander SoI. There, at apoapsis I could make a plane change cheaply. I could skim the surface of Reander on a polar orbit, and from there make a burn. Take advantage of Oberth effect to gain inclination, exit in a good intercept trajectory for Fophie. I teleported Boundless in place and tested that theory.

Simulated trajectory from Reander-Totooa to Fophie; focus in Reander SoI

800 m/s to the edge of the SoI, then 150 m/s to change plane, and 1800 m/s of burn at periapsis. Less than 3 km/s; the first time I managed with just 2 km/s, but I didn't take a screenshot. I may also be able to use a gravity assist from Lito (Reander's innermost, Tylo-like moon) to help.

Simulated trajectory from Reander-Totooa to Fophie; final trajectory

Ok, not a good fit, but this is just a proof of concept. First, the orbit is retrograde compared to Fophie because I'm still in the wrong time window. Of course, when I will make this same maneuver 15 years in the future it will be on the right side. Then, you can see I couldn't quite match the plane because it took 4 years of orbiting around Reander, and by that time the planet moved around quite a bit. But with the proper timing I could match planes. And then, that target orbit would give me a good intercept on Fophie, just for 3 km/s. Looking at the low orbital speed of Fophie, intercept speed should not be too high, in any case within the capabilities of Traveler if I attempt the same maneuver I used on Rik. Then Boundless could take another gravity assist from Reander to slow down and reach another refueling spot within 50 years.

The trajectory needs polish, but I am sure it's possible. On the other hand, it would not have been possible on Tyepolbynar. As it was much closer to the sun, its SoI was much smaller, so inverting the orbit was much more expensive (see the exploration of Etrograd). And second, as Tyepolbynar was much closer to the sun, getting a high solar apoapsis would also have been a lot more expensive.

So I set a course to Reander.

Trajectory to Reander

I did a straight Hohmann transfer for this. Time is an issue, I must reach Reander several years before it crosses the plane of Fophie, here highlighted as the yellow line. You can see, there's time enough. Unfortunately, I had to raise orbit from apoapsis, making it more expensive, but still within the capacity of Boundless. It only means an extra trip for Ice Cream Cone.

Planned arrival at Totooa

Totooa looks like the perfect target. It's got a very small gravity for an atmospheric planet, almost as low as Mun, so it will be cheap to orbit and easy to aerobrake. It's also got a relatively dense atmosphere. Too dense, actually. Once more, I curse myself for not including some skipper engine on Ice Cream Cone. The wolfhounds will have terrible Isp at sea level. But they should still be able to lift the rocket, and then performance will improve quickly as the atmosphere gets thinner. I may be able to mitigate the atmospheric issue by landing on a mountain, too.

Huh. I just noticed how high the atmosphere is. it's bigger than the moon itself. Well, it will be an extra cost to raise apoapsis that high with ICC, but nothing terrible.

Arrival at Reander and Totooa

Reander being beautiful during a passage of its bigger, innermost moon Lito. Also visible two other smaller moons in the center and left of the image

Aerobraking. Totooa's small gravity makes it perfect for this. I could even leave the cargo bays open

Landing Ice Cream Cone. Parachute descent all right

Ice Cream Cone full and ready to deliver fresh fuel to Boundless. Despite the atmosphere, the wolfhounds are still powerful enough to lift the rocket

But... Ice Cream Cone runs out of fuel before reaching orbit. Before even coming close to getting out of the atmosphere, really

I severely underestimated the atmosphere of Totooa. The problem isn't just that it's 200 km high, no. On the real solar system grand tour, Titan had a 600 km atmosphere, and it wasn't a big problem. No, the main problem is that the atmosphere stays dense even at high altitude. On Titan, atmospheric pressure was over 1 atmospheres at sea level, but it quickly went down to 0.1 at 50 km, and it quickly became negligible. But here, even at 25 km the pressure is still one third of its sea level value. Enough to still hinder the wolfhounds, enough to create high drag.

In a low gravity, dense atmosphere environment the best ascent is straight up, because aerodinamic losses are a lot bigger than gravity losses. Which is what I did. But I run out of fuel soon. If I go too fast, I lose too much to atmospheric drag, and if I go too slow, I lose too much in gravity drag, and there's no way out.

But ok, I still have several options to try. Option 1: dock Arrowhead to Ice Cream Cone. Arrowhead has engines that work in an atmosphere, and it also has extra oxidizer tanks to provide additional deltaV. Part of the problem is ICC having low deltaV due to small oxidizer tanks.

Arrowhead Cream Cone landing, it's quite ridiculous but it works

And here it launches, using the efficient darts to tackle the atmosphere

But the wings have an angle of attack that pushed the ship completely off course

Ok, this can't work. I still haven't tried launching from the top of a mountain. The highest locations I found on the equator are 7-8 km high.

Well, I did make it to 40 km of altitude, already a marked improvement over last time. Still, nowhere near orbit. And notice how at this altitude there's still 0.13 bar of pressure

Better, but not quite there. Next experiment: borrow the engines from Arrowhead and stick them on Ice Cream Cone. Maybe with atmospheric engines the lander will be able to gain elevation without spending a fortune.

The darts stuck under the wolfhounds are a bit silly, but they do work

Made it to 47 km

I also tried to load less fuel, still not working. Maybe with darts, less fuel, and launching from a mountain, then maybe, just maybe it could potentially work; but not without any meaningful payload.

I finally gave up and removed Totooa from the list of possible refueling places. Actually, checking the planetary pack deltaV map, I see it lists 3900 m/s as the deltaV cost to orbit this moon. More than Kerbin, despite the Mun-like gravity. I'm sure it can be done more cheaply, but the point remains that this atmosphere is a formidable obstacle. Unless one happens to have propellers, Arrowhead almost managed to lift the whole contraption on its own and it will breeze Totooa with minimal effort. But Ice Cream Cone will never be able to get up from here. It wouldn't be able to leave Totooa even if I had used better engines.

So I reloaded and went back to the original plan of refueling on Oshan.

6.6) First refueling stop is never forgotten

Spoiler

Going to Valyr is simple, just like going to Reander was. This time I was forced to lower orbit from periapsis, spending a lot of fuel, but Boundless still has over 1 km/s.

Trajectory to Valyr

Intercept on Oshan; you can see intercept speed will be low by how much the orbit curves around the moon

Arrival on Oshan

The time window for the Reander-Fophie trajectory should be around year 55, so I should be on time. Especially because I'm likely to take a high energy transfer for Reander; to leave with a high intercept speed, one has to come in with high intercept speed.

Refueling is just a matter of time. Quite boring. On one hand, a small refueler is good to minimize mass consumption on the mothership, that has to carry the refueler with it. But it also means it will take many repetitive trips to get the fuel.

Actually the best design was A'Twin, where the refueler came down with the ship itself, allowing full refurbishing in one landing, but it could also be detached for reduced mass. Can I do something similar? Can I land Ice Cream Cone with the rest of Boundless stuck on it?

Yes! This way I only need to land once to refuel!

No. Of course not. I cheated Boundless in place to get that silly picture.

But even if, more realistically, I moved the docking port on the bottom of Boundless, to have the rockets of the mothership help those of the lander, and if the ship could land like that and stay upright and not collapse under its own weight.... even then, on the atmospheric planets where refueling is possible, the engines would not be powerful enough to push a fully loaded Boundless upwards.

Nothing new here, just a slow, time consuming operation. On the bright side, I do need to feel that refueling has a cost to avoid it being too cheap and removing fun.

Following a few pictures taken along the way.

Would it be worth to land Cigar there and drive in the canyon?

Final status; Boundless ready to leave again

Now I'm ready to go for Fophie. After all this trouble, I hope it will know it will not be worth it. P.S. Boundless used to be 793 parts, now it's 794. The reason is that after I took the seismometer out of storage (see parts 3.2 and 3.3 for how I got a seismometer there) and stuck it on Traveler for the Rik landing, I decided it was more practical to just leave it there.

Edited 1 hour ago by king of nowhere

[king of nowhere]

Part 7: With the last drops of water

Boundless finally has the right alignments for Fophie. It was a very difficult target, because its high apoapsis means it takes a long time to reach it - while its high inclination makes it too expensive to encounter at periapsis.

Boundless is supposed to have life support for 50 years, and it managed this trip in slightly above 49 years, making it a very close thing.

The various celestial bodies relevant to this chapter

7.1) Everything you wanted to know about a trajectory to Fophie (and much more than you never wanted to know)

Spoiler

I already mentioned in 6.1 some of the difficulties of going to Fophie. To recap, the only practical way to get into a polar solar orbit is to use that distant gas giant for a gravity assist. That, however, is nowhere near enough. I also need a rocket burn at periapsis.

By the laws of gravity assist, Boundless will leave Reander with the same intercept speed it came in. A solar polar orbit entails a huge intercept speed. However, Oberth effect plays in my favor, reducing the deltaV needed to capture with a low Reander periapsis, for every incoming trajectory. But that means that if instead I burn prograde at Reander periapsis, I am mildly increasing my speed relative to Reander, but I'll have a large effect on the outbound trajectory. I used this same principle to get to Shol and Wolda with a burn at Tyepolbynar periapsis. So, that's the general principle: come in for a Reander flyby, add enough speed to get an intercept for Fophie.

Unfortunately, it's not that easy. The issue with this kind of maneuver (which I may dub rocketgravity assist, or assisted gravity assist) is that getting the alignments right is a pain. Additionally, the game is terrible at simulating it. You place your trajectory all right, then you need to make a tweak at periapsis. So you move periapsis, but it will inevitably change the orbital time too; and since maneuver nodes are tied to time, the maneuver you carefully placed at periapsis is now shifted earlier or later. At a time when the orbit curves, so performing the burn one hour sooner or later completely changes its direction. So you can't carefully tweak the trajectory as you do in normal gravity assist. You have to try a combination, and if that does not work, you have to tweak the periapsis blindly.

I have a very long experience doing all sort of missions in this game, and I can safely say that rocketgravity assists are by far the most complex orbital maneuvers that I know.

First attempt for Fophie

Fophie also does its own to complicate things, but the very first enemy is planetary alignment. From Oshan (the moon of Valyr where I'm refueling) to Reander it would take 1000 m/s under ideal conditions, but Boundless needs to intercept the giant planet as it crosses the planar node with the orbit of Fophie; the Valyr-Reander transfer windows are wrong for that, so I have to launch off window and spend an additional 400 m/s.

Then, as the first image shows, I found easily enough without too much trouble a trajectory; 1465 m/s from Oshan to Reander, 88 m/s of plane correction midway, 1675 m/s at Reander periapsis, an additional 107 m/s of plane change because the first assist was not perfect. There we are, I have an intercept for Fophie with less than 3.5 km/s. Too bad Fophie is not there. Boundless would have to make an additional orbit, and it will arrive on Fophie in 42 years. The 3700 m/s burn is to make its orbit similar to Fophie. Of course, I'm not going to do it. But I needed a way to check that the intercept speed on Fophie is within the capacity of Traveler, and that Boundless can change its trajectory and return in the inner system with its fuel budget.

From this I also found a trajectory to reach Tyepolbynar in 49 years, but the game became too uncertain and didn't let me calculate the capture deltaV. I suspect it would have been too expensive for my leftover fuel.

I need to find an intercept with a higher solar apoapsis.

Final trajectory for Fophie

The final trajectory I found ends up spending a lot more at Reander periapsis. It was necessary to get a high solar apoapsis, to meet Fophie closer to where it is now. 30 years, in this case. At Fophie I will send Traveler with Cigar, saving fuel for Boundless. I will need that fuel next, because as soon as the ships are rejoined, Boundless will have to take a steep (2700 m/s) turn inward, to meet Reander in 46 years.

Trajectory after Fophie

Such an abrupt maneuver is made necessary by life support. I established 50 years worth of water supplies. And as I needed Reander to match plane with Fophie, so I will need Reander to realign Boundless orbital plane to the other planets. Reander has a 28 years orbital time; so I will spend 3 years from Valyr to Reander, then take the Reander flyby. After that, Reander will make a full orbit and another half orbit, for a total of 42 years, and it will be right there when Boundless is coming down from Fophie intercept. Once I have a Reander intercept, I will have roughly 4 years and 3 km/s to find a way to someplace I can refuel. It's my only chance; if I miss Reander, I die. If Reander had a slightly higher orbital period, I'd have to invent something else entirely (probably going to Tyepolbynar, but it would be much more expensive).

The Reander flyby

I am not happy with that 2.2 km/s burn at Reander periapsis. Coming back from Fophie, I only needed 1 km/s to get captured by the gas giant, so I am fairly sure there must be a cheaper way to perform that transfer. But I can't find it. The problem is that Reander has such a strong gravity, if I pass close it does not just pull me upward, but it also slings me back towards the sun. I prepared a couple pics to explain that:

What I want to get from Reander flyby

Ideally, I would like to get a retrograde X component - to enter a polar orbit I need to cancel my horizontal speed - and a strong Y component because a polar orbit needs polar speed. I am sending Boundless to pass in front and under Reander, and I can fine tune the position of periapsis to get the right balance of X and Y. I also need to have a high solar apoapsis. But, if I just went for high apoapsis, I'd get a solar apoapsis on the opposite side of Reander. But I want that solar apoapsis to be placed above Reander (from the perspective of the picture), so I need also a strong Z component, pointing outwards, to change shape of the orbit and pull apoapsis closer to where I need it. In fact, if you look back at the trajectory for Fophie, you may notice it's already a compromise, as I would like apoapsis on the intercept or slightly before, and instead I get it slightly after apoapsis.

What I actually get from a close Reander flyby

As I was saying, the problem with Reander gravity is that it's so strong (it's smaller than Tyepolbynar, much less Shol, but still somewhat bigger than Jool) that on a close passage it will turn Boundless trajectory more than 90°. So I will get my X and Y components as I want, but the Z component will be pointing in the wrong direction. And, as you can see in the next image, it's totally not suitable for Fophie.

And the trajectory that would produce (red dotted line)

So, to avoid turning inward too much, I have to keep a relatively high periapsis. Enough to provide the Z component I need, but I also have to supply a longer rocket burn to complete the X and Y components. I tried also using the innermost moon Lito for additional gravity assist, but it didn't work, it's not big enough to make a difference here.

Finally, a few notes for the return trip. Because I'm tight with both time and fuel, I need to ensure I have some way to come back.

Fophie intercept

Fophie intercept is 2250 m/s, being far from the sun. Traveler can do it easily, and it will only cost 20 tons of fuel. No problem there.

Planned trajectory back to Reander

And 2560 m/s after Fophie to get the new Reander intercept. This screenshot is after I performed the first Reander flyby, I have 5 km/s left, so nominally I will have 2.5 km/s; but in truth, I can cannibalize some more fuel from the shuttles, so it's somewhat above 3. More important, here I can confirm that capture at Reander will be 960 m/s. It means I can perform a rocketgravity assist and go almost anywhere. And that's the most I can plan; the game won't allow me to plan an accurate trajectory afterwards, but I will have enough options that I'm sure I will find something.

Before leaving Oshan, I dumped all the oxidizer to increase deltaV. But here I still have lots of oxidizer. I had to reload the game at some point, and it turns out, I reloaded to before dumping the oxidizer. But it will work out fine, Boundless doesn't have all that much oxidizer and I should still have enough fuel.

7.2) Postcards from the journey

Spoiler

With all the heavy orbital mechanics part out of the way, I can dedicate a subchapter just to pictures taken in those 30 years.

Approaching Reander south pole. One rarely gets the chance to see the polar regions of gas giants

Now Lito is also visible. Lito is as big as Tylo, but still too small to give a sizable gravity assist on this trajectory

The burn at periapsis

I've never been into such an inclined solar orbit before. I was hoping to see something cool looking at the north pole of the star, but that's all I get. I can barely tell it's a binary system

This is the highest inclination, 75°. But there's nothing to see

Despite its powerful antennas, Boundless is about to lose contact with home. And it's barely halfway

The sun seen from the farthest point I'm about to reach in this mission. You can barely tell it from the other stars

7.3) Fophie promises nothing, and delivers

Spoiler

After over half an hour of time warping (Boundless is not a kerbalism mothership, but it still lags heavily; and the trip was 26 years), Boundless is getting close to its target. Time to get out Traveler and Cigar.

The solar panels get so little energy, I had to put the probe cores in hybernation to achieve a net positive. Also, look how slow is the solar orbit

Approaching. This shows how tiny is Fophie against its sphere of influence

Actually, such a high periapsis (I forgot the course correction to improve it) had many problems. Once stopped at apoapsis, I could gently float down towards the glorified comet; it would have taken one year. Or I would have had to spend additional propellant to speed it up, and still lose time. So I reloaded; but I didn't have such a good screenshot.

A few science report. They all mention outgassing, which makes sense at periapsis, but not here. Also, notice how for all the trouble I went to get here, those reports are not worth any extra science

It's shaped like... no, I can't think of anything resembling it

The biome map reveals Fophie as another contact binary

Landed. Gravity is negligible, Fophie is only slightly bigger than Gilly. The bug where you see the sky in transparency beneath the land is in full swing

I liked previous contact binaries, and I circumnavigated them. Perhaps I could do the same here?

This... is not the striking vista I came to associate to a contact binary

Yep, unlike Jifgif or Wolda, which are beautiful and nicely shaped, Fophie does not really look like a contact binary except from orbit. And it's all dark, and featureless, kinda ugly. I got away from it. I wouldn't have had the electricity to circumnavigate anyway.

Leaving Fophie, by pointing straight towards Boundless and igniting

Speed equalized, now I need to move closer to the mothership. I spent most of Traveler's remaining fuel to go faster, I wanted to save time

Boundless reunited. Now I have 5 km/s to go back on a refueling spot

7.4) The way back won't come but once. Be steadfast

Spoiler

With the course set for a return to Reander, I have all the time to plan what to do next. Once more, the very high gravity can be a curse as much as a blessing, as it's very easy to get ejected into a retrograde solar orbit, or out of the solar system entirely. I have to pass close enough, and with the right angle, that I can match Boundless orbital plane to the other planets. And I also need to intercept Valyr or Tyepolbynar soon, I have less than 4 years of life support after than flyby.

Found a route to Valyr

This time I was quite lucky, because Valyr was in the right part of the orbit. Boundless can reach it in 3 years, with one year left to land. I can't simulate the capture, too much uncertainty - looks like rocketgravity assists also scramble the game engine, making it unreliable for predicting much farther - but the way I touch the orbit like a Hohmann transfer, it can't be too high.

If Valyr had not been reachable, I would have had to aim for Tyepolbynar. But that giant planet is much closer to the sun, so Boundless would have arrived much faster; I'm not sure I'd have had enough fuel to capture and reach Tannor.

As an alternative hypothesis, I could have gotten captured on Reander for less than 800 m/s, and from there I could reach Totooa.

Alternative scenario: route to Totooa

In the earlier chapter I discovered I could not land on that moon, but that was for refueling purposes. I am pretty sure that if I salvage the engines from Arrowhead and launched Ice Cream Cone with no fuel load, I could go orbital. That has no game benefit, but I could say that the lander got down to restore water supplies - a few tons are enough, unlike the huge amounts of fuel required by Boundless to go anywhere. So I could have refreshed the life support countdown; then I already checked, from Totooa to the edge of Reander SoI is 700 m/s, and from there I can take gravity assists, once taken care of the 50 years time limit going back to Valyr won't be a problem.

But I can go to Valyr directly, I won't need to disassemble my spaceplane.

Getting close enough to simulate, It's only 1100 m/s, leaving Boundless with an additional 1 km/s for safety

Good, I have enough fuel. Oshan is good for aerobraking and would have allowed more fuel saving, but it would have required hitting it at precisely the right orbital time when it's going the same direction as Boundless. It was already hard enough to line up the rocketgravity assist for Valyr - indeed, I could probably save most of the 260 m/s of the periapsis burn if I could better refine the periapsis. Lining that up to hit a moon at a specific time in its orbit is beyond what I want to try. Most maneuvers here are the results of hours spent simulating trajectories. Lag does not help.

Approaching the north pole of Reander this time

Everything went perfectly.

Approaching Valyr, Boundless came close to the moon Manonam

Valyr capture

Finally, orbiting Oshan, ready to refuel

I started at 51:417, so the 50 years time limit was expiring at 101:418. I had less than 300 days left, and less than 10% of the fuel, which is good for another km/s. Fophie was really hard with the self-imposed time limit. I don't expect any other body to be comparable, except Ammenon; that, I expect to be harder.

But enoug musings. Now that I am orbiting a nice planet with low gravity and thin atmosphere, I can get new fuel. Which means more days spent in repetitive drudgery. I could just edit the save file to fill my fuel tanks, the result is the same and nobody would know. But I need refueling to have a cost to feel that I'm earning that fuel. Still, I already said it but I reiterate: I will never again build a large mothership with a small refueler that takes dozens of trips to refill the mothership.

One saving grace is that this time I don't need the tanks completely full. Without orbital transfer to mind, I can go to Reander with 1 km/s. After exploring all its moons, I can reach Gememma in a fast trajectory in 20 years with 1.5 km/s. I can then get captured on Ollym, a place that could be even better than Oshan for refueling. I'd need only 3 km/s, but I want to also try and visit Mandrake, Gememma's gas giant, before refueling. So I'm bringing 5 km/s total.

Refueling done, I have enough

It says 4.5 here, but a bunch of that fuel is locked with no transfer to the main engines, because it's reserved for the landings. And then it will get consummed and make Boundless lighter. I did bring a lot of oxidizer, though, because there are a lot of places that require Arrowhead. I am confident I can visit both Reander and Mandrake in one go, but if that proves impossible, I can always just head straight for Ollym.

I'm getting ahead of myself. Next chapter will feature Reander, and then we'll see.

Edited October 3, 2023 by king of nowhere

[king of nowhere]

Part 8: Reander and the seven moons

Boundless visits the giant planet Reander and its seven moons. Not many difficulties here, but a lot of interesting worlds to explore.

A family portrait of all the moons of Reander

8.1) No, we're not ready to start yet

Spoiler

From Oshan I have a comfortable transfer window to Reander every couple of years, but I can't leave just yet. After Reander I'll go directly to Gememma, a trip that will take a couple decades - in a high energy transfer. I don't expect issues with life support, but I can't be wasteful. And right now Reander is just in front of Gememma, in the worst position for a transfer. I want to send Boundless to the gas giant when it will also find a good alignment to leave for the dwarf star. So I set the time warp on and waited...

... some fifteen years. Reander rotates slowly.

I suppose I could have loaded more fuel on Boundless, launched immediately, and used an higher energy transfer to make the Reander-Gememma trajectory while out of alignment, but I had no particular reason to take the extra effort.

Trajectory to Reander; a straightforward Hohmann transfer

I said earlier that it takes 1000 m/s to go from Oshan to Reander, now it's 1400. That's because Reander has quite the eccentric orbit, I'm approaching it towards apoapsis, need to raise more. Still, fuel consumption is within projected levels. I absolutely have enough to reach Gememma, and I expect I'll also have enough to explore Mandrake - Gememma's gas giant - before needing another refuel.

A mild course correction later, I got an intercept for Totooa. I already talked about this moon with the small gravity and huge atmosphere. While its ludicrous gas envelope frustrated my attempts to land Ice Cream Cone there, the combination is perfect for aerobraking.

Approaching Totooa. It's got some nice geological features

I feel like I still should be in high space, but I'm in atmosphere already. The atmosphere is bigger than the moon!

Entering atmosphere at 1300 m/s. It feels like a waste of Boundless carefully engineered aerobraking features. The only difficulty is not landing accidentally.

A Reander-rise

While Boundless can't get new fuel, Totooa is still the best parking spot available. Aerobraking saves fuel, and it will save fuel for Traveler's inbound trips too. Lito also has an atmosphere, but it's very close to the gas giant, leaving would have been too expensive.

8.2) A tour of the inner moons on the way to Lito

Spoiler

Lito is the only really challenging landing aroud Reander. I did spend quite some time narrating how hard it was to leave Totooa, but that was only because a pure rocket like Ice Cream Cone is not suited for the task. Arrowhead will have a very easy time getting past the atmosphere.

Lito is another matter. It's roughly the size of Tylo. It's significantly easier because it has an atmosphere, but it's a thin one. Nominally it reaches 0.24 atmospheres at sea level, but every section of the planet I visited was at least at 4000 m of altitude, and atmospheric pressure was already halved. So, I can aerobrake, but I can't land Arrowhead - can't fly it at all, too much gravity and too little air. What I can do is loan a couple parachutes from Ice Cream Cone and strap them on Arrowhead, to enable a reasonably cheap landing. Arrowhead will need to conserve fuel to reach again orbit.

Bill takes a spacewalk...

... to grab some parachutes

Then Arrowhead is paired with Traveler. I had included a whole extra large tank for Traveler to carry around Arrowhead, but I actually can't use it. Arrowhead has the issue of spacing with the small shielded docking port, and the extra fuel tank for Traveler would not fit. I am sure I could manage with some EVA construction, but too much of a hassle - and no need. I'd rather save fuel. As it is, Traveler has only 2600 m/s because of the heavy load it's carrying - fully loaded, Arrowhead is well above 40 tons. I could reach Lito directly on this trajectory, but I'd have very little fuel left for the return trip. Better to take the slow route. There are three other moons between Totooa and Lito, all roughly the size of Mun, so they can be used for some gravity assists.

Route to Lito part 1: From Totooa to Dakkon

Just a simple trajectory for now, once on Dakkon I will find the best ways to lower the orbit. I included the data for the moon, showing its escape velocity to be very similar to that of Mun.

Traveler leaves Totooa; Boundless is visible on the left, in the distance

A triple passage of the moons. This spectacular event is actually quite common around Reander. On the lower left Yokane, upper left Lito, to the right Yalthe

Route to Lito part 2: finalizing the first gravity assist

Traveler will follow the yellow Hohmann transfer - with a small adjustment in 6 days - for a first flyby of Dakkon in 12 days (day 156). This first flyby, also aided by a 20 m/s maneuver, will send it on the blue trajectory, which has a 1:1 resonance and will enable a second flyby in 39 days (day 184). This second flyby can insert Traveler in the purple orbit, which appears to be the limit of how much I can lower orbit with just a Dakkon gravity assist. I will have to provide additional thrust.

Approaching Dakkon. It's mostly a smooth snowball

Except for some fissures around the surface. Science reports indicate it may have a liquid ocean inside

Route to Lito part 3: after the second Dakkon flyby

Since a gravity assist from Dakkon alone wasn't enough to reach Yokane, Traveler had to provide an additonal 28 m/s on the flyby of day 184 to further lower orbit along the purple dotted line. By coincidence, Yokane was passing by, enabling an immediate flyby on day 190. Traveler will eject on the blue orbit, which has a 1:1 resonance with Yokane. The 50 m/s maneuver is mostly a plane change.

Another multiple passage of moons in front of Reander

The same, magnified. I am reluctant to include too much scenery, because with seven moons this will be a long chapter. But then, what's the point of a grand tour if you can't gawk around?

Route to Lito, part 4: second Yokane flyby

This image is taken just before the first Yokane flyby of day 190. Traveler will leave on the resonant orbit, which this time is purple, and find a second flyby 10 days later on day 200. It will propel the spacecraft on the blue orbit, which is low enough to meet Yalthe.

Yokane is covered with volcanoes

Yokane has a very interesting geology with some sort of "continents", apparently made of ice, rising above plains that by the color could be rich in sulfur. More of that in Yokane's chapter

Route to Lito, part 5: from Yokane to Yalthe

The Yokane flyby of day 200 was good at lowering orbit, but it left me with a conundrum. Traveler wouldn't be able to meet Yalthe for a very long time, the orbits were almost resonant in a way that would prevent an encounter. Nor could I get a better outcome with a different flyby; those moons are small, they only provide limited assists. And while I'm in no particular hurry, I can't take forever - least Reander moves out of its favorable position for a Gememma transfer.

Ultimately, I found no better way than spending 128 m/s to further lower periapsis and ensure an encounter with Yalthe 57 days latet (day 257).

Route to Lito part 6: first Yalthe flyby

During the first Yalthe flyby, I need an additional 76 m/s to ensure a resonant orbit (dotted purple) that would achieve a 3:1 resonance, for a second flyby in day 270. That will eject on the dotted blue line. This close to the gas giant, maneuvering becomes more expensive, and the gravity assists aren't enough anymore. If I don't want to spend a lot of time chasing long resonances, I have to pay some extra fuel. It's fine, my only objective is to make sure Traveler will have enough to return.

Yalthe is quite flat. It also appears to be a sulfurous volcanic plain with plenty of hotspots

Route to Lito part 7: second and final Yalther flyby

As Traveler approaches Yalthe for the second flyby, on day 270, I decide I milked the gravity assists as much as I reasonably could. Sure, I could chase some kind of long 11:10 resonance to try and lower periapsis a bit more, but it's not worth the effort. To return from Lito I need some 2 km/s, which Traveler will have once Arrowhead uses up its fuel and becomes much lighter. So, shortly after the flyby places Traveler on the purple continuous line, I lower periapsis to encounter Lito. It only takes 218 m/s, a reasonable amount. By now I also lowered apoapsis enough that intercept speed on Lito is 400 m/s. That will translate to a periapsis speed of 2700 m/s, which - both Traveler and Arrowhead being built to handle some heat - should be slow enough to aerobrake safely.

Finally, 150 days after leaving Totooa, Traveler reaches Lito

8.3) Lito: plains, mesas, and a giant ball in the sky

Spoiler

Arrowhead and Traveler are well hardened to aerobrake in those conditions. It's only got one major issue, in that their combination is aerodinamically unstable. The craft just starts flipping around and never stops until you're out of the atmosphere. I suspect it to be a limitation of the physical engine, in reality an object must have some kind of stable configuration. Anyway, a plane with big wings flapping around makes a lot of drag, so the whole ensemble gets decelerated fast and unpredictably. Getting a capture instead of staying in an escape trajectory or falling on the ground was more a matter of luck than anything else.

Traveler + Arrowhead flipping in the atmosphere

Moving towards apoapsis, Lito and Reander seem to be crushing a smaller moon, probably Yokane

Traveler is stabilized in orbit, Arrowhead is dropped on the surface.

Descent

As you can see from the picture, Lito is a world built a bit like a platform game. You have a general plain, rolling but mostly even, and you have some mesas, with flat tops but steep sides. The purple glow of the atmosphere isn't particularly realistic, but it adds a nice touch.

Arrowhead can't flight on propellers here, but it sure can glide a long distance if it comes down from orbit. By the time it landed, it crossed at least a tenth of planetary circumference.

Flying over a mesa, with some science reports

Time to land, I installed the parachutes for this moment

Arrowhead floats gently down, the rockets providing the last bit of braking

But it didn't go well the first time

Nor the second

Nor the tenth

Ok, what's the deal here? Those parachutes are useful for slowing down and getting a controlled descent, but they also limit the capability to steer. With them, Arrowhead must fall with the parachutes pointing straight up. It means it has no way of directing the rockets, or losing residual lateral speed. The end result is that the most likely result is to hit the ground, fall on a side, crash. Or maybe pick up too much lateral speed because Arrowhead is not pointing perfectly straight up, and all that hovering time compounds that.

Ok, if the parachutes create so many problems, do I really need them? Yes, I do. Arrowhead comes down too fast to even try a normal landing. But to make a rocket landing I'd have to turn the plane around - good luck with that - and point the rockets downward. Maybe some ace pilot can do it, I can't for sure. There's also the deltaV issue. Coming down from high speed would require braking for several hundred m/s. I'm not particularly tight on fuel, Arrowhead is made to orbit bigger planets, but I can't be too wasteful either.

No, I need the parachutes. What I could have actually improved was placing them more evenly, so that Arrowhead would fall exactly vertical. I placed them on the upper part, because this way the nose is tipping down slightly. I thought it would increase the odds of the plane falling down on the side of the wheel, instead as on the roof. What I didn't consider was how it would also pick up lateral speed with every ignition - and that speed would compound to the point of making landing impossible.

To fix that, I'd have needed to move the parachutes. But on board I have a scientist and a pilot, the engineer was left aboard Traveler. I don't want to replay the long descent phase, I ca keep going by trial and error.

Indeed, eventually I did manage to find the right mix of thrusting...

... to gently sette down on the ground

On Lito. The mesa in the distance is the same seen a few pictures ago with the science reports

I face, unfortunately, a grave conundrum. Reander is most spectacular in the sky. But the gliding went on too long, it's not visible from here - and of course Lito is tidally locked. I want to take a nice landing picture with the gas giant in the sky. The obvious solution is to drive westward a few hundred kilometers. Yes, I was looking forward to driving around anyway.

ù

Here showing the atmospheric pressure. While Lito has a nominal surface pressure of 24 kPa, on the average surface it's more around 10

IVA view of the setting sun and the vast plains

Sunset without light amplification. At midday there's still decent visibility, but light levels are generally low. We're over twice as far from the sun as Jool

Approaching a long thin mesa, I take the challenge to go over it

Arrowhead can't fly, but its propellers still generate enough thrust to act as effective rover propulsion. Unfortunately, that's nowhere near enough to climb up the steep mesa cliffs, so a lot of switchbacking is needed. The situation gets worse with altitude, and with steeper inclines causing the rover to slide downwards. But I wanted the challenge, so I took my time. The mesa looks deceptively small, but it's over 4 km high above its surroundings.

Switchbacking on the cliffs

The mesa, seen from above. It's oriented almost perfectly north (to the right) to south

I called it piece of sh!t plateau because its long, rounded shape really reminds me of a dog dropping on a sidewalk.

I made it to the top, at over 9 km of altitude. Here the pressure is barely one fifth of the nominal sea level

Then down to the plain on the other side. I have to be careful to not go too fast

A day on Lito only lasts 4 and a half hours, so it's sunrise again

Gememma in the sky. Without diamonds, I'm afraid

Beautiful purple glow. Reminescent of Eve, but slightly darker

And finally, after over 200 km, I crest a hill and find what I came for: Reander visible above the horizon

In greater magnification

With sights like these, I often wonder what it would have done to an ancient civilization to develop in such a place. People living in some places would never see that giant ball in the sky, but they would hear stories. Other civilization would have a giant planet hanging above them all the time. Would they figure out the law of gravitation earlier? Would people from the Reander side think themselves blessed by the presence of their god and genocide the people from the other side? Would they even be able to prosper at all, with the extra shadow?

Here I found a place of particularly low elevation (in 300 km I never found anything below 4000 m) and tried to fly. But lift is still only half of weight

At this altitude Arrowhead would be able to fly if it dumped all its fuel. But it needs that fuel, of course.

Two moons crossing the sky. On the left Yalthe, on the right Dakkon

Magnified as they are about to disappear behind Reander

Also, flying rocks. I should stop being surprised at those

Another moon rises to the east. It's too far to see in detail, but judging by color and apparent size it's probably Yokane

Eventually I stop, after covering 20° of latitude

Each of those flags is 100 km apart, so I run 300 km on Lito in a few hours. Reander is still visible only as a slice, but to view it in full I'd have to cross over a thousand kilometers. I got enough good pictures already. Still, I kept this save. I may want to complete the circumnavigation at a later date.

To ascend, I begin by flying on rocket power

And opt for a low inclination approach, using the wings to generate lift

Probably not the most efficient ascent profile, but adequate

Reuniting with Traveler. I was able to use Arrowhead remaining fuel to raise apoapsis, so I'm already in an elliptic orbit for cheaper departure

Having saved much fuel on the way down, and with Arrowhead much lighter, Traveler now has 2800 m/s. And it takes less than 1 km/s to reach Totooa, no problems

8.4) Totooa, the gas dwarf

Spoiler

After returning to Boundless, I load a smaller amount of fuel - less than half the maximum capacity - and land Arrowhead on Totooa.

Totooa is notable in having an atmosphere almost bigger than itself. 243 km of radius, 201 km of atmosphere.

Even the crew is surprised by how high the atmosphere starts

I'm well inside the atmosphere, but I can still see the whole planet

It's like Totooa is a gas giant, with a huge gas part and a (relatively) tiny rocky core in the middle. A miniature gas giant!

Totooa has a varied surface with mountains and plains. Here are mountains

And here plains

Science report mention tholins and keep the analogies with real life Titan. Also, different texts for surface samples in different biomes, I like that

In natural light. While the sun is still high, there's decent visibility. I still prefer some amplification, though

This biome is named chaos, it has a lot of those smaller irregular mountains

Flying to the next biome; Arrowhead can move fast and the planet is small, so I got all of them

The surface of Totooa includes a large mostly flat lowlands, with vast continent-like highlands of higher elevation but still flats. Some rifts are cutting through that, and in the boundary there is often chaos terrain of varied elevation.

Two moons above the horizon. They are probably Yalthe and Yokane, judging by the colors

Getting a good view of a flag planting. A boulder also got inspired by all those objects in the sky and decided to copy them

At this low elevations, Arrowhead can fly up vertically

Even at 60 km of altitude, with only 5 kPa, Arrowhead flies smoothly

Totooa includes a large mostly flat lowlands, with vast continent-like highlands of higher elevation but still flats. Some rifts are cutting through that, and in the boundary there is often chaos terrain of varied elevation.

70 km, 3.4 kPa. This is how high I could go before using the engines

Returning to orbit was easy, the hard part was clearing a lower atmosphere extending well above 40 km. Even the limited amount of fuel I brought was totally overkill. Orbital speed around Totooa is 400 m/s.

8.5) Mally and the kangaroo race

Spoiler

Next I visit Mally. It's a trojan of Totooa, so reaching it is a matter of slowing down or accelerating orbit. Mally is a smaller moon, little more than an asteroid.

Trajectory to Mally

Some pictures of the spacecrafts involved

Arrival at Mally. I  turned down the light amplification here thinking it would look more "real", but it just looks darker

Mally is just a heavily cratered rock

Orbital speed is so low, I don't even need to brake Cigar, I can just bounce on the surface

Cigar bounced and flew away several km. I wanted to plant a flag here, so I sent out Gilmundo. Then I chased the rover with the jetpack, like I did during the previous circumnavigations

Here the second bounce, Cigar still flew away while the scientist planted the flag. I'm rotating scientists for every landing, by the way

Finally Cigar stops 20 km away from its first touchdown. It seems Mally's only remakable feature is its redness. Also, I feel very bad for what is being done to the poor goo

Those 20 km of bouncing race are a significant part of Mally's circumference. This moonlet is only slightly bigger than Gilly

Return to Boundless. Not much point showing the return trip, trajectories are trivial

Just wanted to show this unconventional IVA view. I downloaded a whole mod to get more varied crew pods, I only included this one, but I didn't show it

8.6) Yawer, miniature Mesbin

Spoiler

Now Cigar goes to Yawer, the outermost moon. Travel times are fairly long. DeltaV costs are fairly small.

Route to Yawer

When I classified all the planets at the beginning of this mission, Yawer barely made it past the 300 m/s of escape speed required to qualify as Mun-sized. Still, this is a body requiring a few hundred m/s to orbit, so I have to load some fuel in Cigar. I also know it rotates fast and has a dark emisphere.

Wait, what's that oblate in the distance? I thought I left Mesbin for good

Yaweer rotates fast, making it oblate. In fact, it does look a lot like a smaller version of Mesbin. That equatorial bulge stops just short of geostationary orbit; orbiting a few kilometers above the surface, you can see the surface below moving faster than your ship. It does create the curious feeling of orbiting retrograde.

Yaweer also has cool geographical features

Showcasing the rotational difference in two pictures taken at close intervals - see the time stamp and orbital data. Orbital speed is 215 m/s, but only 18 m/s relative to the surface

I could have skipped loading that fuel, after all.

This is definitely a cool place, I want to drive around.

About to land on the heavily cratered equatorial ridge

With a few science reports mostly remarking on the unusual shape and rotation

Biomes on the surface are a mess, just driving a few kilometers I can collect a bunch of them. I landed on the bright emisphere, I decided to go drive all the way to the dark spot. Gravity is low, but still comfortable for driving. Though I am going against the rotation of the planet; if I was moving eastward, I may accidentally accelerate to orbit.

Bunch of driving among the craters

Unfortunately, as I was driving towards my target biome, I suddenly noticed Cigar was missing the docking port. I don't know how I could destroy it without realizing, but I had to reload back almost half an hour. That killed my driving mood, so I went back to orbit. But again I kept the save, this is another world where I may want to run an Elcano eventually.

I also used alt-f12 to check the dark emisphere, I wanted to see if there were some interesting reports.

No, I can't really tell the difference with any other dark terrain by night

Return from Yaweer

I decided to spend some extra deltaV to return faster. I already spent 300 days around Reander, I'm getting somewhat concerned that I may lose the optimal transfer window to Gememma. Traveler doesn't consume much anyway, especially half empty like this.

8.7) Yalthe, land of volcanic plains

Spoiler

Yalthe is the innermost moon except for Lito, but still cheap to reach. I left Traveler mostly empty. I would like to make a single trip to all the remaining three moons, but they are all fairly big, Cigar does not hold enough fuel to perform more than one landing, and I have no way to store extra oxidizer.

Route to Yalthe

More nice moons

Yalthe, in all its splendor

Those black spots turn out to be volcanic calderas. They seem a nice place to land

Yalthe has cool science reports

Yeah, yeah, don't get close to the lava. Nice touch of realism there. So, I see there is another biome just in the middle of the caldera, I wonder what it will be?

While there was a caldera on the equator, the one with the different biome was not. Had to drive 20 km to get there

Inside the caldera

HEY, I FOUND THE OTHER BIOME! AND IT'S MELTING MY ROVER!

Wow, that was amazing. They had a volcanic world, and they made an actual lava biome, and they set its temperature to actually be lava-like! Congrats to the devs. Too bad for my rover exploding.

Moving around, I discovered the location of the hot spots does not match that of the lava biome exactly, so that there are some places where it's lava biome but it's still survivable. Hence I got science data for lava.

Best! Science reports! EVER!

Aside from that, there's no particular interest to this planet. It's flat and featureless except for the calderas.

Ok, I got what I came for, and more. Time to leave

8.8) Yokane, the one with cliffs

Spoiler

Yokane orbits very close to Yalthe. I doubt they could be stable in real life, too much gravitational interference.

Route to Yokane

Yokane has a striking contrast of "continents" of ice and "oceans" of sulfur

One of the few celestial bodies to have something akin to terrestrial plate tectonics. It also has volcanoic hotspots

A view of Yokane. Landing zone is in that small white "island" just north of the calderas in the middle of the image

Exclusive to Yokane are those near-vertical cliffs. They are everwhere near the boundaries of the continents

It would be interesting to get a geologist there to theorize about their formation. They do not look like fault lines

I landed on a sort of hill, or very small continental plate. Science reports focus on the surface being constantly quaking

It does beg the question, though. If Yalthe and Yokane are so active because of tidal heating, what of Lito? It's a lot closer to Reander, but it's quiet.

I drive a bit to the tip of the "island". There are basically three terrain types here: lowlands, highlands, and volcanoes

Reaching one of those cliffs. Here it forms a closed circle, almost like a crater or a caldera

Then south, to the caldera

Those lowlands are very flat, while the highlands are a lot more irregular, even before considering the cliffs

To the edge of the caldera

There is lava here too. Again, with a bit of searching I got to a place that wasn't too hot and I could get science

Then it's again time to move on. Yokane is beautiful, but running a full circumnavigation here would become boring. It would be interesting to develop a system to deal with the cliffs, though

One last view of the cliffs and landscape before moving on

8.9) Dakkon, cracked snowball

Spoiler

Finally Dakkon. It's the closer target to Totooa, and I left it for last.

Planetary alignment is unfavorable right now, but it would take some 50 days to get a transfer window. I'm still concerned over my transfer to Gememma, so I sacrifice a few hundred m/s of deltaV on Traveler - equivalent to only a few m/s on Boundless - to save that time with what I call the cochlea maneuver.

Route to Dakkon

The cochlea maneuver consists in aiming for a lower periapsis to catch up with your target, followed by a maneuver at periapsis to lower apoapsis and reach the target in an approximation of a Hohmann transfer - this way intercept deltaV is still low. It's only marginally more expensive than a real Hohmann transfer, and much cheaper than any other option with this alignment.

Dakkon is a smooth ice ball with some cracks here and there. It also has exactly two biomes: highlands, and lowlands - which are the rifts

Passing over one such rift

Here I wanted to showcase how the smooth plain give way suddenly to a wide canyon, but the image doesn't really work

I made sure to land in the middle of a major rift. Looks more interesting

Landed on a steep slope, there's nothing but steel slopes in this rift. And look, the goo managed to survive and escape! Go, goo! Our hearts are with you!

I start driving. I want to get out of the chasm to the highlands biome

By the way, if you're wondering how I'm driving in the darkness with a solar-powered rover - or even more generally how I'm driving this far from Kaywell where the solar panels are giving me 0.05 EC/s in the best conditions - I admit I'm cheating infinite electricity to drive. Those solar panels are barely able to maintain the basic probe functionality otherwise. I wanted a mission with solar panels mostly for aesthetics, but this far from the sun - and with Gememma non providing any electricity - it would be impossible to use Cigar otherwise.

I want to stress, though, that the infinite electricity cheat is only used for driving - which is a completely superfluous activity as far as the grand tour is concerned. Bounless has enough solar panels and batteries to be self-sufficient even now, and even at Gememma. Plus it gets extra power from the RTGs on Arrowhead. And Traveler has enough battery to last through maneuvers, and will slowly recharge in the sun.

This is probably the most irregular terrain I've ever seen. A lot more complex than even Wal

Some more driving on this terrain

Took me a couple hours to cross 15 km as the bird flies. Of course birds don't fly in the vacuum, so I'll have to stick with driving the rover

What looked like the final crest before the plateau was just another set of peaks

I flew Raberta on the peak to take this picture

Cigar can drive, but it's not a sturdy rover. It's made to be light. I'm curious as to how a rover built for survivability, like Dancing Porcupine or Leaping Mantis, would handle this terrain.

Wait, now that I think of it, this isn't really any worse than the polar regions of some planets. Trying Dancing Porcupine here would be a miserable experience, just like it was on Polta. On the plus side, it would not explode all the time like Cigar is doing. I've been saving the game every couple of minutes to cross this terrain. And I am pretty sure Leaping Mantis would handle itself fine.

As Cigar moves towards the highlands, the land becomes more regular

Until a few kilometers later it's almost completely flat

Taking samples from the highlands, then back to Totooa

This completes Reander. None of the moons was particularly challenging, only Lito was somewhat difficult. However, there were seven moons, and I did spend some time on each one of them, so it still took some time. By the end, I was quite exhausted and couldn't wait to leave. As a testament to how long this stretch of the mission was, it took me two days to write this chapter.

This completes all the Kaywell-Limnell system. The only targets left are the ones orbiting Gememma, 10 landings in total. All of them should be easy, except Ammenon, the most difficult of all. Time for a status of what's left on boundless

Status of Boundless after the exploration of Reander, with already a planned maneuver for Gememma

My concerns were overly alarmistic, I'm still well within a good transfer window where I can reach Gememma with less than 1 km/s and less than 20 years. This will leave 2 km/s on Boundless, so I should have enough fuel to explore Mandrake - Gememma's gas giant - before having to refuel. But I'll leave that for the next chapter.

Edited November 26, 2023 by king of nowhere

[king of nowhere]

Part 9: A tale of giants and dwarfs

Boundless enters the Gememma system and explores the moons of binary gas giants Mandrake and Rutherford and the dwarf planet Pragnik.

Left, the positions of Mandrake and Pragnik around Gememma; Gannovar highlighted to showcase how tiny is the inner Gememma system in comparison

Right, the moons of Mandrake. Rutherford is a gas giant roughly the size of Sarnus, all the moons are bigger than Minmus but smaller than Mun

9.1) Welcome to Gememma!

Spoiler

I closed the last chapter with a status also showing a planned route to Gememma. I ended up using that. It's not a clean Hohmann transfer, because I needed to stay within the 50 years life support limit. But between the distance from the sun and Oberth effect from Reander, I'm not spending much more. Gememma has a huge sphere of influence, the only difficulty was lining up the encounter with Mandrake.

The planned route to Gememma

Goodbye Totooa

And the planned insertion on Mandrake

Boundless will not arrive on Mandrake at the ideal time for a capture. The problem is, Mandrake takes a couple years to orbit, and the timing of my arrival was such that it was in the wrong part of the orbit... no, ok, if I had wanted to tweak the Gememma arrival to get to Mandrake half a year later, I could have done it - though the maneuver involved a complex tridimensional burn and would have required some fiddling.

The reason I didn't worry about coming to Mandrake on a high energy trajectory is that Mandrake has a twin gas giant, Rutherford, that can be used for a gravity capture. Indeed, it's what I'm doing here. Not clear from the picture, but Boundless is coming in from a high inclination (could not be avoided, the orbit of Gememma is inclined and Boundless did not pass through the planar node during the trip from Reander); it will make a pass over the north pole of Rutherford to mostly clear that inclination, and get captured with a high apoapsis.

While Rutherford seem extremely convenient for gravity assists, it actually is not. It's very close to Mandrake, meaning that while you can capture there, your resulting orbit will have a low periapsis, and Mandrake is also bigger than Jool (really, must every gas giant in this mod be bigger than Jool?). This will make capture on a moon much more expensive. Indeed, for a low energy transfer it's cheaper to skip the gravity assist entirely and go for a direct capture on a moon, despite those moons being too tiny to help much with Oberth effect.

My chosen trajectory reflects that issue. If the main problem is raising periapsis, I get Boundless captured by Mandrake with a high apoapsis, so that it will be cheaper to raise periapsis. Also, on such a high orbit it will also be cheaper to refine the inclination, I could not get exactly zero with the gravity assist. So, after the gravity capture a 440 m/s burn at apoapsis raises periapsis to the level of Tatian, the outer moon, making this a Hohmann transfer to the moon. Capture deltaV will be low, the 160 m/s figure includes circularization. 30 m/s is the final plane change, I could not get a perfect zero inclination from the Rutherford flyby alone.

I picked Tatian because, being the outer and slightly bigger moon, it's Oberth effect would help both with capture and departure from it. But in practice I could have chosen any of the other moons, they are all close and similar.

A final note, I initially was hoping I could send Arrowhead in atmospheric flight on Rutherford, because I saw its gravity was lower than 1 g. But as soon as I gave a more accurate look, it clearly was impossible, it takes too much deltaV. Rutherford is much smaller than the other gas giants in this mod, but it's still Sarnus-sized; the original Arrowhead could fly in Urlum and Neidon, but those ice giants are a lot smaller than that. Seeing that, before leaving Totooa I dumped most of the remaining oxidizer, which was being saved for that purpose.

In Gememma sphere of influence

Besides the science reports, I have to comment on solar panels. I was expecting Gememma to not produce electricity, much like Limnel, but the devs clearly tried to model its light - and got it bugged. As you can see in that image, the solar panels are producing a lot of electricity, as if Boundless was at this distance from Kaywell. Indeed, the solar panels are pointed at Kaywell, not at Gememma, despite Kaywell being too weak to produce significant electricity at this distance (I commented on electricity shortages around Reander, and Gememma is two to three times more distant). On  the other hand, when Kaywell is covered by a planet, the light of Gememma does produce some electricity - probably the one intended by the modders, because it's a lot weaker than Kaywell, as a red dwarf should be.

Finally, with all 7 main antennas deployed - the four main RA100 relay ones on Boundless, and the non-relay communotrons on Traveler and the two Redentor probes - Boundless manages to catch a signal from Mesbin, at least when planetary alignments are right. It depends on how close Gememma is to periapsis and where exactly are Mesbin and Mandrake. Not that it matters, but it's nice that my massive overengineering is good for something. I suppose people are expected to build up a relay network to communicate with Gememma normally.

First sightings of Mandrake (deep blue) and Rutherford (light blue). In the red circle is also a moon, barely visible, probably Tatian

9.2) Boundless in the sky with gas giants and moons

Spoiler

With the trajectory already set, all I have to do is enjoy the spectacle in the sky and try not to take too many screenshots.

Approaching Rutherford, with science reports

Periapsis near the north pole. Wow!

And a close up of the pole. I would like to fly a plane there. Then again, my experiences flying planes in gas giants were kinda underwhelming

Periapsis on Mandrake

A close view of Mandrake. If you look closely to the right, you can also see Tatian as a handful of pixels

You won't be able to see a double passage of moons anywhere else. Tatian is passing in front of Rutherford, while Jancy is passing in front of Mandrake

A close-up of Jancy, and underneath is Beagrid. Beagrid is not much smaller than Jancy, but it's a lot further

Getting closer to Tatian

An interesting little world. And here I was thinking just because this place is remote it won't have anything of value

By coincidence, the capture burn on Tatian includes the gas giants in the rear view. The big bright spot is Kaywell; I thought the small one was a moon, but it's really a sky artifact - Beagrid is close, but not visible without zooming

9.3) Rally racing on Tatian

Spoiler

Dropping Cigar on Tatian

Tatian has a varied and complex geology

As shown by its biome map

As I've been moving farther from Mesbin, most moons keep getting simpler, with less biomes. Not in this case. Since the place is interesting, I decide to take a long trip over it to get multiple biomes. You can see in the picture the landing spot on the yellow crater biome, and I want to reach the purple spot.

The landing area

Climbing out of the crater, with some reports. Surface sample reports vary with biomes, nice!

Out of the crater, the land becomes more red. Likely it is covered by tholins, while the impact dug out the underlaying ice. Must have been a very young crater on a geological timescale

Tatian is middle sized between Mun and Minmus. The rover takes frequent jumps, but the reaction wheels keep it upright. The terrain is smooth enough to not present special problems. All in all, an easy drive.

A pretty good science report, written by someone with good understanding of planetary science

In natural light. This far from both stars it's just too dark for comfort

One of the many rifts. They look much better from orbit

Finally, the purple spot was a mountain. Not an impressive one, though

I did drive some 150 km on Tatian

9.4) Lozon and Jancy, not quite interesting enough

Spoiler

The remaining three moons are small, a single fuel load on Cigar will be enough to land everywhere. DeltaV for transfers are also small, since they are all orbiting close together. On the downside, since they orbit at similar speeds it takes forever for a transfer window; but I'm not in any particular hurry, I still have over 30 years worth of life support.

Tatian to Jancy with 200 m/s. I only loaded Traveler to a fourth of its fuel capacity, and it still feels overkill

Jancy. It also looks interesting, but I would not write poetry to it

Landed in a crater

And driving upwards

On top of that hill, and down the canyon to the right

This way, I got four different biomes while driving less than 10 km

Jancy looks pretty, but not enough to stay longer. Next I move to Lozon, for the only reason that it was the transfer window that came up first. I could spend more fuel to go faster, but again, I'm not in any hurry.

Jancy to Lozon, also with 200 m/s

Approaching Lozon, to the right of the picture

That... looks very different from anything I've ever seen, except perhaps OPM Priax

This terrain really does not look like anything I've seen, not even Priax

Looks more chaotic than even the rifts on Dakkon

I am curious to drive on it

Lozon is the smallest of the moons of Mandrake, and the gravity starts to be felt, making driving uncomfortable. The terrain is smooth in places, up close the real chaos is only limited to a few spots. But those spots... they are crazy.

Here passing over one, but thanks to the low gravity I'm just jumping over

But this time I'm falling through

"Landed". Navigating this terrain could be a nice challenge for a rover. Except in the low gravity it's not really difficult, just slow

Gilmundo fell while trying to plant a flag. He fell on the rover, too

I was about to wait a transfer window for Beagrid, when I just noticed something that made me reconsider all the "no hurry" policy: a transfer window to Pragnik.

The position of Pragnik relative to Mandrake

Pragnik is in a very inclined orbit. I could go there with Boundless, fine enough, but it would be expensive, I don't want to have one more refueling sequence just for a dwarf planet. I could go there with Traveler, it's got enough deltaV, the problem is the flight time, I decided one year and unlike the Etrograd mission this time I won't handwave it. The only way to make the trip in a short time is to launch when Mandrake and Pragnik are passing close to each other, so I was lazily looking for such a transfer window eventually... it's just that I wasn't expecting for that transfer window to come right now! This is an emergency!

Now I regret taking my time on the moons. I could have explored all three and returned comfortably on Tatian in time for just a few more tons of fuel. But I don't want to reload, not after driving around so much. But the clock is ticking and Lozon is perhaps in the worst possible position to reach Tatian quickly. On the other hand, the eight tons of fuel I loaded in Traveler translate to a couple km/s, let's see the fastest trajectory I can get with that...

High energy return to Tatian, spending most of the remaining deltaV

I wasted a few tons of fuel, but that's still pocket change for Boundless, it won't make a difference.

https://i.imgur.com/ifGONTe.png

I'm not sure why I did transfer the crew with a spacewalk, but I realize I never took a picture from this perspective

9.5) Remote Pragnik

Spoiler

To explain why I have to rush for this opportunity, let me show the orbital positions of Pragnik and Mandrake.

Orbits of Pragnik and Mandrake. In red the planned outbound trajectory, in green the return to Mandrake

Pragnik has a very inclined orbit slightly outwards that of Mandrake. It is possible to take a slightly outward trajectory from Mandrake and intercept Pragnik as it's crossing Mandrake's orbital plane. The inclination is paid with the intercept deltaV. On a short stay, I could also leave Pragnik the same way, paying the inclination while I eject, and return to Mandrake in an approximation of a Hohmann orbit. The costs should be well within Traveler's fuel budget. Time limit is also factored in; Mandrake's orbit lasts two years, the planned trajectory takes somewhat less than half an orbit of Mandrake.

The problem is that I need Pragnik to pass in the planar node just as Mandrake is arriving, so that I can launch Traveler with that timing. And this is why having this opportunity was worth dropping all I was doing and taking some uncomfortable measures.

The actual trajectory

Unfortunately, since I need to leave Mandrake while I'm too close for a proper Hohmann trajectory I have to take an expensive trajectory moving outward from Mandrake instead of prograde. Also, I have to add some inclination, since the passage on the node is not perfectly timed. I'm spending 3.7 km/s for this, which is, fittingly, half my deltaV. A bit more, but capture on Mandrake will be less expensive. Also note how Cigar is only carrying a smidgen of oxidizer, but still all its liquid fuel, to provide some extra for Traveler.

Leaving Tatian

I do believe somebody got inspiration from Pluto for those science reports

Well, by the biome map this is another interesting world. What is that striped region?

Wow! Looks like some giant scratched the planet

I'm definitely going to land there

And we have a winner for the planet/not planet argument!

Driving around a bit

Pragnik has a slightly lower gravity than Minmus, making it uncomfortable to drive on it - though it is significantly bigger, giving it a higher escape velocity of 303 m/s, just barely higher than the 300 m/s I arbitrarily set as the limit to categorize a world in grey or green in the map on the first chapter. This is now the first place in my list of potential circumnavigation, but I may want a better rover for it. And right now, every other interesting place on this planet is far away from my position, so I'm not staying.

Another interesting spot, a plain made of convective cells. Yup, definitely taken from Pluto

Goodbye Pragnik, I want to return some day

Return trajectory. I am leaving Pragnik going practically north

The same trajectory, seen from a different perspective to better understand the positions of the planets

It takes a bit over 2 km/s to pay the plane change, and I'm doing it in two rounds; first when leaving Pragnik I lower inclination, and then I cancel it completely when passing on the node. Arrival on Mandrake is on a near perfect Hohmann, only 80 m/s for capture. It's also fast, arriving in day 170; I left on day 277 of the previous year, it will leave me 107 days to return to Tatian.

Incidentally, I want to take this chance to visit Mandrake's low space and its upper atmosphere.

Mandrake's upper atmosphere. The planet can rival Neidon for beauty from afar, but from up close it's kinda underwhelming. No interesting science reports either

Return to Tatian is not possible within the current time and fuel budget. Here the best attempt would use all the fuel, but would take 50 days too long

Unfortunately, I mentioned the worst problem when capturing in low orbit of a gas giant is the intercept deltaV on the moons. Traveler only has 700 m/s left, which are barely enough. I already established in this case the cheapest trajectory is to get captured with a high apoapsis, and raise periapsis from there, as it's cheaper to raise periapsis from a high apoapsis. But high apoapsis means a long orbit. The image shows the best I could do, using up all the fuel - planned burns for 630 m/s out of a budget of 710 - and it would return on Tatain 154 days after arrival at Mandrake. Which is 47 days more than one year. But using a lower apoapsis to make a shorter orbit is too expensive.

So I had to reload and give up on the atmospheric dip. In this case I found out it was cheaper to go for direct capture on Tatian; whatever I lose on Oberth effect is more than made up by not having to pay to raise periapsis.

The final return trajectory. Well within the fuel budget

Once more, I become aware of how convenient the gravity assist on Jool is. In all the mods I've seen, I've never seen any other planet where gravity capture worked so smoothly. It's almost like somebody designed it to be a good training ground for gravity assists....

Just a random picture of Cigar docking unconventionally

Ice Cream Cone blocks the direct path to dock. To avoid it, Cigar can maneuver with the RCS system. Or, if one does not want to wait, it's possible to just use time warp; in time warp the game does not check for collisions, so Cigar will just pass through Ice Cream Cone. Carefulness is necessary to stop time warp after Cigar exited Ice Cream Cone, but before it enters Boundless.

9.6) Beagrid, the waxy ocean

Spoiler

The last moon to visit is Beagrid, then I can move to the inner Gememma system.

Normal transfer to Beagrid. Traveler has only loaded 10% of its fuel

Beagrid passing in front of Mandrake, showing its one feature over what would otherwise be a formless surface

Those transfers are so cheap, Cigar alone has more than enough fuel to reach Beagrid, land, return. The problem is time. Cigar has life support for one month, the trip to Beagrid can be accomplished in 12 days, but then Beagrid and Tatian will be in a horrible position for the return trip, that cannot be accomplished in 18 days. Not without spending much more deltaV than Cigar has. But before realizing this, I did try to send Cigar alone, and in the process I took the only good picture of Beagrid in its entirety. Which is why the next pic will not show Traveler.

Beagrid is entirely covered by the "cellular plain" that was also present on part of Pragnik, and that's basically a form of cryovolcanism

Besides the large mountain that could be appreciated in the transit over Mandrake, Beagrid also has smaller hills. Likely icebergs of water ice floating over the denser nitrogen ice underneath

Beagrid is very smooth, from orbit. But the surface is actually pretty irregular, even if there are no big changes in elevation

Those icebergs are kinda small when seen up close

Wow, that's crazy. Wait, on second thought that exactly how our world works too, with continents floating over the denser lava below. So nothing out of the ordinary

I'm liking Beagrid, and I am curious about its geology. So I decide to go visit the mountain; it's to the north, one to two hours by rover.

The no ground contact bug strikes again; the wheels sink in the ground and have no traction

The trip was largely uneventful, save for the no ground contact bug. It's been occasionally present on many small bodies, but on Beagrid it struck extra hard. At some point I just gave up on using the wheels, cheated infinite fuel and for propulsion from the rocket, because the bug was everywhere and made driving impossible. I did remember to deactivate the cheat before returning to orbit.

The rift between two convective cells. I need to find some synonim of underwhelming, because I've been using that word way too often to describe such features

After a couple hours, the mountain reveal itself in the distance. It's basically recognizable as such

Adding insult to injury, when I got over it I discovered it's the same biome as the icebergs - they are supposed to be different, they get different colors, but it's another glitch that sometimes happens in this mod. So I didn't even get any additional science report. That was the cherry on top of the cake of no ground contact bug; I was considering a circumnavigation, but now I left Beagrid as soon as possible.

Docking back to Traveler. The mountain is called Bickorabne mons

And just a cool docking pic

And this concludes the outer Gememma system. Normally I would also include the trip to the nearest refueling station and the refueling in the report, but I discovered that for Lowel/Ollym, my next targets, intercept speed is 5 km/s (ejection is cheap with a Rutherford gravity assist instead). Boundless also has 2 km/s, I will have to take some gravity assists, and I'd rather break the chapter here.

Edited November 26, 2023 by king of nowhere

[MythicalHeFF]

On 10/23/2023 at 7:56 PM, king of nowhere said:

 

  Hide contents

 

HEY, I FOUND THE OTHER BIOME! AND IT'S MELTING MY ROVER!

Wow, that was amazing. They had a volcanic world, and they made an actual lava biome, and they set its temperature to actually be lava-like! Congrats to the devs. Too bad for my rover exploding.

Moving around, I discovered the location of the hot spots does not match that of the lava biome exactly, so that there are some places where it's lava biome but it's still survivable. Hence I got science data for lava.

Best! Science reports! EVER!

Aside from that, there's no particular interest to this planet. It's flat and featureless except for the calderas.

 

 

That is actually insane that Gregrox managed to modify the temperature of the Lava biome on Yalthe/Yokane to melt your rovers, I had no idea that this was even a thing when I was doing my grand tour last year. When I went to Yalthe myself, I thought it was the most boring place in the whole Reander system.. guess I should have inspected it more closely! 

Also, I don't remember seeing any of those "fault lines" on Yokane when I was there... that's certainly an interesting terrain feature... same with Dakkon and Totooa! I might have to go back and do a more comprehensive mission to Reander and its moons some day; ever since my grand tour attempt failed due to endless game crashes, I've sort of stopped playing this mod.

[king of nowhere]

1 hour ago, MythicalHeFF said:

That is actually insane that Gregrox managed to modify the temperature of the Lava biome on Yalthe/Yokane to melt your rovers, I had no idea that this was even a thing when I was doing my grand tour last year. When I went to Yalthe myself, I thought it was the most boring place in the whole Reander system.. guess I should have inspected it more closely! 

Also, I don't remember seeing any of those "fault lines" on Yokane when I was there... that's certainly an interesting terrain feature... same with Dakkon and Totooa! I might have to go back and do a more comprehensive mission to Reander and its moons some day; ever since my grand tour attempt failed due to endless game crashes, I've sort of stopped playing this mod.

never had crashes myself, so far.  though I did have conflict with other mods, but alone it worked perfectly

[king of nowhere]

Part 10: Air, water and fire

After a lenghty inward trip, Boundless reaches the inner Gememma system, exploring twin planets Lowel and Ollym, minor world Gallant, and Gannovar.

The various bodies in the inner Gememma system

10.1) Inching inwards

Spoiler

My original flight plan for this part involved at this point going from the Mandrake-Rutherford system to the inner Gememma system using a gravity assist from Rutherford, and aerobrake in one of the inner worlds - three of them have atmospheres, and they are all fairly small.

The trajectory to exit the Mandrake-Rutherford system, using a Rutherford gravity assist

Goodbye Tatian, eye-shaped moon

And goodbye twin blue giants

I was assuming deltaV would not be an issue; without a gravity assist, it takes 2 km/s from Mandrake to lower periapsis to Lowel, so I was expecting I'd have 2 km/s intercept speed - low enough to aerobrake in those small gravity worlds, especially as I'd still have some fuel left. Well, I probably have too many achievements to say I am an idiot, but I certainly can still make idiotic mistakes, for all my experience. Yes, it takes 2 km/s from Mandrake to Lowel, so intercept speed on Lowel will be 2 km/s. Just in the same way that it takes 280 m/s from Mun to reach a low Kerbin periapsis, so once in low Kerbin periapsis it will take only 280 m/s to circularize orbit, right? No, anyone who landed on Mun knows it's 850 m/s on periapsis. It takes a lot less deltaV to lower periapsis from high orbit than it takes to circularize afterwards.

And so I discovered I had over 5 km/s of intercept speed. That's way above what Boundless can aerobrake.

I can still make it; Gannovar is nicely positioned to provide gravity assists and lower my orbit to reach Lowel with lower speed. Though Gannovar is only mildly larger than Duna, so it does not provide a big push, it will take a lot of flybys to lower orbit enough. Then again, the alternative is to just return to Oshan, again. Refueling is a slow, boring process, I'd rather skip it.

In retrospect, I wonder if it would have been the faster option after all.

Let's start with the Gannovar flybys

As you can see from the cyan trajectory, representing trajectory after the flyby, Gannovar does not make a big difference. 100 m/s worth of apoapsis lowering, sometimes a bit more. It will require dozens of passages.

And this is Gannovar! Quite beautiful, isn't it? The reddish hue is natural light, courtesy of orbiting a red dwarf star

The bluish hue is the light of Kaywell, while Gememma is under the horizon. The rocket burn is a correction maneuver to refine next apoapsis

It took two years for that first orbit, but I'm on track for another Gannovar flyby

In an infinite time, I could get to Lowel for almost no cost. Unfortunately, I have limited food supplies. I left Oshan the last time in year 116, which means I have to resupply again before year 166. Twenty years are not a lot if I have to perform dozens of gravity assists. I am counting on the orbits becoming gradually shorter, saving time. This means that instead of using the gravity assist to get the cheapest next flyby, I spend some fuel every time to ensure a shorter trajectory.

To achieve the most from every flyby, I try to skim the upper atmosphere. Doesn't go very well at 7 km/s

The aftermath of one aerobraking attempt (yes, I made several. I wanted to test exactly how deep I could go in the atmosphere. Roughly 1 km, it turns out)

It's funny how those engines are still flying in perfect formation after the fuel tank to which they were attached got blown up

The first orbits were easy, because orbital times were long. Gannovar has a orbital time of 28.6 days, so I could always find another flyby with a minimal change of apoapsis. As I got lower, I started having to choose between spending additional fuel to make my orbit shorter, or passing farther from Gannovar to keep the next orbit longer. As long as the cost of shortening was in the tens of m/s, I went for this route. I was concerned about making it for the year 166 deadline.

Boundless using only two rockets, for maximum finesse

For greater savings - and because the game was sucking at calculating close approaches, making them disappear at times - I started planning in greater advance, trying to get ejected already in a resonant orbit without need for course correction. This required very precise maneuvers, sometimes as little as 0.001 m/s. To perform them, I created a new command to shut all engines on Boundless except two.

What happened to the propellers? There are fans all around the place

Unfortunately, I am out of free action groups. I had to overlap with some other command, and I picked the one that seemed most innocuous. My bad, it was the command to lock the propellers on Arrowhead. Propellers have a bug that will bend them out of shape if they are used in a vacuum. To prevent that, I deactivate the rotors as soon as I leave an atmosphere. Guess what, I accidentally reactivated them. I only noticed this a long time later, as you can see from the game time - it's year 154, while I left Beagrid on year 142. At this point I decided I'd just replace Arrowhead.

Action groups are set as such:

1: Activate/deactivate reaction wheels on Cigar. Open/close science cargo bay on Arrowhead. Deploy drills on Ice Cream Cone

2: Open/close propellers cargo bays and activate/deactivate rotors on Arrowhead. Activate drills on Ice Cream Cone

3: Run all science experiments on Cigar and Arrowhead

4: Deploy/retract antennas and solar panels, on all subships

5: Activate engines on all ships except Traveler

6: Activate engines on Traveler

7: Extend/retract the robotic parts that pull solar panels on Boundless inside or outside their cargo bays

8: Open/close solar panels cargo bay and engine nose cones on Boundless

9: Shut down all engines on all subships

0: Deploy/retract solar panels and thermal radiators on Boundless. Retract solar panels and antennas on every other ship

Too many things to do for too little action group keys. Too much lazyness to find and install a mod to get more action keys. But so far it worked. 0, 7 and 8 are pressed in sequence to put Boundless in aerobraking mode; after accidentally breaking some antennas accidentally left open, I added the retract antenna command to 0 too. 9 shuts down all engines on the shuttles, to make sure only the main ones on Boundless are working. And when I deploy one, I activate its engines with 5. When I have a lander coupled with Traveler I can activate only the engines of Traveler by pressing 9 and 6 in sequence. And now that I'm writing this, I realize I could have easily put the activate/deactivate main engines on Boundless on 9 too; it's a key that won't mess up anything if I press it. Also on 4, it would have just opened some antennas in space, nothing bad would have happened. Instead, I fixed the issue by changing the command on Arrowhead to flat deactivate rotors. This way I can't activate the rotors with an action command, I have to activate them manually, it's only two of them anyway.

After seven years, apoapsis was brought down from 11 Gm to 5 GM

It's worth noting that while this represents more than half the amount I have to lower it, since it's going to become more expensive as I move closer to Gememma, I'm still not eve close to half the required number of flybys. On the plus side, orbital time has now shortened to 170 days, allowing multiple gravity assists in one year. I am pretty confident I can make it in 16 additional years at this point, provided I don't dally.

Two consecutive planned flybys

Do notice the 30 m/s maneuver at periapsis to shorten the orbit and make it to the next encounter; the alternative would have been to stay farther from Gannovar and aim at the next encounter, 28 days later. Notice also the Gememma apoapsis being lowered at each passage. This part feels endless, but bit by bit I am moving downwards.

As the orbits kept getting even faster, I could no longer get orbital times that were multiples of Gannovar orbit. I could no longer make sure to encounter Gannovar at the next passage. So I brought out my old datasheet to calculate resonances.

Like this

Current orbit of 50 days, in 200 days Gannovar will have completed 7 orbits. I will exit with an orbital time of 45.7 days, allowing for another encounter in 228 days. It's year 153 now, it still takes time to run so many gravity assists.

The final resonance

As the orbital time of Boundless matches that of Gannovar, it's more and more complicated to find resonances. But I don't have to keep this up forever; I only need to lower Gememma periapsis enough to intersect Lowel. I could have easily intersected Lowel when leaving Mandrake, but I'd be coming down from an 11 Gm apoapsis; using Gannovar, I lowered apoapsis to 2 Gm, allowing a softer intercept.

I could have instead used Lowel to lower Gememma apoapsis, and then I could have occasionally used Gannovar to raise periapsis. It would probably have been more efficient, but a bit harder to do. Planning a resonant orbit is easier than changing your target every time, especially when there is an inclination difference between them. Damn, I have a clear mental picture of what I mean, but I have no idea if my explanations are understandable by some reader. Not that I should worry, because I doubt anyone actually reads this.

Anyway, it's now time to change target and go for Lowel. This requires a significant plane change.

The last Gannovar flyby

This last flyby will match Boundless periapsis with Lowel, allowing a Hohmann trajectory. Lowel has an orbital time of 7 days, encounters will be plentyful. I will beat the deadline by 9 years.

On the other hand, do notice my shrinking fuel budget, from 1600 m/s just out of Mandrake to 1100 right now, 100 of which will be spent for the plane change. While all those maneuvers were small, there were dozens of them, and they do add up.

This felt like it took forever, but judging by the time, and by how much each flyby shortened the orbit, I probably used, like, 15 gravity assists or so from Gannovar. The 21 consecutive flybys I used to reach Io in the real solar system grand tour are most likely still my longest chain of flybys. And likely to keep the record, this is way past the point where it gets repetitive.

The last flyby of Gannovar, taken to minimize the plane change cost, offered an unprecedented view of the polar regions. If only there was something to see there

10.2) Running on fumes

Spoiler

I already knew, from having run previous simulations, that even after lowering apoapsis with Gannovar I'm still too fast to aerobrake immediately. Even if I spend the remaining fuel to slow down first.

Arriving at Lowel. Still 3050 m/s intercept speed. Adding the 2450 m/s of escape speed, I'd hit atmosphere at over 5 km/s

I lost roughly 3 km/s thanks to Gannovar, but I still need to lose another couple before I can get captured.

My first plan was to use Gannovar's moon - or twin, depending on definitions. Ollym rotates around Gannovar every seven hours, and it is much smaller, roughly Vall-sized. Unfortunately, there are a few issues with that. First, I'm still too fast even for an Ollym capture. But it's ok, I planned to use Ollym flybys to slow down relative to Lowel.

More problematic, I can't use Ollym for gravity assists without spending a lot of fuel in correction maneuvers. We all got used to targeting the moons of Jool, but Jool is slow; a maneuver to arrive a couple days later, when Tylo is in the right position, only requires a few m/s. But in this case, Lowel rotates very fast around Gememma. So if I want to arrive and find the right alignment with Ollym, I need to arrive, say, three hours later, in that time Lowel already moved significantly in its orbit. Which means that I won't get away with a small course correction, I would need to change Boundless orbit entirely.

Finally, Ollym has a very thin atmosphere, like Tannor. Which means, I can't really get captured here, not unless I'm already going very slow.

Instead I'm taking a gravity assist to keep lowering Gememma apoapsis

So, I am optim for plan B. Wait, maybe plan A was to aerobrake at Ollym, B was to use Ollym for gravity assists, so this is now plan C? Or maybe original plan was to aerobrake directly from Mandrake to Lowel and I'm now at plan D? Well, regardless. YetAdditionalContingencyPlan is to use Lowel to lower Gememma periapsis. Ok, but my speed relative to Lowel will stay the same. And for a long while I believed that there was no way to reduce intercept cost without using a third body for gravity assists. However, several months ago some other poster (maybe I'll look up who it was and post some thanks) told me that yes, you can reduce your intercept speed just with two bodies. In this case I have to use Lowel to lower my orbit, then burn at apoapsis to raise the periapsis and get again into a Hohmann transfer. This will reduce intercept speed on the planet by more than the amount I spent to raise periapsis.

I've been aware of this option for the best part of an year, but I've never had a chance to try it out. My penchant for kerbalism means time is important, and this kind of strategy requires multiple resonant flybys on a planet. Here for the first time I have a planet rotating fast enough that I can perform this maneuver in reasonable time, while also having low enough fuel that I need to try this. I have no idea how much I can effectively save. This approach still requires spending considerable fuel to raise periapsis, and I'm down to 950 m/s left. I can only hope it will be enough, or I'll have to reload back a couple weeks of real life gaming time.

Wow, Lowel looks super interesting!

Emerging from the planet's shadow, I also see Ollym, Lowel's twin. Actually I took this picture much later, but the actual "first sighting of Ollym" picture is kinda ugly

Trying to aerocapture at Ollym. I just told you I'm still too fast, but back then, I still didn't knew it

Indeed, though I spent all the fuel to slow down, Boundless is still too fast to brake hard. And if it does not get captured, it will crash on Lowel next

So, I aim for more Lowel flybys

5 km/s is slow enough that I can take shallow atmospheric dips. Oxygen atmosphere, straight channels... what the hell happened on this planet?

By the way, this is how Gememma looks from a cupola. The dot slightly under its center is Ammenon. This is the first time in this game I can see a planet while orbiting another planet

60 m/s to raise periapsis. Let's see how much I lowered intercept speed with that. I'm not sure why I also spent 66 m/s at periapsis just to ensure a faster flyby; time is no longer an issue, fuel is

Impact with atmosphere now at 4200 m/s! I lowered my intercept speed by 800 m/s by spending 200 m/s total! I had no idea this maneuver was that effective

But I'm still too fast, let's do it again.

This time 28 m/s to raise periapsis. Again, I'm not sure why I'm spending 42 m/s at periapsis instead of changing flyby earlier. Probably I just thought I could afford it?

Wait, now that I think about it, Ollym was never in the right position to use for gravity assists, but it was often in the right position for Boundless to crash into. Maybe I'm just tuning the time to avoid Ollym? But why not change the flyby trajectory instead of making a course correction later? Maybe because the game does not let you see the trajectory that far in advance? Not sure. 40 m/s would be unremarkable normally, but right now it's 7% of my total deltaV budget.

And intercept speed lowered by another 270 m/s

For the next flyby, for once Ollym is aligned right to take a gravity assist from it. It will slow Boundless some more

Do notice that just because Lowel has an orbital period of seven days, this section is still not fast. In the above picture, it takes 58 days before crossing the red twins again, a 3:8 resonance. The thing is, I have very little control over my orbit. This deep into a gravity field, even slight changes in trajectory cost a fortune. Maybe that's why I need to spend one tenth of my deltaV at every course correction.

Intercept speed lowered to 3600 m/s, which is low enough to spend some significant time in the atmosphere and brake some significant speed

The red color given by Gememma, the atmosphere, and Ollym, all make for an incredible sight. Why there is a green shade next to the water? Could it be vegetation?

Finally, this time it takes 150 m/s to raise periapsis, but afterwards capture speed is as little as 700 m/s. This time I can get captured

I have 500 m/s left, and I'll need to spend 150 of those immediately, but afterwards I'll only need aerobraking and small course corrections.

At 2.8 km/s, I can finally go for a full capture

Lowel is so beautiful when aerobraking over it

Now that I'm captured, a small course correction will send me in an Ollym aerocapture trajectory

Aerobraking at Ollym, looking outward from the cupola. Notice the thin atmosphere

Finally in a stable orbit around Ollym. I had 300 m/s left

Safe with 37 tons of fuel, out of a tank capacity of 1870 tons. Took me almost three weeks of real life to get here, which is why there was so much delay between two updates.

10.3) Fixing the damn plane - and everything else

Spoiler

First order of business is to get some fuel, because I don't even have enough to operate Arrowhead. Ice Cream Cone goes for the landing.

A nice visual of the descent from the cupola on Ice Cream Cone

As I'm doing this, I realize I accidentally entered a retrograde orbit on Ollym. Which really hurts refueling operations, because Ollym rotates fast, at 100 m/s, which I gain if I orbit in the right direction. But it's not a big deal, I reload from before Ollym insertion and go the other way. I didn't have much fuel, but certainly enough for this.

An important discovery I made to increase efficiency on refueling is that Ollym atmosphere is so thin, I can keep the solar panels deployed during descent. This slows Ice Cream Cone enough that it can open the parachutes, and I need then to provide only 200 m/s by rockets.

Using the solar panels to aerobrake

And then the parachutes. I considered ICC engines to be massively overkill, but hre their high thrust allows waiting the last second to open them, maximizing parachute efficiency. They are still overkill

I run a handful of resupply missions immediately, to get enough fuel for the various landings, and the main bulk of refueling in the end. But for practicality, I'm going to just save all the details on refueling to their own subchapter.

Just a great view of Ice Cream Cone rendez-vous with Boundless with Ollym in background

Now it's time to get a new Arrowhead, since the old one got its propellers scrambled.  It's a bug, so I'm allowed to bring in a new one with the cheat menu. I don't expect any particular difficulty.

But when I undocked Arrowhead, Traveler's fuel tank exploded immediately

What happened? While Arrowhead is part of Boundless, its propeller blades are ignoring same vehicle clipping. But the moment I undoc k, they become a whirring cloud of fast moving objects. They slam into nearby fuel tanks, making them explode. it's basically a circular saw. Oh, and they do that because the propellers are still rotating. Despite shutting down the rotors, locking them, and activating the brakes. I suppose they are so out of shape that they rotate powered by microclipping alone. Except they should not have clipping as long as they remain part of Boundless. Well, I suppose their fast rotation is part of the bug. Regardless, I need to find a way to detach Arrowhead without breaking anything. My first attempt is to send and engineer in EVA construction to manually remove all those propeller blades. How do I plan to catch those blades that move too fast to be tracked? Simply by clicking at random, they are zipping around all the time, occasionally I'd just click on one. I detach a half dozen blades this way, before accepting that it will take too long to get all of them.

So I come up with a better plan: I have some struts in storage in case of need, and for a long time I thought I was carrying dead weight. But now I can put them to good use.

Using the struts to block the rotors

With this strategy I could stop the blades from doing damage, and safely detach Arrowhead. Some of the propellers exploded, but they did not damage Boundless.

One detached rotor. Do notice the propeller blades; they still count as attached to the rotor, and are still spinning

Ok, now I just have to teleport in a new plane. And I just found this amazing point to snap pictures

But wait, where are all the solar panels?

From what I could ascertain, using the rendez-vous function of the cheat menu can cause damage to robotic parts in the destination ship. In this case, it disappeared all the robotic hinges that were holding the solar panels. Or maybe they just got moved who knows where, because the game is telling me Boundless still has the same number of parts. Anyway, I solved the problem by teleporting the new Arrowhead close, but outside of physical range, and entering physical range normally.

10.4) A cradle of life

Spoiler

I'll start the landings with Lowel, since it looks most interesting. I send Arrowhead alone, it should have enough fuel to make the full trip without needing Traveler.

Just getting out of Ollym sphere of influence is enough to fall on Lowel

Arrowhead looking good while thrusting

Those canals are a real mystery

Arrowhead looking good while aerobraking

About to land. A bit too fast

Arrowhead looking less good after crashing

Lowel has a decent atmosphere, but not enough for Arrowhead to fly. It would be relatively easy to build a plane that can fly here, but Arrowhead is made heavy by its rocket parts. I tried to get a controlled landing - there's just enough lift that I felt maybe I could do it - but in the end I gave up, reloaded, and picked up some parachutes.

Arrowhead landing in a less dignified fashion. But it works

Landed, with a bunch of science report. Confirmed pluricellular life, full vegetation. I wonder what color would plants actually be around a red star

Too bad the game is not equipped to actually show vegetation. You barely even notice a slightly greener hue on certain areas.

Lowel biome map

The place is interesting, and there is enough air to move on the ground. The biome map is very complicated, but it just means I can explore most of them without having to cross the whole planet.

Driving on Lowel

Going down a canal, you can see it's somewhat greener on the bottom

The white dot in the sky is Gannnovar. Those planets are close enough that you can see them for each other surface, something that normally does not happen

More reports, mostly from water biomes. Wait, microplastics?

There's microplastics on Lowel? So, there was some advanced civilization that built the plastics, built the canals, then disappeared without leaving other traces?

Well, I've covered most biomes, time to leave.

With rockets, Arrowhead can go up

Not a ton of fuel left, but enough to go on Ollym

10.5) The land of volcanoes

Spoiler

Now let's land on Ollym. Ok, not strictly needed for the grand tour because I already landed with Ice Cream Cone, but I want to land with some science instruments. 90% of what I do in this grand tour is not strictly needed.

Arrowhead feels a bit oversized for this landing, and the propellers would be virtually useless to move on the ground. Cigar would be more appropriate; I use an engineer to move the atmospheric spectrovariometer from Arrowhead to Cigar so I'll be able to get atmospheric science.

Cigar about to land, keeping a profile to maximize drag

Drag is a problem, in that there's very little and I still need to spend a lot of fuel. Enough fuel that I'll need to climb a high mountain to be able to launch to orbit again. Good thing I wanted to climb a mountain anyway.

Landed, on the slopes of Helios Mons

IVA view while driving

Gravity is comfortably high, and the ground is flat, I feel comfortable pushing for some speed. In over 100 km I didn't crash once; it's probably a record.

From the slopes of Helios Mons I will go to the tip of Zeus Mons. For a sense of scale, it's 70 km from the rover to the first flag

The ground contact bug struck, but time warping fixed it

Going up Zeus Mons. It does not feel like going up a mountain. There's barely any slope, and the top is behind the horizon. It's likely inspired to Mons Olympus on Mars

The rover is somewhere in the middle of the screen, 27 km from the flag in the bottom, but still very far from the top

To the top! It was a lot of road, but it was also fast

10 km altitude

Now launching

Fuel is a big issue, Ollym is bigger than anything Cigar was meant for. The first few times I tried I didn't make it to orbit. You can see I'm using the RCS to squeeze some additional m/s out of the rover. And before activating the engine I gained as much speed as possible with the wheels.

Still going up, still using RCS. Drag is low, but over several minutes it adds up

Made it, with 17 m/s left. Those 30 m/s I got with the wheels made the difference. Also the RCS

10.6) Not just another glorified asteroid

Spoiler

So far I've never mentioned G1 Gallant, except in the introduction. It's a minor world, of no importance. But I still need to plant a flag on it.

A route to Gallant. First part, 2700 m/s for an intercept

And 3 km/s for capture

I considered using gravity assists to get there, but I'm using Traveler here, I can't make it in one year for the round trip. So I strapped on the heavy configuration tank, that achieves almost 11 km/s, which should be enough here.

The ejection had a significant normal component, and was very long

To make up for the long burn, I periodically deleted the old maneuver and made a new one, more accurate to the new position of the spaceship

Gallant. It's not a tiny rock, but it's not a real world either

Biome map on Gallant. There's only highlands, midlands, lowlands. One side of the planetoid is a giant crater, but it doesn't have its own biome

Landed. The science report says it all

Unfortunately, the gravity is just high enough that I can't point Traveler up with the reaction wheels. Fortunately, sliding on the ground works

The return trip. 2400 m/s, leaving 2500 m/s for capture

Capture is more expensive that the remaining fuel, but I don't have to rocket burn the whole intercept deltaV, I only need to slow enough to aerobrake

Ollym and Lowel lined up

Aerobraking. After spending most of its remaining deltaV, Traveler is sturdy enough to survive at 3 km/s

I always love that red glow on water

Returned to Boundless, with 130 m/s. I could have saved a bit if needed, but not much more

In the worst case I could have sent Boundless, but it would have required many more refueling trips.

10.7) Where ice meet fire

Spoiler

Finally it's Gannovar's turn. I'm looking forward to it; not only it looks almost as interesting as Lowel, but it's also the one world with an atmosphere thick enough to actually fly Arrowhead.

I need to move the docking port to dock the cumbersome shielded small docking port. Then I equalized thrust with center of mass by reducing power to the engine on the opposite side

Docking Arrowhead with heavy configuration Traveler

Route to Gannovar

I raise Gememma apoapsis a bit to become more similar to Gannovar orbit, using Hobert effect from Lowel and Ollym. Then I need 700 m/s to lower periapsis, so that it will touch Gannovar in a Hohmann transfer, and 200 m/s of plane change. It will result in 1370 m/s intercept deltaV, which I will mostly or completely aerobrake.

However, it seems the game engine has issues with planets in elliptic orbit, because Traveler kept being misplaced.

Here it's coming in with a 52 km periapsis

But one hour later, when it actually entered Gannovar, it had a completely different periapsis

Actually, it's not a general problem with the game engine, because while I was taking gravity assists with Boundless I had no such issues. Still, I could not find a fix here, except trial and error.

In Gannovar orbit, releasing Arrowhead

Descent. I'm not sure Arrowhead can take off from water, so I aim for the ice pack

Landing close to a minor body of water, separate from the equatorial belt

About to land. Landing on Gannovar ice is difficult because the ground lacks depth perception, you really can't tell how far you are. On the other hand, dense atmosphere and low gravity helps

And now landing on the brackish water. And yes, Arrowhead can lift off from water in those gravity and atmosphere conditions

Looking out from the window

More reports from the hotspots, the largest areas of water

Then it's fly up to take science on the deep pack ice

Away from water. There are those weird artifact lines on the ground, I suppose it's a visual glitch

On one of the few mountains peeking out from the ice

Arrowhead traveled some considerable distance

I even considered circumnavigating the planet in flight, but there's really nothing to see outside of the equator, and the lack of perspective is very disorienting.

Now it flies up as high as it can to save fuel

Arrowhead keeps flying with 17 kPa of pressure. Lowel had 20% more gravity and 20% less atmosphere, Arrowhead didn't miss too much to be able to fly there. I wonder, if instead of Arrowhead I had brought Not! Albatross, from the Jool 5 science mission, would it have flown? It was a better flyer, but it was definitely worse at reaching orbit. But I could have used it, I think.

Nice light show as Arrowhead goes up in the atmosphere

Meeting back with Traveler

To return, Traveler is pointing in the wrong way, so I devise a way to leave Gannovar in a resonant orbit and return pointing in the correct direction

But once more I get twarted by the sphere of influence bug. It's 255-5:07, and Traveler is supposedly entering Gannovar

It's 2 hours later, and Traveler is still supposedly just about to enter Gannovar

So in the end I just brute forced the whole trajectory

I mean, if the orbital calculations are bugged, the screenshot does not show it properly but Traveler still has 5 km/s of deltaV. Enough to return to Ollym easily.

And this is the last time Arrowhead will fly. Unless I make more kerbalism grand tours in the future.

10.8) Preparing for Ammenon

Spoiler

I refueled intermittently, a few flights here and there, with most of them after the last landing. As usual, it was a long and boring process, and I really wish I could go back in time and slap myself when I was planning the mission. Sure, I need some refueling limitation because being able to refuel on any minor rock is too easy, but I should have done a better job than that.

As I anticipated, I was able to deploy the parachutes. Really surprising, because they should not have opened, they are supposed to only open at 0.01 atm of pressure and Ollym has less than that. Not complaining, it was helpful.

Ollym turned out to be a great place for refueling, better than Oshan. The planetary rotation helps reduce cost, and the atmosphere is so thin, there are hardly any losses.

Here I fumbled a landing. Somehow Ice Cream Cone landed on a solar panel and didn't break it. I was able to mine and fly back like that

Flying up. Look at the total drag (12 kN) despite the high speed and low altitude, the atmosphere is really not an issue

Ice Cream Cone can bring up 105 tons of fuel at every trip. I learned to vent some oxidizer before launching, I don't need it right now

More nice pics

And that's all. Next target, Ammenon, is the most difficult. I need all the fuel I can load. And just enough oxidizer to work Cigar, plus land Ice Cream Cone back when I'll return to Ollym.

Status after refueling

The screen on the left claims 7.8 km/s of deltaV, but that's counting the fuel in all subships as dead weight. Traveler's fuel will be spent, while the fuel in Ice Cream Cone and Arrowhead will be used by Boundless, so it's actually significantly more deltaV. Maybe 10 km/s or a bit less. But the real question is how much of that cost I can reduce with gravity assists.

And how long it will take.

On one hand, I'm thrilled. That's the thoughest challenge in this grand tour, a chance to test myself to the limit. On the other, I already had enough of gravity assists when going down from Mandrake to Lowel, I don't know if I want to spend more weeks running dozens of flybys.

Edited December 24, 2023 by king of nowhere

[DennisB]

12 hours ago, king of nowhere said:

Damn, I have a clear mental picture of what I mean, but I have no idea if my explanations are understandable by some reader. Not that I should worry, because I doubt anyone actually reads this.

I understand it. And I read your mission reports. I've read all the major ones of the last 3 years (Grand Tour, Jool 5, Caveman), even I'm just since March in the forum. It's always interesting to see, what is possible, an which effort is necessary to reach it. After I've got a vessel working, I come often back to your missions to see, how your vessels with similar capabilities looked like, to compare the design, mass and performance.

[king of nowhere]

I haven't updated in a month, so I want to give a quick update.

it took me a couple weeks to gather the courage to start. I was worried I wouldn't be able to reach Ammenon, and being defeated after spending nine months on this mission was a daunting prospect. even in the most positive scenario, I'd still be looking forward to a slow slog of dozens of gravity assists - it took 29, actually.
I safely landed on Ammenon a couple days ago, and I found it a lot more interesting than I was expecting, so I'm now circumnavigating it. I want to stop the next chapter of the mission report when I rejoin Boundless, so I can't write it until I finish the circumnavigation in the first place. So, it will take some more weeks.

there is also the issue of the forum being bugged; editing posts may malfunction, and since I write my reports by gradually editing the post (at first I would just write the post in one go, then I accidentally closed the browser and thus lost several hours of work) I am not sure I can even keep making posts.

so, all this to say that it will take a few weeks to a month for the next chapter.

Edited January 23 by king of nowhere

[king of nowhere]

Part 11: The most inaccessible planet

Boundless has to stretch to achieve the 30 km/s necessary to reach Ammenon, the last planet left.

The fuel cost to reach Ammenon is staggering. 5 km/s to lower periapsis, followed by 10 km/s to circularize. And the same amount must be spent on the way back

11.1) Blue planet, red planet

Spoiler

I'm not 100% sure I can reach Ammenon without staging, but there is only one available strategy: first use Lowel and Gannovar gravity assists to reduce periapsis. Afterwards, I may be able to get some kick out of Ammenon itself, but I doubt it; it's smaller than Mun with a tiny sphere of influence. I will have to provide those 20 km/s with fuel. I took that into account when designing the ship: Boundless has 10 km/s, and Traveler has another 10, so if I burn 5 km/s inward, then detach Traveler, then rejoin Boundless on the way out, I should have - roughly - enough fuel. Cigar itself has almost 2 km/s, much more than needed for the actual landing; I expect I may have to finish capture with the lander alone, though that would introduce more complications.

But for now, my goal is to lower periapsis while spending 1 km/s.

Ideally, I would be able to bounce between Lowel and Gannovar, using each other's gravity assists to achieve speed. My issue right now is that a gravity assist does not change my speed relative to a planet; I must leave Lowel at 5 km/s to reach Ammenon, and I need help from another celestial body to achieve that speed. Either that, or I need to spend some fuel to skew my intercept and increase its cost, in a maneuver opposite what I did in 10.2. It was the first time I used that kind of strategy, and it was a lot more efficient than I expected, but will it be enough to achieve 5 km/s of periapsis lowering with jut 1 km/s of fuel?

Trajectory 1: from Ollym to Gannovar

To begin, I eject from Ollym with the least possible amount of fuel to reach Gannovar - it conveniently crosses Lowel's orbit, only requiring a mild plane change and some patience. My intercept on Gannovar will not be in Hohmann conditions - Boundless will cross the orbit. This will entail a higher intercept speed, and with gravity assists I can turn that high intercept speed into a lower solar periapsis.

You can see from the purple dotted line that the resulting orbit will be lower. However, apoapsis will be closer to Gannovar orbit, making the intercept more similar to a Hohmann transfer. That's unavoidable. My intercept speed with Gannovar must stay the same. Right now I have a similar orbit, with an unfavorable approach geometry to cause a high speed. As my orbit will become more different than Gannovar's, approach geometry will improve to keep the intercept speed equal. Eventually I will reach a Hohmann-like intercept, and I won't be able to lower periapsis any further.

Fuel costs this close to Gememma are high, and neither Gannovar nor Lowel are big enough to provide large assists. For this reason, I'm not trying to achieve resonant orbits. My control over my trajectory is too small, and I want to maximize the gain at every flyby. Instead, I am looking at future orbits to see when random chance will bring me close to Gannovar again; then a moderate course correction at periapsis will fix orbital time and provide an encounter.

Trajectory 2: multiple Gannovar flybys. The one in the picture will be the 4th

As shown in the picture above, coming out of the third flyby looking for the 4th. I set the yellow and purple maneuver nodes, both at 0 m/s. Then I click repeatedly "next orbit" on the purple node, going farther and farther in the future looking for close approaches. Eventually Boundless and Gannovar will pass close to each other - those orbits are pretty fast, after all - and then I make a prograde burn on the yellow node to turn the close approach into a flyby. The maneuver on the yellow node has to be prograde because it will raise apoapsis above Gannovar's orbit, increasing intercept speed and allowing to gain more from gravity assists.

Each orbit entails a little gain. Here I'm losing 30000 km of periapsis, but the closer I'll get to Gememma, the more expensive it will be to lower orbit, and individual flybys will be less effective - well, they will be just as effective in deltaV terms, but it will result in a lower periapsis change.

Two flybys compared

As can be seen from the images of the second and fourth gravity assists, this strategy allows to use the correction maneuver deltaV - which I'd have to spend anyway - to increase intercept speed. In this case, I gained 210 m/s of intercept speed while only burning less than 100 m/s worth of fuel.

Inclination may become a problem. In the past, I would often need expensive plane changes. Indeed, dealing with inclination is the only part of orbital mechanics that I feel I haven't fully mastered. A mission like this, where I'm forced to stretch, is a great learning opportunity, and I improved over the previous chapter. In 10.1 I occasionally had to make expensive plane corrections; here I learned to make small corrections away from Gannovar (and later Lowel). The idea is to pass slightly above or below the center of the planet during the flyby, thus adding a normal component to the gravity assist. If properly tuned, this lets me fix inclination - and it often costs less than 1 m/s. In those pictures I have a slight inclination because I hadn't mastered the technique yet.

Bit by bit, I used Gannovar to lower periapsis. Until, after 10 flybys, I couldn't do it anymore.

Trajectory 3: planning the 10th Gannovar gravity assist, targeting Lowel

As you can see, my orbit is now perfectly Hohmann compared to Ganovar. I can't lower periapsis any further. Sure, I can start pushing up apoapsis, but I will have to pay for that. The maneuver of pushing up apoapsis to increase intercept speed and convert it to lower periapsis is more efficient if I am in a more elliptical orbit, so I'll go as far as possible before resorting to it. And you can notice, while Boundless is perfectly touching the orbit of Gannovar, it's still higher than Lowel. So at this point I switch celestial body. Lowel is also somewhat bigger than Gannovar, allowing for stronger effects.

The fuel counter is not accurate; not only I have excluded the fuel tanks on all the shuttles from being used, but the total amount in the orange box is trying to also account for other engines. Running some calculations with the rocket equation, I spent 600 m/s so far. A bit more than I was hoping for, but half of it was just to leave Ollym. I can calculate the periapsis lowering as equivalent to 3500 m/s, with with 3250 m/s still to go; that is, if I plot a burn at apoapsis, it takes 3500 m/s prograde to circularize at Lowel's orbit, and 3250 m/s retrograde to lower periapsis to Ammenon. The sum is greater than 5000 m/s because I'm not getting any Oberth effect from Lowel, but it's useful to estimate how far I have to go - I'm roughly halfway, not bad. But so far, I managed mostly to take advantage of having a large speed relative to Gannovar. With Lowel I will need to build up intercept speed.

Last Gannovar flyby. I gained another km/s of intercept speed. I am passing significantly away from the equator to change plane for Lowel

11.2) Half a million km in nine years

Spoiler

Now that I'm back to using Lowel, flybys are more effective, as can be seen by the greatest amount of periapsis lowering compared to the last Gannovar flyby.

Trajectory 4: from Gannovar to the first Lowel flyby

First flyby of Lowel (I put a number on all the pictures for easier counting afterwards) at 4800 m/s

Trajectory 5: from first to second Lowel flyby

I am already in a Hohmann trajectory to Lowel, so I must start using the rockets more. 58 m/s prograde at periapsis move my orbit upwards so I'm no longer in a Hohmann intercept to Lowel, this increases my orbital speed relative to the red planet by a lot more than the fuel I'm spending.

This procedure is more efficient the lower my periapsis is. At least, I think. It worked that way when I was coming down to Lowel from Mandrake, and it does make some sense - a lower periapsis gives more Oberth effect from Gememma to raise orbit more. Though it can also be reasoned that if my periapsis is a lot lower than Lowel, then being slightly out of an ideal Hohmann intercept won't make much of an impact on intercept speed, making the procedure less effective. I'm not sure, but I think more likely it is indeed better to have a lower periapsis; which is why I'm not making a single big burn immediately to raise apoapsis a lot, but I make a small raising after every flyby. Besides, I'm still going to need course corrections to ensure the next encounter, may as well use those to also raise apoapsis.

The 1.8 m/s is the plane change to ensure I remain equatorial.

At 100k km Ammenon can be seen passing in front of Gememma with the naked eye as the slightly darker spot slightly on the left

The process was slow. Slower than using Gannovar, because I'm dealing with small changes every time. Maybe I could have been more aggressive with those periapsis burns and it would have resulted in less flybys required without significant extra cost; maybe not. This is new territory even for me.

Ollym is an additional factor around Lowel. As I already discovered, I can't really decide where Ollym will be on my next flyby, I have to account for it. Most times I did not touch it; sometimes I'd take a short detour in Ollym SoI. Sometimes I'd have to tread the needle to pass between Ollym and Lowel, and sometimes I'd just have to give Lowel a wider berth and get reduced benefit from that specific flyby. Or maybe I'd have to fiddle with my maneuvers to push the encounter one orbit sooner or later.

The closest example of treading the needle, with Boundless passing between the planets, 2 km outside of Ollym atmosphere, and 1 km outside of Lowel atmosphere

Boundless is speeding straight towards Lowel. The twin planets will move just enough that the mothership will graze Ollym to its left, Lowel to its right

I was hoping I could use Ollym to further change my speed relative to Lowel - just like you can use Tylo both to get captured around Jool, and to get ejected from it. But I can't seem to get any sizeable effect. Probably my speed is too fast, Ollym too small, to have a measurable impact.

With that, I'm doing all I can to save fuel. Depending on orbital times and resonances, it takes from 50 to 200 days to find a new encounter. Fully lowering periapsis was a lenghty process that took a few afternoons to complete.

Trajectory 6: the lower I go, the harder it is to move periapsis. Between 22nd and 23rd flybys, only 6000 km of lowering. The last flyby will provide barely 4000 km

Now Ammenon is close enough that it can be seen, with difficulty, even outside of a solar occultation

During one of many Lowel flybys, spotting a particularly distinctive mountain. If I was still on the surface, I'd try to visit there

Now Ammenon is twice as far as Mun is from Kerbin, it can be resolved with the naked eye (just to the left of Boundless)

It took 29 gravity assists. Including the ones from Gannovar. Counting the times I visited both Lowel and Ollym as a single instance. It became stale after a while. Still, eventually I got there.

The last gravity assist

It took over 8 years, countless orbits, to lower periapsis by 470000 km. Taking into account the different duration of a Kerbin year, this gives an average rate of periapsis lowering of 6 m/s. A normal running speed for a man. I have a super advanced spaceship zipping at tens of km/s, and in the end I moved as fast as a man could run.

Trajectory 7: before last flyby, planning also a final plane change

The above maneuver is before the final flyby. Current periapsis is 137.2k km, and it will be reduced to 134.9k km, a very tiny amount - but one that would still have required a hundred m/s or so. Then I have to make a 235 m/s plane change. Sucks. All those gravity assists had a significant radial component, and I took them all on the same side of the orbit. I mean, Boundless intersects Lowel's orbit in two close points near apoapsis, and I always took my flybys while on the descending side. This moved my apoapsis laterally. It was on the spot where Lowel meets Gannovar orbit when I began. That was a very convenient spot because it was also a planar node with Ammenon; I should have remained there, and I would have been able to make the final plane change for free. I just wasn't paying attention. Anyway, now I have to pay. I hope I'll still have enough fuel, else I'll have to reload from the point when I started taking Lowel flybys.

Running, once again, the calculation with the fuel consumed, I spent 1210 m/s so far, which will increase to 1450 m/s once the final plane change is factored in. I was hoping I'd do it with 1 km/s, but it's still a huge saving over the 5 km/s it would have cost me without gravity assists. I learned a few more things I didn't knew - which, at my level of experience, is a rare boon. If I were to do it again, I'd do it better. I'd be able to skip that plane change, maybe even swap from Lowel to Gannovar again at some point. I could maybe bring the cost to 1 km/s. But I'd rather not reply all the long, painstaking multiple gravity assist process, so I'll try to reach Ammenon with the fuel I have left. It looks like a close call, where a few hundred m/s may make a difference, but it's unlikely that final plane change will be what screws me up.

11.3) Making the fuel last

Spoiler

Before I try to provide 20 km/s with my current means, I want to check whether it is feasible to use Ammenon for gravity assists to repeat the process I just used. In theory it is, but Ammenon is much smaller than Lowel or Gannovar - 95 km of diameter, 0.09 g of surface gravity, and a sphere of influence extending only 70 km past the surface. I doubt it will be big enough to be worth using.

Attempt to calculate a gravity assist on Ammenon. The effect is negligible

As seen from the picture, it would lower apoapsis from 560.9k km to 560.8k km. No, definitely not something I can use.

I run some calculations. Boundless, excluding the fuel in Traveler - and factoring in that this fuel will be burned - has roughly 8 km/s. Traveler heavy stage has 10.5 km/s while carrying a full Cigar. Cigar itself has 1.8 km/s. Looks like an extremely close thing. I still have a few moving parts, though, that I'm trying to figure out how to use. The first one is Ice Cream Cone. After a bit of deliberation, I detach it.

Status after detaching Ice Cream Cone

Boundless required 1.5 km/s to reach this Ammenon transfer orbit. It will likewise take another 1.5 km/s from here to land on Ollym again - something less, because of aerobraking. Coincidentially, that's exactly the deltaV that can be provided by 125 tons of fuel. Which is the fuel that fits inside Ice Cream Cone. So, by detaching ICC, I am dumping over 200 tons of mass that I'd have to bring down and then bring back up. I will rendez-vous with ICC afterwards to recover its fuel. Boundless just gained 1 km/s of deltaV for not having to carry the heavy lander and the fuel needed for the return trip.

And I realize I can do the same for Traveler too: spend some of the fuel within the heavy stage, detach the heavy stage with some leftover fuel, finish circularization with the much lighter basic ship, then recover the heavy stage and its leftover fuel. But how much fuel should I burn before I detach the heavy stage? I was about to handwave it by trial and error, then I decided that I am absolutely capable of that kind of math, and I should not be lazy about it.

Creating a mathematical model to figure out how much fuel I must leave behind and how much deltaV I can get

I run the calculations, and the results are staggering. F't is 20 tons, and it will give for deltaV1... 4 km/s. Which goes both ways. I will have 4 km/s while lowering apoapsis, and 4 km/s while raising apoapsis, for a total of 8 km/s. Adding the 6 km/s from the regular Traveler, I have more than 14 km/s. I gained almost 4 km/s with this trick. Turning a very close call into an easy stroll.

It should not be surprising. The heavy stage has a dry mass of 15 tons, that I won't have to cart up and down for 6 km/s. Adding the 20 tons of fuel, that's 35 tons. Which is the mass of Traveler itself. Traveler is pretty small, most of its dry mass would have been the heavy tank and extra fuel he'd have to lug around.

Boundless starts lowering orbit

I split the burn because my orbit around Gememma is fast enough to entail some significant cosine losses. And because I'm not in any hurry.

Without Ice Cream Cone, there's nothing to compensate for the large asymmetrical mass of Traveler full of fuel; but it was easy to shift some fuel in the tanks to reset the center of mass where it belongs.

Splitting Traveler

A handful of comments on this picture. First, I had brought an ion engine and a couple xenon tanks in storage inside Boundless, just in case I would not be able to reach Ammenon otherwise. Better to lose some pride than to lose the mission entirely. And I'll definitely won't need that xenon, so I'm leaving it back. If this was a movie I'd be tossing it overboard for greater dramatic effect, but what the hell, xenon is expensive, I'd hate to just throw it away. Second, I still have 5 km/s left on Boundless - 5200 if we factor in the emergency fuel I left in Arrowhead. I spent some 3 km/s going down, but deltaV increased upon freeing all the mass of Traveler heavy stage. I initially used up more fuel, then I realized I could stretch Traveler more while still keeping reasonable safety, and I reloaded.

Science report from low Gememma space. Look at how much energy is produced by the solar panels!

The solar panels are still glitching. They should actually produce a lot less electricity than that, but they do produce as if their distance from Gememma was their distance from Kaywell. They still must be pointed at Kaywell, not at Gememma.

Separating the heavy stage. No pics of lowering orbit, but do look at apoapsis

The heavy stage. Calculations stated I had to leave behind 20 tons of fuel, I left 22, for safety. Since the tank has no probe core, the game things it's a piece of junk. Undignified, but not a problem

All the pieces split, and final maneuver for Ammenon. 3000 m/s to capture, 3000 to return to the heavy stage, leaving a few hundreds for safety

I spent a few seconds being concerned that one of the many pieces I left parked in orbit may collide with Ammenon, but seeing how tiny is the planet - and seeing as I won't be spending more than a few days down there - I feel safe. Worst case, I'll notice a piece is missing and will have to reload. I did check that Ice Cream Cone won't collide with Lowel for the next year, though.

Approaching Ammenon

Getting close. But still outside the tiny sphere of influence

Capture burn. The horizon shows mountains

I... have no idea what this is, but I do like it

And the molten sea, on Gememma's side

I already checked on Ammenon a few times, so I knew what to expect, but I was still amazed.

Ammenon is tidally locked. The day side is exposed to the full heat of Gememma, with a lake of lava in the point closer to the star. The night side is covered in ice. And it's more beautiful than I realized.

Landed, and science. For all that the surface is supposed to be ice on the dark side, the thermometer registers 311 K

I liked Ammenon so much, in fact, I decided to circumnavigate it. I did an entire tour of the surface, and it's a really nice little world. However, that will get its own spinoff chapter, like the other circumnavigations I did. Here, I'll just cut back to going back to orbit and rejoining Traveler.

Cigar rejoins Traveler over the molten sea

That was the last flag, the last planet. I landed on 43 different worlds (not including Mesbin, where I started), and I explored the surface of most of them. I run a few circumnavigations. I spent almost one year playing this mod - the first report is from july, but I started working on Boundless on march. Now it's time to return.

And the first step to return is to climb out of this gravity well.

11.4) Step by step, climbing up the gravity ladder

Spoiler

First, leave Ammenon to reach the heavy stage tank. Ammenon does provide a tiny, negligible Oberth effect, so I may as well make this maneuver in Gememma's orbit. But then, I saw leaving Ammenon does raise apoapsis a few hundred meters anyway, and I may as well use it. I brought some extra fuel, but not a lot.

Rejoining the heavy stage. 700 m/s to leave Ammenon, 650 for maneuver, and 1600 of intercept, for a total of roughly 3 km/s

I did burn what fuel was left in Cigar, to make Traveler lighter. I brought plenty of chemical fuel for Cigar planning use it to pay the final capture deltaV, but there was no need.

Back to heavy stage, with 500 m/s left

Now reunited, I have 4400 m/s

And up to rejoin Boundless. This takes over 3700 m/s

Boundless reunited. I have to move fuel around to restore the center of mass again. Anyway, I have 5 km/s available

And 2800 m/s to rejoin Ice Cream Cone completes the 10 km/s climb. I haven't burned so much deltaV since my Jool5 speedrun

It's been a while since I showed the rearward cupola. Now with the distinctive red hue of Gememma

Meeting back with Ice Cream Cone, 50 days after the split. It felt like forever, but this part of the mission was pretty fast

I forgot to deploy the solar panels on ICC, so it was dead. Had to send a crew to open them manually to restore the ship, and I took the chance to snap this nice picture

Boundless reunited, in a Lowel transfer orbit, and I have 3 km/s available. Also, check the ridiculous production of a gigantor here

With that much fuel, going back to Lowel would be a lot easier than going down. However, I don't fancy having to refuel Boundless, only to spend all that fuel just to leave Gememma. So I will try instead of taking gravity assists to leave Gememma entirely, and land on Oshan. This way, I'll be able to land the crew back to Mesbin with only one refueling stop, and I won't even need a full load.

Edited January 28 by king of nowhere

[king of nowhere]

Part 11B: The land of molten rock and frozen water

This spinoff chapter details the circumnavigation of Ammenon. I can drone on how much I liked the little planet without cluttering the main chapter worse than usual.

Spoiler

What attracted me to the little planet is the variety of terrains. On most planets, even good-looking ones, you can expect one type of terrain everywhere. Little variation. My favourite circumnavigation is the one of Slate, because Slate had an interesting geography. Well, I'm now putting Ammenon as number 2.

Landed on Ammenon

Let's get started

All the pics here are in natural light. This is the light of Kaywell, coming from very far, but still enough to see. Without Kaywell, it would be completely dark.

A later picture taken at night, for comparison

Land is quite irregular hills

I landed on the dark side, fairly close to the terminator line, because I wanted to immediately see both types of terrain. So far I'm finding highlands environment, many craters, many irregularities.

Solar panel production

Kaywell is very far, but the solar panels are still decently effective. That's a glitch; they were a lot less effective already around Reander, and here I'm much farther.

That's still not much electricity. On flat land, it's enough to accelerate and keep speed while the batteries slowly recharge. On those hills, I need to accelerate more often, and the batteries eventually get depleted, forcing occasional pauses.

An interesting double crater

One of many explosions

Cigar is a pretty crappy rover, unsuitable for this terrain. The docking port and engine are extending way past the wheels, making them susceptible to hit the ground on steep inclines. I needed plenty of reloads. I was actually very tempted to just give up on this and use instead my trusted Leaping Mantis rover - which I would send here with a crapton of xenon. Even spending hours doing huge burns to get there, Leaping Mantis would be able to go twice as fast on this terrain, and much more safely.

In the end, I choose to use Cigar because it just felt better to have this mission be part of the grand tour. The one saving grace I could hang to is that in whirligig world the altitude limit to time warp is very low; as soon as you are airborne, you can time warp. Sure, you crash if you hit the ground, but for a brief time, you are considered on orbit - and then you can save the game. Normally, you must be at least 500 meters of altitude to save. Instead, I can save the game every time I take a long jump. This let me save every few kilometers, without having to stop every time. And being able to save often brings the risk to a manageable level.

Gememma is starting to appear on the horizon. Kaywell is the bright spot in the sky

Those sci-fi settings where a planet has a tiny habitable strip near the terminator line must look something like this.

Science from dayside biomes

There are four biomes on Ammenon; ice caps, for the dark side. Highlands and maria, for most of the day side. And molten sea, the lake of liquid rock that sits directly underneath Gememma. So far I'm in highlands terrain, maria are smoother. Ice caps also has highlands and maria areas, in that it has smoother and harsher places, but it still only counts as one biome.

By the way, do look how, despite the message on the scorching sun, the recorded temperature is actually lower than it was earlier on the dark side. Well, temperature worked really nice for the lava biomes on Yalthe and Yokane. I won't complain if it glitches here, it's not as important. And I won't have to worry about Gememma melting Cigar as it passed under the zenith.

Gememma peeking gradually out of the horizon

Dayside highlands. Still fairly difficult terrain, but I have functionally infinite electricity

It must be noted that while the terrain is rugged, it's also very level. I don't remember ever coming close to 2000 meters of elevation; I rarely went above 1500. While for lower elevation it's around 900 meters, except around the molten sea where it reaches 0. And except some some glitches that I'll discuss soon.

Even now that I'm exposed to the sun for a while, temperature is still low

What is that bright spot I see on the map? Can it be a mountain so high that it can see the sun from there?

Wow, it actually is! Not a mountain, but a pillar

WIth a monolith on top (I went here with alt-f12 to check, obviously)

At first I thought I stumbled upon an easter egg. Wow, what are the chances? I would have never found this place except for that trick of light in the map, because the pillar was in the exact right spot for it. Who knows how many more easter eggs like this I missed.

Then I checked the coordinates, and realized it's in the same spot as a monolith on Mun. So it just means Mun was used as a model for this planet, and it has the same anomalies. Indeed, I went to check other locations of black monoliths on Mun, and they also have pillars on Ammenon

Like this one

I don't know if it's intentional or a glitch, but I doubt it's an easter egg.

I actually did found a real, genuine easter egg during my grand tour. However, the mod creator has asked me to not disclose it, so I won't say anything except that there is one to find, for all those who may be interested in this planetary pack.

Solar panels drama

Remember, while I'm getting tens of thousands of electricity per second, the panels must still be aligned with Kaywell to produce. When Kaywell goes behind the horizon - or even behind Gememma - the panels stop. When Kaywell is occluded by Limnel, the panels stop. Nothing a short pause can't fix anyway; Ammenon rotates every 7 hours.

Incidentally, I'm driving against the direction of rotation, and almost at the same speed as the planetary rotation (which is around 20 m/s at the equator). So I'm experiencing much longer days. Kaywell days, because Gememma is always sitting still in the sky.

More highlands

Here highlands give way to maria

As you can see, maria are much smoother. I can run a lot faster, and I don't remember every exploding while on that terrain. If the whole planet was like that it would be boring, but it's certainly refreshing to have a breather after much hill driving.

Current position of Cigar. Highlands terrain looks rugged even on the map, while maria can be recognized

Cigar will now turn slightly south, to turn around the molten sea. It will be maria terrain all the way.

On maria, enjoying the easy ride

There are occasional highlands inclusions in maria, but they do look partially submerged

Which is another thing I really liked. Geology is basically random in this game. There are craters, and that's it. Mountains may look good from afar, but from up close they rarely do look like real mountains. Well, those craters do look like craters that were then sumberged partially in lava, with the aforementioned lava filling all the lower ground and covering it with a smooth surface, from which the highest points still emerge. Which hints that in the planet's past there were massive eruptions that covered vast swathes of Ammenon.

First sight of the molten sea

You can recognize this canyon and gulf in the map a few pictures back. I did not went down here, as it would be more difficult to come back on track. Instead I waited until my course brought me closer to the liquid.

Here is where I'll dip in the lava

More evidence that Ammenon may have some sort of water-equivalent cycle with low-melting minerals. But the thermometer data still does not match

Swimming in lava! Wow!

Wheels don't work while floating, so I'm rotating Cigar to provide some limited propulsion and return on the shore

So, wheels do actually work - as paddles. I even considered crossing the sea like this, but I can get to maybe 0.5 m/s, so it's not a good idea.

Directly underneath Gememma, the light is scorching. Sometimes it's painful to see

I tried to compare different light settings. -100% light makes no difference whatsoever. While increasing light does have a visible effect

Going down another canyon

There are a few such canyons leading into the molten sea - more evidence of rocks flowing regularly and carving the land. This is the last one; after this, the shore turns north, and Cigar will keep going west - but turn slightly north to return on the equator. Terrain has been highlands around the molten sea, but will now gradually shift to maria. Slopes have not been a problem due to the low gravity (0.09 g).

Terrain transitioning to maria

More of those semisubmerged craters I like so much

Cigar seen running up the side of one such crater

Speed record. The wheels can't go this far, but there was a slight incline

As Cigar moves westward, I find shadows again. I sort of forgot they exhisted

Weirdly, it's hotter here in the shade than it was in the molten sea

Once more on the ice cap. I passed the halfway point two flags ago - I've been planting a flag every 20 km

Approaching a Mun arch - the one that would be sitting on the northern rim of the east crater. I turned north partially to cross it

Passing through the arch

Now truly on dark side

I was worried about the darkside part of circumnavigation, because I was having electricity problems. But it turned out fine. From the terminator line to almost the first flag, the dark side is uninterrupted flat maria. I was able to drive 20 km, stop, plant a flag, save, repeat. I kept sustained speeds around 25 m/s, and never once I crashed the rover. And since my movement compensated for the planetary movement, I didn't even need to stop for the nigth. It was the fastest part of the circumnavigation. Which, at this point, was a welcome turn of events; one always faces fatigue near the end of such a long trip.

The first flag becomes visible at 100 km of distance

But now the easy part is over, there are mountains again

More highlands terrain

And craters

And suddenly the solar panels are producing a lot less than they used to

I have no idea why. One moment they were working, then they lost efficiency. This is way too little electricity to do anything. Even shutting down SAS and communication, and putting the probe core on hybernation, the batteries are losing charge. Eventually the event passed, I'm not sure what I did to fix it. As much as it can be considered fixed, as we already established the panels are glitching.

Finally, reached the first flag

A side view of the route, showing the turn southward to cross the molten sea

If I could come back, though, I would go for a polar route. I missed the polar terrain.

And now it's time to leave this planet for good!

It was definitely a great place to circumnavigate. Number 2 on my favourite circumnavigation, despite having a crappy rover. Though I doubt it could have beaten Slate as number 1 anyway. But definitely better than any other place I circumnavigated, except Slate.

If you have a mind for it, pack a ship full of xenon and come to Ammenon for a ride!

Edited January 30 by king of nowhere

[king of nowhere]

Part 12B: No wheels, no rockets, no problems!

Another spinoff chapter. I realized Didd, the submoon of Valyr, is so small (only 400 meters of radius) to allow a unique record: running a whole circumnavigation using only reaction wheels as propulsion. And since I was already headed to Oshan for refueling, I took the chance to get this silly achievement. In fact, I made a point of never using rockets while in the moon moonlet asteroid puny rock sphere of influence, using reaction wheels also to return orbital.

This is part 12B, there's no paging error. Part 12 is the last one, so I want to close with the crew returning on Mesbin.

Spoiler

You probably forgot about Didd. It was a mostly pointless experience. Just a rendez-vous with an asteroid, except this asteroid had its own supposed gravitational field. Which is not perceptible without time warp. However, I realized its minute gravity allowed for setting a peculiar record. Hey, a silly record still gets an entry in the world guinness, so I may as well be the first one to complete a whole circumnavigation without using any kind of propulsion mechanism inside a celestial body's sphere of influence, except for pushing the spaceship body against the ground with the reaction wheels.

Didd is so tiny, I could size-shame it for hours.

Here I am at less than 2 km from the surface, and still outside the SoI

When outside the sphere of influence, Didd is seen all black. It looks some sort of glitch. One that does not need fixing, as there's nothing to see on Didd anyway.

Why do I even take the effort to capitalize letters for such an irrelevant object?

Traveler approaching at 3 m/s

Some curious artifacts on the texture. Not visible on the ground

Traveler is lithobraking from escape velocity! Omg coming from outer space without slowing down it will crash for sure!

Another shot that best shows Didd. You can also clearly make out the green monolith on top. Because yes, this is technically a celestial body, so it ought to have a green monolith

And here Didd in map view. This is the closest magnification that can be achieved. Map view is pointless here

I picked Traveler for this mission because I specifically wanted something that wasn't a rover. I could have sent the whole Boundless, just for show, but I didn't want to add more refueling trips with Ice Cream Cone.

Huh. For one refueling trip, I missed the chance to have the biggest vehicle to perform a circumnavigation.

To move, I start pointing Traveler along the north-south axis. Then I pull the nose down (or up, depending on how it's oriented). The sequence below comes from further along the circumnavigation, because I didn't think to take pics of a whole sequence at first.

Start by standing still. Any small lateral speed may throw me off course

Start pointing the nose down, picking up speed

More speed

More speed!

Too much speed, actually. I learned to aim for 0.4 m/s for small jumps, and 0.7 for long jumps. Above that, Traveler is going to land on the other side of the celestial body rock large speck of cosmic dust. And I have too little control over my trajectory. And even if I did, the border between doing a land circumnavigation and taking a few suborbital jumps is a bit muddled on this body, but I'm trying to stay clearly on the side of "moving on land".

Speed achieved is mostly vertical, so Traveler goes up. Look at apoapsis, and time to apoapsis

So far I'm going in the right direction, I started at 60 N and am now at 72 N

But the poles are small, aiming for them is hard. Traveler is falling back south

https://imgur.com/undefined

And it ends at 58 N and 94 E; one sixth of a circumference away from where it started

This jump went poorly, so I reloaded. I gradually learned to improve my aim, but I also became more and more picky on what I'd accept as a good outcome. Overall, few jumps succeeded at the first try.

The very first jump. I still hadn't gauged the appropriate strenght, and I overshoot

The flag in the crater comes from the first landing. The other flag is the one I just planted. I flung Traveler on the other side of Didd

Since map view is useless, I named the flags after their coordinates, to be able to reference them

Some better jumps at lower speeds

Matters are complicated by Didd rotating fast, one rotation every 90 minutes. Speed at the equator is 0.5 m/s, which is half the orbital speed. And sure, Traveler starts with the same speed as the ground, but as it goes up by 100 meters or more - one fourth of the planetary radius - I really feel the Coriolis effect. Sometimes I get thrown wildly off course in the west-east direction. Another reason to keep those jumps low.

Planting a flag, while you can see the previous flag

Same, on a bigger scale. Every jump only covers a few dozen meters. the distance marker activates above 160 meters, and there are two flags within that range

Which is also what makes me feel confident I can claim to have circumnavigated Didd on land - or at least, as much on land as it was possible on this poor excuse for gravity.

The closest I came to the monolith. I wanted to land near, but I already mentioned, aiming was bloody difficult

Another instance of landing just a few meters from the previous flag (top right of the image)

Close to the south pole. You can see the terrain glitch on the center right of the image

The south pole, seen from above

And the path taken so far

There is a gap between two of the flags, where I got deviated east, but aside from that I did a fairly good job at keeping a straight course. What am I saying, I did an amazing job and I am the best in the world at keeping a straight course on reaction wheel jumps. I say that with confidence because I doubt anyone else ever tried to do this.

Here showing once more the petty size of Didd. Those flags are on the other side of the celestial body, and they are less than 900 meters away

This time Traveler is rolling on its side

Sometimes I'd end up on the wrong side of a slope, like above. In this case, the normal mean of propulsion would launch me mostly perpendicular to the terrain - which, on a slope, may mean going backwards. In this case, rolling gently on the side offers more grip and more precision, at the cost of less speed. The solar panels are perfectly safe, I'm rolling very slow.

Approaching the north pole

Closer to the poles, I jumped more slowly. The poles are small and difficult to aim. Overshooting one would break the chain of flags, and could mean getting completely lost in the east-west direction. Coriolis effect is also stronger when moving closer to the poles. I wanted to plant flags well above 80 degrees on both sides.

The north pole glitch. Some planets have towers kilometers high. This is the midget equivalent

And approaching the starting flag

Actually, that's the second flag I planted. The first was 3° S, but a lot farther east; in the interest of having, as much as possible, a continuous line of flags, I skipped it.

Coming within 30 meters of the starting flag, overshooting it. I can consider the circumnavigation successful

The line of flag. Could have been a lot worse

Another perspective on the line of flags

To launch to space, I needed extra strenght. So I lifted Traveler a bit, and I started rotating to pick up more speed

I got 1.7 m/s

Which is enough to exit the sphere of influence

Edited February 11 by king of nowhere

[king of nowhere]

Part 12: Bring them back

It was very difficult to go to Ammenon, it is also difficult to return. Boundless has completed all the landings, now it will bring the crew back to Mesbin (after a refueling stop on Oshan). I didn't envision a vehicle to land the crew, so I had to improvise one with what I had. Mission is completed successfully.

All nine crewmember home safely.

Yes, that's home. In this mod, kerbals live on Mesbin, which has no atmosphere. I swear, this is not any of a dozen other unremarkably grey celestial bodies

12.1) Seeing red (Lowel flybys)

Spoiler

It took an inordinate amount of gravity assists to lower periapsis all the way to Ammenon, and now it will take another inordinate amount to raise it again. And that's regardless of where I'm going.

This last part of the mission has become a slog. I feel like in those last 3 months I did nothing but gravity assists on smallish planets - interspersed by refueling stops. I'm tired of that, so I'm looking for the fastest way out. Given that I cannot avoid dozens of gravity assists on Lowel, my next destination - since I saved a bunch of fuel and I still have 42 years of life support - will be Oshan. From Oshan, I can load a third of the fuel on Boundless and still return to Mesbin. Oshan - or any other destination in the inner system - can be reached by gravity assist from Mandrake. Going from Lowel to Mandrake requires 5 km/s escape speed from Lowel, which I already have. So all I have to do is revert that speed from slower than the planet to faster than the planet. It will take a while.

First gravity assist. I need 250 m/s to fix inclination first. Periapsis will be raised only by 6000 km

We're back to counting Lowel flybys

Trajectory for 10th Lowel flyby, one year later

Those first 10 flybys had a small effect on the orbit, but I'm getting farther from the gravity of Gememma, I'm gaining more and more ground at every new assist. I spent very little fuel, only 50 m/s in course corrections. Orbits are fast, I'm prioritizing the saving of fuel. As orbital times will become longer, I will have to sometimes favor the saving of time instead.

Trajectory for 15th Lowel flyby; another year has passed

This is significant because I'm pushing apoapsis past 1 million km. Effect of flybys is more pronounced on apoapsis than on periapsis now.

Trajectory for 20th Lowel flyby, after one more year. Orbit raised to the level of Gannovar. 100 m/s of couse corrections spent for the last 10 gravity assists

Trajectory for 28th Lowel flyby. Orbit raised to Mandrake

Those last 8 gravity assists took two and a half years and 150 m/s; as orbital time is growing, I need more time between consecutive passages, and I sometimes use more deltaV to save time. I still have plenty, but I will need some 30 years for the Gememma-Kaywell transfer.

From where I am, I could eschew Mandrake entirely and just achieve Gememma escape speed, counting on the red dwarf's massive Oberth effect to propel me to my destination. Except that my orbit has the wrong alignment for it, if I just raised apoapsis I'd get flung away from Kaywell entirely. And with Gememma having an orbital time of roughly 160 years, I can't wait for it to move in a more convenient position. So I'll use Mandrake and Rutherford to achieve the right direction.

This short passage does not convey how frustrating it was to take those 28 gravity assists in sequence. Figuring the tricks out is fun, but once you have them figured out, doing it 28 times in a row is a slog. I'm only one flyby short of beating the newly established record for consecutive flybys, and with the blue twins I'm going to beat it already.

Trajectory to Mandrake

To reach Mandrake, I'm spending 120 m/s and - possibly worse - getting a very non-Hohmann trajectory, with higher intercept speed. But alas, Mandrake has an orbital time of 2.5 years, and this was the only way to catch this transfer window without having to wait that time. It justifies 120 m/s spent. The 40 m/s are instead just a plane change.

As for the higher intercept speed, I'm counting on a gravity assist from Rutherford to get captured anyway, so I don't intend to pay any extra.

And the arrival at Mandrake

Highlighted in the picture how close I came to the atmosphere. To burn off all that excess velocity I needed to pass very close to Rutherford; a bit faster, and the trajectory would not have worked.

At the end, I am captured with a very high apoapsis, from which I can leave when it's convenient.

12.2) Seeing blue (from Mandrake/Rutherford to Tyepolbynar and Valyr)

Spoiler

Hello blue twins, nice to see you again. And by the way, those will be flybys 29 and 30

Rutherford is beautiful backlit by Kaywell

Kaywell just below the horizon, no light amplification, so that the atmospheric glow can stand out

Ok, now that I am around Mandrake, I must also find a way to get away from it, in the right direction. I picked a very elliptic orbit because it gives the chance to tune very well the next encounter with Rutherford.

Trajectory to exit Rutherford...

... and reach Tyepolbynar

As can be seen from the image, Rutherford is currently on the wrong side of Gememma for ejection, but if I wait 200 days, I can exit on the red trajectory, which points on the correct direction. For that I spent 70 m/s to get the Rutherford flyby in the right place. The problem is managing to get out of Rutherford in the right direction - I entered in a retrograde orbit, and I'm also exiting retrograde. This complicated finding gravity assists. I could have turned the orbit around at apoapsis, but it would have been 300 m/s not worth it. I had an awkward maneuver, but I got by without much additional cost. Maybe I could have avoided coming in retrograde in the first place; I did because it was more convenient to get a Rutherford flyby, but I ended up regretting it.

And last passage on Rutherford; gravity assist 31. So far, it's been 8 years and a half since I left Ammenon

Planning for Valyr already

Once in the inner Kaywell system, I can't go directly for Valyr; coming from Gememma, I'd have a very high intercept speed, more than I could aerobrake.

Ok, I saved quite a bit of fuel, probably I could do it. But I am trying to do art here, and that requires being efficient with maneuvers when possible.

Anyway, I need to lower my Valyr intercept, and this requires going to Tyepolbynar. I could have gone also for another giant planet, but with its fast orbit Tyepolbynar is the best guarantee that I'll get an encounter without spending a fortune. Tyepolbynar revolves around the sun in 270 kerbal days, and with a 24 year travel time to get there I can easily adjust if it's on the other side of the orbit when I come at periapsis. I did not look for Mesbin flybys, I should have. Maybe I would have found better.

Anyway, from Tyepolbynar I get a trajectory to Valyr. Not too difficult, except I'm running out of time. My first experiment, the picture above, arrives on Valyr 6 years after Tyepolbynar. But Oshan is in the wrong side of the orbit, and it rotates too slowly. With the moons of Jool you can decide where to encounter them, but with a planet that rotates faster while the moon rotates slower, moving the encounter with a moon requires moving your orbit significantly. It would have been too expensive. Which means, I had the deltaV for it (or even for a direct capture by burning at Valyr periapsis), but I'm trying to create art, I'll save fuel.

Final plan for Valyr

So I picked another, longer trajectory. Which has the acced benefit of being in a Hohmann intercept, resulting in less intercept speed. I am counting on aerobraking it all anyway, but there are limits to how much Boundless can aerobrake.

Time is stretched to the limit. I started from Oshan to Ammenon in 157:411, so I have until 207:411 before life support runs out. And this trajectory will bring me to Oshan on 157:200. Well, I suppose my kerbals won't be able to use the swimming pool, as all the water will be used in the greenhouses. Yes, there are greenhouses on Boundless, and you can use the main water storage tank as swimming pool. Because I say so. Water is always recycled and purified anyway.

Approaching Tyepolbynar. I forgot how Kaywell and Lowel looked from close enough to tell them apart. I also forgot how comets looked from up close

Thirty-second and last flyby, on Tyepolbynar

Oshan approach; 1870 m/s intercept speed

Intercept speed on Oshan is rather high; I had a low solar periapsis. Adding the escape velocity of Oshan, it should translate to 3200 m/s of speed at periapsis. And I know Boundless can take 3400 m/s^{[citation needed]}, so I should be fine. Besides, while I could slow down with some more gravity assists on other planets, I have no more time for it.

12.3) Seeing red, blue, and a bit of white and brown too (Oshan, refueling, and Kerbmun)

Spoiler

No, Boundless cannot take a hard reentry at 3400 m/s

Ok, I see my mistake. I did aerobraking at 3400 m/s on Kerbmun, but I could only stay in the high atmosphere and brake 60 m/s without exploding. Here I have to stop entirely, which requires going much deeper. And in those conditions, I'm going too fast.

Ok, I have to slow down a bit more first. As for the art of reducing rocket burns to a minimum, well, I did what I could.

Reducing periapsis speed

By trial and error, I established I had to spend 700 m/s; reentry at 2400 m/s was just slow enough to not melt the ship

Indeed, after inching extremely close to maximum, heat bars are going down again. Also, look how low I am in the atmosphere

Finally, after circularization efforts. In the end, I spent 1700 m/s to go back from Ammenon to Oshan

Now refueling. I won't need much, I only need to return to Kerbmun. Yes, just to Kerbmun. While I'll never use Boundless again, I always loathe wrecking my motherships. Just like I did for the DREAM BIG, the Flying Christmas Tree, the Marco Polonium, Bolt, A'Tuin, A'Twin, I'll take some extra care to park the ship in an orbit from where it could be potentially reused. Or at least I try to, in the case of A'Tuin I failed. So, I also want to keep Boundless reusable.

And for that, it's really pointless to climb down Mesbin gravity well. It's very expensive. I'll park Boundless around Kerbmun, where it can leave easily. As for how I'll land the crew, we'll get there.

Very nice pic of Ice Cream Cone landing

With more empahsis on the atmospheric glow of Oshan

And a wonderful showing of Valyr and a comet in the sky

While I was there, I also sent Traveler to undertake the circumnavigation of Didd, as detailed in 12B.

Well, I won't bore you with another recounting of filling the tanks one trip after another, it was already boring enough for me. Did I already mention that I'll never, ever make an isru mothership that can't land whole? Yes, I know I did, I'm just reinforcing the concept.

Then it's time for Kerbmun. Transfer is easy.

A normal Hohmann transfer to Mesbin

Approaching Kerbmun

I made a point of aerobraking as much as possible to save some fuel, but it's not worth showing here.

12.4) Parachutes? where we're going, we won't be able to use parachutes

Spoiler

Already a few months ago, I realized a slight oversight in my careful planning. While I had brought landers for all worlds, and I had estimated deltaV needs, I never considered how I'd land back on Mesbin. Normally you land on Kerbin, so you can just aerobrake any vehicle and land on a parachute. But not here. Landing on Mesbin is akin to landing on Tylo. It requires some less deltaV, but a higher thrust, as apparent gravity is 1.3 g at the equator. Well, I had months to think through this problem, so I already had the solution.

But it's only by mere coincidence that I had the vehicle for it.

I already complained about the design issues of Ice Cream Cone. It does its job, but it could be more efficient. I gave it a wildly bloated thrust, because I was planning to use it on high g planets. Before considering that all those planets have too-thick atmospheres to work the wolfhound engines anyway, so I just strapped a lot of unnecessary engines, making my refueler more heavy, reducing the amount of fuel I can carry at every trip.

But thanks to that lucky design oversight, now Ice Cream Cone, when empty of liquid fuel, has enough thrust to land on Mesbin. And enough deltaV too. It's surprising how much performance you can squeeze out of a tanker when it's empty of all the cargo.

ICC can land, but it does not have the deltaV to orbit again. It could mine fuel on the groud, I suppose, violating the "only refuel on atmospheric bodies" rule of the challenge. But it's not needed, I have better. Traveler is the only ship I have that can carry a significant crew. It can carry 6, in fact. And ICC can carry 3, so together they have the 9 seats needed for all the crew members. And Traveler is light enough to be carried by ICC without losing too much performance (empty Traveler is 14 tons, empty ICC is 65 tons, plus 70 tons of fuel).

ICC + Traveler detaches from Boundless. This is the last time the mothership will be seen. Science is transferred to ICC

And the reentry vehicle starts its climb down Mesbin gravity well

It will take 4500 m/s to circularize

While ICC has the thrust to land, Traveler has two efficient Nerv engines. And ICC has some large liquid fuel tanks. I made the calculations, there's enough deltaV to circularize. No need to bring out the heavy stage. I could also save some by using Greymun for gravity assists, like I did on the way out of Mesbin, but no way I'm taking more chained gravity assists right now.

Only issue is that Traveler has two meager, low thrust Nerv engines to push a vehicle of 200+ tons. I spent a few hours making dozens of small burns at periapsis to achieve the 4 km/s necessary.

Coming 30 km from Statmun

Finally, liquid fuel is exhausted, but the vehicle is mostly circularized. ICC can take over from here on

Descent

ICC has enough thrust to land, but not by a huge amount. It has 1.7 TWR (Kerbin standard gravity), while gravity on Mesbin equator is 1.3 g. So, with relatively low thrust I use the strategy of pointing sligthly above retrograde to keep vertical speed constant. It's the most efficient way to make such a landing; with high thrust it makes a minimal difference and it's generally not worth doing, but in this case I need it.

Final descent

The problem of this approach is, I come down horizontal, stop in midair, and must turn upright for the final landing. And I have a tall, narrow ship. Ice Cream Cone was built with a low baricenter, but Traveler does push the center of mass too high for comfort. And the vehicle must make some brusque turns and it starts oscillating.

So it won't stay upright

I tried a few times, I always failed to make a vertical landing. Probably I could have achieved it if I stopped a bit higher above the ground. But I settled for a crash-landing that would spare the crew cabins. Fortunately they are in the center of the structure, so they are relatively protected.

If you can walk away from a landing, it's a good landing

Ultinately, I decided to not try to salvage the vehicle at all costs. It wouldn't be able to leave Mesbin anyway, and narrowly surviving a crash landing makes for a cool story.

Final science report. I transmitted back all the science I could; on top of the screen you can see the total collected in the mission

And that's the end. The grand tour was fun, but overly long. Landing on 44 bodies becomes stale after a while, as most of them are small moonlets without anything remarkable about them. Though I have to admit, every celestial body had something distinctive about it.

I already recommended this mod several times, but it's worth repeating: this is a great planetary pack.

And now, once more, I need to find another challenge.

Edited February 13 by king of nowhere