The starry heavens above me, a sturdy rover enclosing me 3; blast from the past

[king of nowhere]

This is going to be my third report of this series, dedicated to rover circumnavigations. What? You've been looking, and there is no second installment? That's true, because my second rover circumnavigation - of Wal - is still halfway. It's going very slowly, because it turns out Wal is a lot uglier than I anticipated. Meanwhile, I got an idea and I wanted to at least start it.

The idea was to run a circumnavigation of Polta, another OPM moon of Urlum. Back when I landed there in the A'Tuin mission (chapter 9.5), I really liked Polta. I went as far as calling it my new favourite solid body. So, perfect place to circumnavigate. But I couldn't do it in that mission because it was inside a radiation belt.

Here exploring it with the rover I had for that mission, the Horseshoe

For the occasion, I also wanted to bring back from retirement my old first rover, the Dancing Porcupine

So called for its strut armor devised to protect it from the consequences of reckless driving in low gravity, this rover was my first major accomplishment in this game, and I did drive it for thousands of kilometers - especially in my Jool 5 science challenge. I'm still very fond of this rover, and it still offers a fun driving experience.

As I adopted kerbalism to make the game more difficult, I tried to adapt this rover, but I couldn't. Dancing Porcupine is made to be self-sufficient in a long trip. Once you add in the requirements for food, decent housings for the crew, and replaceable spare parts, the whole concept couldn't hold. I would need to couple it with a mothership, but that defies the whole purpose of this rover. Also, Dancing Porcupine relies on its rockets to climb steep inclines, because it has low wheel power; and without the easy ISRU offered by stock, this function just couldn't be sustained.

Now I'll get a chance to drive again on that moon I like so much, using this rover I like so much. Or at least, I will get a chance once I finish my current Wal circumnavigation (which will probably get its own report eventually).

Edited February 5, 2023 by king of nowhere

[king of nowhere]

Part 1: Pit stop amid the rings of Sarnus

Dancing Porcupine doesn't have enough fuel to reach Polta in one go, so I decide to stop for refueling in the tiny moonlets of Sarnus.

Turns out, Dancing Porcupine didn't have enough fuel for that either; I had to pull off some tricks to barely manage it.

About to land on Ovok

Spoiler

Dancing Porcupine can do many things, but one of the few things it cannot do is orbit from Kerbin's surface. So it's got its own dedicated launcher.

Launcher on the launchpad. It is slightly tilted because it is optimized to orbit without manual steering

Losing the first boosters

Next stage is a mastodon engine. I don't think I ever used it for anything else

Remove the aerodinamic cover. It could have been quite spectacular, but the one on Tamarromobile was a lot better

Jettisoning the last piece of the launcher, now Dancing Porcupine is on its own

And it finishes circularizing

I made a few modifications to the rover. First, as I'm going very far from the sun, I took away all the solar panels and I put in more rtgs. Second, I strapped a relay satellite on its back. Wait, why am I using a relay satellite? The stock game doesn't give any benefit from it. Well, all my circumnavigation missions so far brough relay satellites, so it's for the sake of tradition. It also has the rovemate probe core to detect anomalies.

The trajectory to Sarnun. Pretty straightforward. After months of rss, I'm surprised by how cheap are manuevers in the stock game

I could have gone to Jool, refueling on Pol, or on Sarnus, refueling on Ovok. The first is cheaper, but the second offers the better view.

Capture at Sarnus by gravity assist from Slate

For capture at Sarnus one can use a gravity assist from Slate, or aerobraking on Tekto. A'Tuin went aerobraking because it was supposed to stay around Tekto, which is the only moon outside of the radiation belt. Here I'm using the stock game, I don't have to worry about radiations, and Slate is closer to my target.

Unfortunately, as I get closer to Sarnus and start planning a route for Ovok, I realize my mistake. Ovok is close to Sarnus, I need a lot of apoapsis lowering to get there. I don't have enough fuel. So I start using the other moons for gravity assists.

Trajectory around Sarnus, part 1

In this first part of the trajectory, after gravity capture from Slate I reduce apoapsis a bit with rockets - yellow manuever, 86 m/s, cheap enough to get more convenient trajectories - to get an encounter with Tekto, shortly after the purple manuever - which is mostly plane change. I will use Tekto to raise periapsis, because if I take another gravity assist to lower my trajectory at this point, I end up colliding with Sarnus. Tekto ejects me on the red dotted trajectory, which is suited for a Slate flyby later.

Arrival at Sarnus. Slate is clearly visible. The smaller moon is Eeloo, which the OPM mod moves in this position

Slate flyby. Dancing Porcupine is Flying over the Muil Plateau, straight above the path taken by Tamarromobile so long ago

Passing close to the rings, and very close to Ovok. But too fast, obviously

Ovok and the rings seen from the driving cabin. I didn't take many picks of the rings because the ones I got with Arrowhead in the A'Tuin mission are better

Tekto flyby

Tekto is another world I'd like to explore in detail one day. Possibly with a propeller plane. Unfortunately, I couldn't do much with Arrowhead because a bug caused the propellers to not produce thrust. So I'm wary of trying it again. I considered landing Dancing Porcupine there, aerobraking is free and if I launch from a tall mountain I may be able to get to orbit without spending too much. Then I remember the terrier engines don't work at all in thick atmospheres.

Trajectory around Sarnus, part 2

Time for an update on the trajectory. Tekto send me in this high orbit just touching Slate. A small correction manuever (yellow, 3 m/s) ensures a Slate encounter in 43 days, which I'll use to lower orbit so that periapsis falls eactly on Ovok. From there, circularizing orbit is less than 600 m/s, and I have 700, so I won't need to try and use Eeloo to further reduce Sarnus apoapsis. I'm simulating the capture burn in Sarnus space because Ovok is so tiny (even smaller than Gilly) that it has no significant Oberth effect.

I didn't take many pics of the rings, but I took some. Last time I was here, radiations were strong enough to kill the crew in three hours; this time I can relax and enjoy the sightseeing

I made a small mistake there; there was still an inclination difference with Ovok, that I had to compensate for with a burn. A small one, the inclination was only 1.5°, but it was enough to eat up my limited fuel. So as I approach Ovok...

Approaching Ovok with a severe fuel shortage

... I have 543 m/s left of fuel, and I'm speeding against the moonlet at 553 m/s. Well, not all is lost. Ovok's gravity is so tiny, it won't accelerate me further; and if I use all the fuel I have to slow down, I should fall at about 10 m/s. The wheels are rated to survive impacts up to 12 m/s, I should barely survive.

Run out of fuel at 9 m/s

Indeed, Dancing Porcupine survived the impact.

A bit of clarification here: Dancing Porcupine can easily survive losing control at 40 m/s while driving, but that's a kind of skidding-along-the-ground kind of impact. Your speed is mostly parallel to the ground, and you're mostly bouncing. A straight, direct impact like this is a lot more dangerous, and the porcupine armor is of limited use against it.

Landed on Ovok!

At least now I can get new fuel.

Edited May 15, 2023 by king of nowhere

[king of nowhere]

Part 2: The rover that went to circumnavigate Polta and ended up circumnavigating Ovok instead

Since I'm already there with a rover, and I need to get to another biome for refueling, and this moon is so small, I decided I may as well run an Elcano on Ovok too.

Spoiler

The main biome of Ovok, where I landed, didn't have enough ore to mine for the small drills of Dancing Porcupine. I need to move 10 km south to find another biome.

I thought, since I'm here, with a rover, without worry about radiation, in one of the most spectacular places in the whole game, I may as well run a circumnavigation here too.

Starting the rover

Driving in such small gravity is a unique experience, but I was prepared for it because I already did drive on Gilly (with Stool, in the Bolt mission). The thing is, of course you can't go fast, and you can't accelerate much. You just have to live with it.

Pushing the accelerator, the rover moves forward, but it also starts to roll upwards. It's ok, stop the accelerator, reactivate reaction wheels to stop spinning, now you're moving at 1 m/s. Wait to come down from your bounce, stop reaction wheels, waiting for the rover to touch on the ground with all wheels again, and you can accelerate some more. Eventually, you can pick up some speed.

Picking up some speed

Except, of course, you can't pick up too much speed, because with 20 m/s you'd go orbital. Already at 5-6 m/s Dancing Porcupine takes long bounces that encompass several degrees of latitude on this tiny moon. On Gilly, I couldn't ever go faster than 4 m/s, but Ovok is much smoother, I could accelerate more.

So this was what the average driving experience looked like

I got close to 12 m/s occasionally. And at that speed, you're not much driving as taking suborbital jumps; here the longest in all the circumnavigation

And that's basically it. Ovok terrain is very flat and very uniform, so it was just a matter of going forward. It took a bit less that 6 hours for this circumnavigation. I tried using 2x speed, but it made problems when the wheels touched the ground. I could have activated it when airborne, but really, I found more convenient to just put the game in background for a few minutes.

Without light amplification. You can't see much, but then, there are no obstacles on Ovok

Reached the next biome, planted a flag and stopped for fuel. Notice the radiators extended

Refueling for 26 days

I got very fast. That's more than half orbital speed

Stopping the rover and accelerating again takes very long. To avoid it, I send out a kerbal to plant flags with the rover still moving. Then I catch up with the jetpack

I planted a flag every 8-10 km, but I almost never stopped the rover.

Now that I have fuel, I could have actually used the rockets to push downward and drive more easily, but I didn't want to do it. This is supposed to be an Elcano challenge, and in this tiny gravity it's already hard enough to distinguish a wheeled circumnavigation from a low orbit. I only used the rockets twice to assist braking; once in the south pole, because I was about to drive through the terrain glitch. And the other in the end of the circumnavigation, because I wanted to stop right next to the first flag, and brakes are nearly useless in this gravity.

Some stunning pics of Slate crossing the rings

The south pole, with its glitch

Still the south pole

And this is the north pole instead

More from the north pole

There's a sort of butterfly-shaped terrain here

I planted a flag right over it. Also, Eeloo and Slate looking gorgeous

And Hale, the last moonlet of Sarnus

I actually cheated for that last pic. You can only see Hale like that when it's passing next to Ovok, and you need the right conditions of light, so I stopped after the circumnavigation and started time warp until I got just the right position and illumination.

Returning to my first flag, finding another glitch: it's hovering in mid-air. Or mid-space, since there is no air here

And there we are, circumnavigation complete

The bunch of flags planted around the moonlet

Edited May 15, 2023 by king of nowhere

[18Watt]

On 8/27/2022 at 1:37 AM, king of nowhere said:

Since I'm already there with a rover, and I need to get to another biome for refueling, and this moon is so small, I decided I may as well run an Elcano on Ovok too.

Nice!  Once again, I really like your use of the Cupola!  Ovok looks every bit as frustrating as Gilly, but then it would also be every bit as rewarding once you finish.

I've added a leaderboard section to the Elcano challenge for mod planet entries.  I would call it a work in progress.  I think we have a similar idea on doing that, simply having a single category for mod planets, and stating the planet (or moon) circumnavigated next to each entry.

My memory isn't perfect- I only recall you having an entry for Slate, and now Ovok.  (With another one coming soon!).  If I have missed one, please let me know.  

I have not started working on a badge yet.  I'm thinking the badge would be similar to the other badges, but perhaps with a '?' question mark or 'X' in the center.  I'm open to additional ideas regarding the badge, if you have any thoughts I'd love to hear them.

I think you are the first player to submit an Elcano entry for a mod planet.  Those entries have always been welcome, but we just have never had a leaderboard for it.  Now that a leaderboard is in place, I find myself wondering why I didn't do that sooner.

[king of nowhere]

1 hour ago, 18Watt said:

My memory isn't perfect- I only recall you having an entry for Slate, and now Ovok.  (With another one coming soon!).  If I have missed one, please let me know.  

slate and ovok are the ones I completed.

On Wal I recently crossed the halfway line, but it will still take months.

In this continuity I'm planning to also do Hale (again, since I'm already here and it's small and it's got good sightseeing) and eventually Polta. but those will take a while, because I'm still running my main kerbalism rss grand tour, and I just couldn't resist picking up also the speedrun challenge.

[king of nowhere]

Part 3: Through sleet and Hale

Having just circumnavigated Ovok, I can't skip Hale.

The terrain is a lot harder, but the view is even better.

Spoiler

I'm on Ovok, Hale is literally just a stone's throw from my position. The sky from Hale looks even better than from Ovok, because the inner moonlet is stuck right between the two ring systems, instead of on the outer boundary.

The previous time I went to Hale, it was a daring stunt in a highly radioactive environment that required all the deltaV I could muster, some exotic trajectory to minimize exposure, and still almost killed the crew. I was too busy looking at the geiger counter and trying to be fast to admire the view. But this time there are no radiations, so I can enjoy it at leisure.

Almost feels like cheating.

Leaving Ovok

Most of this post will just be pictures of the rings, and for once I won't bother with captions unless I have something specific to say. Writing "here's yet another amazing view of Sarnus rings" several dozen times wouldn't add much. Following a bunch of pics taken during the trip to Hale. I took over 100 screenshots, I'm trying to only include the best.

I tried to capture the exact moment of crossing the rings, which really are one pixel thick. This is the closes I came to it

Hale is even smaller than Ovok, which is itself smaller than Gilly. Its nominal radius is only 6 km. Gravity is supposedly slightly higher than Ovok, due to a higher density.

In practice, though, most of Hale sits at an elevation between 2500 and 4500 m. Which, when added to the diminutive radius of the moonlet, nearly double its actual size. And since gravity decreases with distance, and the nominal value of 0.023 m/s refers to datum level, the actual gravity is often half of that.

It's still higher than Phobos, now that I think of it. And Phobos even had glitches due to the low gravity.

Anyway, while on Ovok I was able to pick up some speed due to the flatness of the ground, Hale is very irregular and bumpy. So I couldn't ever accelerate more than 2.5 m/s with wheels alone. I could go slightly faster while falling down cliffs. To speed things up, most of the circumnavigation was run at 2x speed; any faster than that, and it would mess the wheels. Still, near the end I was having troubles climbing a cliff with anything resembling speed, and I decided to "cheat" and use the rockets to push Dancing Porcupine against the ground (for the sake of the Elcano challenge, I clarify that every forward push was provided by the wheels, and the rockets were only used to simulate some gravity).

An act that crushed the wheels, even though I was using low thrust. Looks like another glitch of the game. But after reloading and figuring out the trick (no, there isn't any special trick to avoid breaking the wheels, just keep trying until it works), I dared to push my rover to the ludicrous speed of 7 m/s. Which is close enough to orbital speed that when I went EVA with Bill to plant a flag without stopping the rover, on catching up to the rover I sent Bill past orbital speed and the visual changed, rotated by 90 degrees. I ended up in some terrible limbo where the smallest touch of the jetpack would change the trajectory from orbital to suborbital, with subsequent visual rotation. It was quite annoying to get back to the rover in those conditions.

This is the south pole. On Hale there are no major terrain artifacts, though a close look will reveal those three pieces of terrain aren't well connected

The circumnavigation took roughly 9 in-game hours, for a distance somewhere around 60 km. It was slow because of the terrain, though the last third using thrusters to simulate gravity increased the average speed.

Hale is definitely worth a look, if you don't have a killer radiation mod.

 

Edited January 18, 2023 by king of nowhere

[king of nowhere]

Part 4: Updating the armor

I put this mission in undetermined hiatus four months ago for a critical problem: the porcupine armor has been made ineffective by the update that introduced EVA repair kits. That update also made wheels a lot more frail. As I started the circumnavigation of Polta, I kept suffering accidents. The mission was too impractical, the very purpose of driving Dancing Porcupine was defied.

After completing the other missions I had running, I turned back to this one and devised a way to protect the wheels. I am finally ready to actually circumnavigate Polta.

before

after

Spoiler

The porcupine armor offers excellent protection on the top and sides, but it does not cover the bottom of the rover. Obviously; the wheels must touch the ground for the rover to move.

This wasn't a problem 2 years ago, when wheels were practically indestructible. I drove Dancing Porcupine a good 3000 km between Mun, Vall and Tylo and I never broke a wheel - not unless it was a major accident destroying the whole truss. I even considered removing the struts and putting wheels in their place, as they were far sturdier.

But no more. Wheels became really frail after the EVA repair update. Yes, they are more realistic, but they obsoleted Dancing Porcupine. Meanwhile, I never really had to confront this issue because since then, all my rovers switched to active protection, that is, reaction wheels to always land upright. Stool started the trend. And wheels are pretty sturdy if they hit the terrain with the right angle.

Even Leaping Mantis, despite its roll cage, relied a lot more on active rather than passive protecton. In fact, it relied on a combination of the two: use the reaction wheels to make sure the rover would hit the ground on the strongest points of its armor. Dancing Porcupine has weak reaction wheels, it can't be directed much mid-flight; it must be protected so that it can take a blow from any side.

I have no problems admitting that active protection is a lot more mass-efficient, and my beloved Dancing Porcupine is obsolete. But it's still fun to drive. Or it used to be, while I could still rely on its indestructibility.

I reached Polta easily (Sarnus-Urlum transfer is very cheap), and landed. There I made a point to drive 10 km without breaking anything. I couldn't do it. After much trying, I decided that driving Dancing Porcupine was no longer fun in those conditions. So I put the mission in hiatus.

After completing the rss grand tour, I came back and tried to fix things.

First idea was simply to add some landing struts that would extend under the wheels, kept retracted, to quickly deploy in an emergency.

Like this

Here the new piece of armor protects a wheel from an impact that would have been fatal

Unfortunately, it wasn't enough. While the new piece of armor could deploy and protect the wheels, there was still a major source of damage that it failed to prevent.

Most common cause of broken wheels. Notice the direction of the impact

Most often, Dancing Porcupine takes a bump and turns around a bit. Then it hits the ground at exactly the angle in the above picture. This happens really fast. Sometimes the wheel doesn't even leave the ground, just sliding on the ground while the mass of the rover applies pressure in that direction is enough to destroy the wheel. The strut does not have the time to get extended.

In retrospect, I should have tested it more before sending the new rover all the way to Polta.

Then I tried to experiment with plane wheels. They worked very well on Leaping Mantis. But applying the Mantis Claws on Dancing Porcupine was ineffective. The Claws worked because they protected from a specific direction, and the active protection did the rest. In particular, while plane wheels on Dancing Porcupine did a good job protecting from impacts when the rover fell to the ground at a 10-30° angle, when hitting the ground frontally the plane wheels would hit with the non-wheel part. And they would explode.

Yesterday I tried a bunch of designs, then I gave up. Today, while driving to work, I suddenly had the right idea: put the plane wheels in front and outside the rover wheels, forming a box around them. Align them to the direction of travel and make them touch the ground all the time, so they can protect in case of sliding on the ground. Finally, put a cage of landing strut against that design, to protect from the directions where the plane wheels are weak.

After some extended testing - which also led to rebuilding the rover - I was satisfied, and Dancing Porcupine 2 was ready to go.

Front view

Bottom view. The more elaborate relays I brought are not relevant here

I changed how the wheels are attached to the rover. This added 4 trusses (500 kg) but made for a wider base and more stable rover.

Front view

I switched to the LT2 strut. It's heavier, but it's longer, giving more space inside the armor. With that extra space, I moved on the top all the stuff that was attached on the sides. As a result of the new placement, the center of mass no longer moves while the tank gets emptied, resulting in much smoother flight.

I removed the middle protection, focusing only on the angles - having a bigger cage allows that. This way I saved enough mass to compensate for the other stuff I added - the new rover is 200 kg heavier than the old one, losing only 50 m/s.

I also used 4 tanks instead of a single big one; this way I can shift fuel between them to change the center of mass if needed.

And I changed the way the engines are attached. They are more protected and more effective, with less shaking.

I kept the lights from the old rover. I took the front as it was and attached it in place. The thing is, for all my subsequent experiments I could never build a set of headlights as effective as the one of the original Dancing Porcupine.

Edited February 10, 2023 by king of nowhere

[king of nowhere]

Part 5: Going to Polta (again)

The trip from Kerbin to Polta, with refueling at Pol. Pretty straightforward.

Spoiler

Going all the way to Sarnus for refueling was not a good idea. Sure, I could land on Ovok nearly for free, but even with the best gravity assists it's still over 600 m/s intercept speed; those moonlets are close to Sarnus.

Much better to go to Pol. Going to Jool is cheaper, and after some Tylo gravity assists going to Pol is also a lot cheaper. More than compensates for the 120 m/s to land on the small moon. So here's the flight plan

Part 1: 2 km/s plus 100 m/s plane change for a Jool intercept

Part 2: gravity capture at Tylo, setting apoapsis level with Pol

Part 3: a total 400 m/s for capture at Pol

It leaves a comfortable 500 m/s of margin.

A bit less because those pics are from the first time I did this, when I only strapped four additional struts on Dancing Porcupine (we can call it Dancing Porcupine 1b). The second time, with the final version of the rover, I had two relay satellites with me, lowering my deltaV considerably. Still, enough fuel.

Dancing Porcupine 1b, landed on Polta. So much effort to scrap it shortly afterwards, I should have tested it more

After refueling at Pol, wait a few years for a nice comfortable Jool-Urlum transfer window. There is one around year 8.

Part 4: From Pol to Urlum. This far from Kerbol its gravity is small, and moving between outer planets is cheap

Seventeen years travel time pass in minutes, and for once I don't have to worry about life support and part failure. Refreshing!

Part 5: Taking advantage of Oberth effect and the orbital speed of the moon, direct capture at Polta is only 200 m/s. 400 including circularization

So, a simple enough trajectory, nothing to remark about. The second time I got captured in high Urlum orbit first, to deploy the relays; it was slightly more expensive, but in the second part of the trip deltaV is not an issue.

I still got some good pictures, so I will end this chapter with a photo gallery.

Launching Dancing Porcupine 2 the launcher is similar to the old one

Second stage cruising. It looks a bit ridiculous with that giant fairing on a tiny rocket, but the fairing is almost all empty space

Deploying the fairing

Unfortunately getting into the cupola would have messed up the rocket orientation, so I don't have internal pictures of the fairing opening

To compensate for the mass in the back, I added a small engine to correct torque. Still had to tune down the front engines a bit, and move fuel among the tanks

The best picture of the inner joolian moons I've ever seen

Unless it's this one?

Approaching Tylo

Close to Tylo

Refueling on Pol. The relays on the back made landing a bit awkward, but the low gravity helped

High above Urlum, releasing the relays

This still shows Dancing Porcupine 1b, but it's the best picture of Urlum and Polta together I have

Capture burn. Or perhaps deorbiting burn

Landing

Landed

Edited January 19, 2023 by king of nowhere

[king of nowhere]

Part 6: The ups and downs of Polta

From equator to north pole, Polta is a swirling patchwork of gentle hills and plains.

Spoiler

At first I try some night driving, as I always do.

Visibility is good enough to feel like you see where you're going, but not good enough to actually see where you're going

Floating boulders, a common bug

After getting used to Leaping Mantis, that was built for the most extreme terrains, and Tamarromobile, which was very large and on a high gravity world, I was surprised by how poor is the driving performance on Dancing Porcupine. It is sluggish, needs rockets on theep inclines, and it capsizes easily. I rarely get to exceed 30 m/s, or to drive more than a few km, before I have an accident. Well, it's the price for making a rover with rockets and a big pile of fuel.

Wal and (below it) its small submoon Tal in the sky

Soon, though, I get tired of not seeing the vistas, and I wait for the day.

Actually, I passed several days, as I occasionally stop for fuel.

Polta's swirling surface is made of lowlands and highlands, with relatively steep boundaries, like the one above. They are not too steep to be dangerous going down, though they do require rocket help going up. I am making a beeline for the pole, crossing such boundaries many times.

A view from the secondary cabin. Still a good perspective, but confusing due to the orientation

The modernized Porcupine Armor^TM works really well. In the sequence below I fall down a crater, I hit the ground at high speed, and still take no damage.

Still, the armor is not perfect, and I do have to reload occasionally. Its main vulnerability is the opening time of the lower struts: without them, the wheels are vulnerable (though the plane wheels do improve things a lot just by themselves), but it takes some precious seconds to deploy the lower struts, and before they are fully extended, they are very vulnerable. I often find myself conflicted on wheter to open them - and risk crashing before they are fully deployed - or to not open them - and risk crashing with a lesser protection for the wheels.

By the way, I am one of those that keep the same controls for the wheels and the SAS, and I use a hotkey to deactivate reaction wheels so they don't destabilize the rover during acceleration. Here I made a small but nice improvement: I added a flashing red light (visible at the beginning of the sequence)  that turns on when SAS is deactivated. Much better than keeping the action menu of a reaction wheel always open.

The rings of Urlum require the right illumination to be appreciated in full

I also had to face the ground bug: at some point the wheels just sink in the ground and stop having traction, getting stuck there. I faced the same issue in my A'Tuin mission on the moons of Neidon, and then with A'Twin on Titan and Triton.

Here struck by the ground contact bug, I am trying to use the rockets to get out of the quicksand. Notice the wheels sunk in the ground

This time, though, I made a breakthrough because I also have drills, and they say no ground contact. And this is related to another bug, again well documented in my grand tours.

How does that help me salvage this mission? The ground contact bug is temporary. So all I have to do is time warping for a bit, and it will get fixed. Though it often does jolt the wheels - which suddenly find themselves clipped into the ground - and break them.

Another thing I learned is that the bug is localized; if I push with the rockets to keep moving, like I'm doing above, chances are that soon the bug will disappear.

Here I am approaching the pole and, as is often the case, the terrain gets harsher. In the picture I am using the rockets to pass a particularly steep passage.

By the way, all the jolting through 300 km of driving had bent those rockets a bit out of shape, but a quick eva to detach and reattach them fixed the alignment as good as new.

Follow this crest straight for the north pole. Notice the long grooves aligned with the poles, a common feature of OPM planets

In the center of the image, just above the horizon, is Priax. I am high enough that I am seeing over the planet

Edited May 6, 2023 by king of nowhere

[king of nowhere]

Part 7: Swallowed by the polthole

Polta has a massive sinkhole in the north pole, just like Moho. Having rockets, I went down it all the way.

Spoiler

As always, close to the poles there are terrain artifacts making the ground a lot more irregular.

 

Driving becomes more and more difficult, though so far I'm still keeping some decent speed.

Here I suddenly exploded while driving normally. Just a case of terrain and its collision box not matching

Here I got stuck in a tight crevasse. Retracting the lateral armor freed the rover

Indeed, those lateral struts are invaluable when hitting the ground at an angle, but in this choppy terrain they hit the ground all the time. At some point I just left them permanently retracted until I cleared the 80° parallel again. It's not like I can go fast enough to be in danger anyway.

By the way, you can already see the mouth of the Polthole.

Getting close. What looks like the opening of a giant mouth in the top of the image is exactly that

And closer. Though from this perspective you wouldn't guess that the depression in front of you will go down for kilometers

Surprisingly, I went so far without needing to use the rockets much. In moving away from the pole I'll have a much harder time.

On the edge of the Polthole

Seen from above to gaze at the bottom, though the perspective is a bit confusing

Jumping down the hole

Dancing Porcupine has rockets, so why not?

After a long descent, I get stuck at the bottom

This one took some trial and error. It's very easy to hit the walls and lose control. Or perhaps to get stuck with the rockets pointing upwards, unable to ever get free.

I discovered I didn't take any picture of the flag planting, so I reloaded back and did it. Which is why in the following pictures the rover is in a different position. And from that position I probably wouldn't have been able to free it.

I didn't want to show a pic through transparent terrain, but it's the only way to appreciate the shape of the hole

Planting a flag at the very bottom

The main difficulty here is that the view uses the pole as a reference point, and when you're so close to it the game keeps rearranging the visual. Very annoying, trying to fly straight with the jetpack is hard.

Getting the rover unstuck also was difficult; fortunately, the rockets can be moved around, and the struts can also be creatively used to change its position against the walls.

Through all this journey, I often missed my Leaping Mantis rover. It's faster and more maneuverable, made exactly for a difficult terrain like this. But I have to give credit to Dancing Porcupine: Leaping Mantis could have never gone down the Polthole and back out again in one piece.

Flying out of the mouth

Howering above the pole, the view is magnificent

Landed back out of the mouth

I was tempted to use the rockets some more to skip some of the most difficult terrain around the pole, but that would be cheating.

One last image of the Polthole, perhaps the best perspective

Edited February 20, 2023 by king of nowhere

[king of nowhere]

Part 8: Getting away from the north pole

The land is so difficult here, it deserves a special chapter.

Spoiler

The terrain on this side of the pole is even harder than it was on the other side. Possibly because elevation is going up. When I reached the pole, I was coming down from 6000 m to 5000 m. Now I am climbing up to 7500.

I keep getting rock walls in front of me

This is as bad as Wal

I really miss Leaping Mantis in this part of the road. At least Dancing Porcupine can point the rocket backwards and go up vertical surfaces. I'm using this feature so much in this terrain, I had to stop and refuel at some point.

Seen from a distance, the regular geometrical nature of the terrain becomes clear

Those last 30 km took forever. What keeps me going is knowing that gradually the terrain will become normal again.

Indeed, as I move away from the pole, I am already starting to get some stretches of relatively flat ground

And more relatively flat ground

Here the rover started sinking

But it's coming out again. Maybe it was a benign glitch that won't create problems?

Nope. Here comes the explosion. At least with all this slow going I am saving frequently

The bad terrain is ending

Here I am at 80° N. You can still see the lines of jagged peaks pointing radially to the pole, but the valleys in between are sort of manageable. They are actualy similar artifacts to those I found on Slate. In the distance you can see a sort of valley, the terrain issues end somewhere around there.

Edited February 20, 2023 by king of nowhere

[king of nowhere]

Part 9: From north to south pole

Exactly as the title says. The land is mostly highlands of average difficulty, with some stretch at lower elevation.

Spoiler

The biome that I will cross through until close to the south pole is called nockmaar foothills, and crew reports often remark on how flat and featureless they are. Which is quite inaccurate, because they are the highest elevation on the planet. They are a relatively flat plateau, though. elevation is mostly above 6000 m, with peaks above 8000.

Crossing this region is relatively easy, as there are no big changes in elevation. Dancing Porcupine struggles with those; it can keep going uphill as long as it has fuel, and it can pick up dangerous speeds downhill - it doesn't brake very well.

As I progressed, I learned to control speed downhill better. Or, rather, to just steer all the way and provoke an accident while the rover is still going slow enough to survive it.

I picked this specific longitude for the view of Priax in the sky

Priax is at Polta's L5 lagrangian point. I don't know how stable such a configuration would actually be over astronomical times.

Using the rockets to get out of one of the rare sinkholes of lower elevation

I planted a flag here because it was the higher elevation I reached

But it was soon surpassed by others. This point ended up as the highest one I touched. The highest point on Polta is 8800 m

Priax is moving higher and higher in the sky, but I can still see it from the cupola when the rover is going uphill, like here

And here we have Wal too. Tal is not visible

Progress is not terribly fast, but at least it's steady. I try to accelerate, but I rarely make it past 20 m/s before sliding on the irregular terrain. Polta is more difficult than it looks like. On the plus side, I rarely have to reload for damage; the new armor is almost unbreakable, especially at those low speeds, but the plane wheels in front are not doing their job. Hitting a bump can still result in breaking them, it's the most common cause of having to reload. I am almost tempted to let them break, then I remember that the rover wheels are even more frail. I should perhaps have used the heavier, sturdier model of plane wheels - Leaping Mantis does, and it can ram headfirst into near-vertical walls and survive - but they would have added significant mass.

There's no telling what average speed I could keep in those conditions. In my previous circumnavigations I could track time by the flags, but here I had to take frequent stops to recharge the battery, which does not last forever going uphill. More rarely, I had to take longer stops - a few days - to make more fuel.

Here I was cutting through a cliffside when the rover tumbled down. The high arch gave me time to extend the lower struts, though, so now Dancing Porcupine is practically indestructible. It survived

I stopped to put a flag on that hillside because, for a few km, I crossed another biome

Here I found this strange terrain artifact. It doesn't seem related to any specific coordinate. No accidents happened, though

I realized there are few views encompassing the greater landscape, so I'm trying to compensate with some

The crater in the picture reminds me to mention: Polta has relatively few craters, at least compared to Mun. You do occasionally find one across your path.

The more I think of it, the more Polta - with its somewhat irregular terrain and few mid-sized craters - remind me of Dres. I had a much harder time driving Dancing Porcupine on Dres, but was it because the terrain here is better, or just because I am more skilled and the gravity is higher? I have no plan to drive Dacing Porcupine on Dres, so I'll never know. I do have plans to drive Leaping Mantis on Dres, but it's a very different rover, and on low gravity worlds the reaction wheels make all the difference.

Ooops! I lost a lamp!

I got distracted and crashed headfirst into a boulder. Luckily the illuminator made contact first, and the way the game models collisions, this protected the rest of the rover. After checking that the last save was over 10 minutes earlier, I decided to keep the rover like this.

Here surviving a particularly fast collision. When fully deployed, the porcupine armor 2^TM is nigh-indestructible

I'm now close to the equator, so the rings make a vertical line in the sky

Priax is at my zenith, and difficult to include in a shot. The smaller bodies projecting dark spots on Urlum are flying boulders

A particularly steep passage

I am now closer to the south pole, the rings are extending behind me. The sun is providing less illumination, soon I'll ramp up light enahncement

And here we can appreciate the terrain artifacts as we're closing in on the south pole

I'm still at around 65° of latitude in the above picture, relatively far from the pole. The terrain artifacts become really bad around 10 degrees away, which translates to roughly 30 km on this planet. From the ground you barely notice them, unless you know what you're looking for. But seen from above, the terrain is already unmistakable.

Approaching 80° S, the grooves are getting deeper and more noticeable

And the terrain is getting more difficult, slowing my progress. But I only have to run 60 km like this

The bottom of the big crater seen a few pictures ago; it's incredibly flat, perhaps the flatter place on the whole planet, with only a few meters of difference in elevation between sides

Nice view of the polar crater

I take this chance to pick up some speed; but soon I have to slow down for the rim

Climbing up the rim. I had to extensively use the rockets, something I'm not too happy about because this biome has no ore

The polar terrain, in all its glory

And the actual south pole. This time there is no terrain glitch of any kind. I wonder why some poles have artifacts and some don't

Flag on the south pole

I don't know why the deltaV signal more than it did a few pics ago. I certainly did not refuel, ore concentration is too low for the small drills. Maybe that pic came from an aborted attempt where I crashed, and then when I reloaded I managed the climb at a lower cost. Or maybe it's just an irregularity because the rockets aren't perfectly lined up anymore; shortly after this I did some construction to fix them again.

Edited March 1, 2023 by king of nowhere

[king of nowhere]

Part 10: My rover will go on

Dancing Porcupine finishes the circumnavigation of Polta. I decide to also circumnavigate Priax.

Spoiler

After the south pole, Dancing Porcupine press on for the first flag.

At first, near the pole, the terrain is very difficult, and traveling is slow. But the crew is comforted by the though that for every meter of road, it will become easier.

Soon, paths of relatively flat terrain start to appear amid the spikes

Perhaps the best view of Wal so far. Why do I get so excited for seeing Wal as a dot in the sky, after I spent months circumnavigating it? No idea

While I can't wait to get out of this hard polar terrain, I will miss the sky view

Another terrain bug like I encountered in the previous chapter. Just like then, at first it looked like I was getting out safely, and then the rover suddenly exploded

After the polar terrain ends, this emisphere of Polta looks more like the beginning of the trip, with highlands and lowlands intermixed and frequent changes of elevation when crossing a plateau.

Here descending into a "valley". I miss Slate's water-carved topography

I'm trying light amplification at 10%. Looks like an excellent compromise between seeing things and keeping a good atmosphere

After a few hundred kilometers, I start to see the first flag

A lowland region; they are more grey than the plateaus, but they aren't substantially different in terms of driving experience

Crossing the 30 km mark

Finally, the flag!

Dancing Porcupine returned where it landed, completing the circumnavigation.

Also, since it was going downhill, I could not brake and I had to capsize it to stop. I almost crashed onto the flag itself, it would have been hilarious.

It took almost 90 days between the first and the last flag, but there's no way to assess average speed, because I had to frequently stop to recharge the batteries, and unfrequently to make new fuel. The ground contact bug made this operation even slower; without kerbalism, when the bug strikes the drills authomatically stop, and I have to exit time warp and manually reactivate them every time.

At this point, I consider whether going home or pressing forward. I already circumnavigated Slate and Polta, I decide that I want to finish the moons of Urlum; I only miss Priax and Tal, both are small. Priax is in the same orbit as Polta, so I'm going there first.

Leaving Polta

I went back to read my mission diary on the OPM grand tour. I did drive several hours on Polta despite not needing to, I liked it so much. Well, now I've seen enough Polta for a lifetime. It's really nice, but it does get old after a while.

Conversely, I hated Priax. Really hated it. Even more than Dres. Do I really want to commit to driving there? Well, I'll land, then I'll decide. It's small anyway, how long can it take for a circumnavigation?

Exiting Polta in a slightly higher orbit, so that Priax will overtake me eventually

Priax and Wal

About to land on Priax

The ground is extremely irregular, though I did remember it even worse

I'm landing straight on the edge of a crater. But the low gravity will help me

This image is just the perfect presentation for Priax

This happened two days ago, and by now I crossed 30 degrees, so I'm committed. Turned out, I hated Priax because it was almost impossible to move a rover on it, but with proper care - and helped by the rockets - it's not halfway so bad. But more Priax on the next update.

Edited March 9, 2023 by king of nowhere

[king of nowhere]

Part 11: Introducing Priax

Starting the circumnavigation of Priax, to the north pole.

Spoiler

Priax is a small moon, but not diminutive. With a nominal radius of 74 km, it is slightly bigger than Bop, and it has slightly more surface gravity.

The most striking feature of Priax, though, is the extreme irregularity of its surface. Priax is the body with the highest difference between highest and lowest point - the highest being at a record 30 km, and the lowest at 8 km. By sheer coincidence, the highest point is the bump just to the northeast of my landing spot, but I didn't realize it at the time and didn't mark it with a flag. What's the point of having a lowest point at 8 km? Wouldn't it be simpler to just make the radius 82 km and reduce the altitude of everything by 8 km? Meh. Most of the surface is between 20 and 25 km of elevation, so the actual diameter of the moon is closer to 95-100 km, and the gravity is slightly lower than on Bop, seeing as how you are farther from the "sea level" where you'd get the nominal value. The craters are very deep, with steep walls, providing the lower altitudes. Priax is the most irregular body among those in hydrostatic equilibrium .

I landed just on the aforementioned steep edge of a deep crater. I have to be careful to not slip down

When I previously landed on Priax, I didn't like it at all, but the main reason was lack of visibility. Indeed, this dark rock doesn't give much perspective when it's poorly lit, and it doesn't work well with light amplification. Fortunately, right now the sun is high overhead, and Priax is actually quite interesting. I like mountains.

The terrain is much similar to the one I found in the Wal circumnavigation, but this time the gravity is low, and it makes a big difference. I can't really pick up speed, unless I'm falling down a cliff. At low speed, I'm at no risk of damage. And going uphill is not a problem. It's not particularly difficult.

The main limitation to picking up speed is the terrain texture: I just can't stay in contact with the ground long enough to accelerate. I am making extensive use of the rockets to pick up speed. But I learned to not go much faster than 10 m/s, or I risk damage to the wheels - even though on other planets I can go a lot faster safely.

Incidentally, rereading the conditions for the elcano challenge, I see what I'm doing here - using the rockets mid-flight - is technically irregular. But I'm not doing it in large scale, just a few nudges here and there. Occasionally using the rockets downward to cushion a fall down a cliff.

Planting the first flag. I didn't want to stop the rover, so I just left while Dancing Porcupine kept driving

It eventually hit a bump and capsized while I was planting the flag, so it stopped anyway

Here I jumped inside a crater without realizing. And on Priax, they are deep. Had to use the rockets to slow down and survive

Between the terrain and gravity, I'm spending a lot of time airborne

There is a rugged beauty to Priax. When the place is lit up enough to see, once you accepted that your rover can't go fast, it's actually a great landscape.

In this case I used the rockets to nudge the rover away from the crater. Else I'd still be falling down it

As I move northward away from the equator, the light is less direct and the visibility problem starts to be seen.

A landscape in natural light. I can't see what's underneath me

Same in amplified light. I see a uniform color, and can't really understand the topography

To make things worse, Dancing Porcupine had one light pointing downward, useful to see where I'm landing after a jump... except it's the one that got destroyed while circumnavigating Polta, and that I didn't want to reload. Now I regret it.

Going down a particularly large crater. It's over 7 km deep compared to its borders.

Up again on the other side

Over a crest, then down and up again

Looking back at the whole sequence of down a crater - up over a crest - down again - up diagonally over a slope

Wheels sinking into the ground, again

On Priax I had a lot of instances of the ground contact bug. A lot more than on Polta. Worse, sometimes the bug manifests in the rover exploding mid-air as soon as it touches the ground, like in the sequence below.

Just touching the ground with the struts at 2 m/s

Sometimes I can avoid it by speeding up and slowing down time. Other times I have to resort to more extreme measures. Once I was forced to reload an older save because there was literally nothing I could do - move forward, fly with the rockets, extend the struts, time warp - without the rover suddenly exploding. The previous save was 5 minutes older, not a huge loss. Another time I had to take an 8 km suborbital jump to skip an area that was extremely bug-riddled, where Dancing Porcupine kept exploding for no reasons. That suborbital jump would be big enough to qualify as rule-breaking, except it was only motivated by bug-skipping.

I'm getting nearer to the pole, where any OPM planet has the radial grooves ground glitch.

An appreciation of the grooves

Priax is no exception, and you can see them furrows if you zoom out. But the ground is so rough, on the ground you see no difference over the rest of the moon. There are advantages in a chaotic terrain.

Near the pole, you can see the full ring system above Priax

Getting really close. Left of the navisphere you can see the hole in the ground where the pole is

This close to the pole, now the ground finally looks different

But it's only for a few kilometers, and the low gravity makes it more bearable

The pole. If you zoom in you can see Bob having planted a flag

Edited March 21, 2023 by king of nowhere

[king of nowhere]

Part 12: Craters

The circumnavigation continues, stumbling upon a truly gigantic crater and some smaller, but still noteworthy ones.

At over 12 km from top to bottom, this is by far the biggest cliff in the OPM system that I am aware of. I'd like to give it an impressive name, but I run out of them on Wal

Spoiler

As the title suggests, this second part of Priax circumnavigation focuses on some impressive craters. But first things first, I'm still at the pole.

Classic polar terrain artifacts, very sharp around the poles

On the plus side, Priax is small, it only takes a dozen km to go back to the usual terrain. Which is challenging nonetheless

There are way too many craters to try to dodge them. Especially since the terrain outside is not any better

Despite the low gravity, Dancing Porcupine can still pick up a lot of speed falling downhill. For that, I can still use the panic button and deploy the full armor

Those landing struts are very effective when tumbling uncontrollably down a crater. Although they have a nominal tolerance of 12 m/s, I used them at over 20 (vertical speed) with no damage.

And for every down, there is an up. I'm glad I have rockets, that slope is too much for the wheel power of Dancing Porcupine, even in low gravity

I'm glad I have rockets in general. Even though a more powerful rover could go uphill regardless, the problem with such steep slopes is that you can easily lose contact with the terrain, and fall down a long way before touching it again. This was part of the reason I found moving on Priax to be so frustrating the first time; I wanted to go uphill, and I kept falling more than I was climbing.

I skimmed a large crater. No, we haven't yet encountered the main craters of this chapter

In the map above, you can see a lot of big craters. And then there are smaller ones. Extend the line of the flags some 30 km to the south (I'm planting a flag every 20 km here, for reference) and you'll see a crater, fairly small on this scale, maybe a couple km across. But look at it, it does seem very sharp and definite. A lot sharper than other craters. That's because its walls are extra steep. And I stumbled down it unsuspectingly.

Crossed the last crest, and suddenly found myself midair. Well, except for the lack of air, of course

I fell and fell, and I still had enough horizontal speed that I kept outpacing the cliff. I gathered quite some speed by the time I was about to touch ground again. Enough speed to be lethal; as I often remarked, Dancing Porcupine can often survive up to 40 m/s on a regular capsize, but that's because it slides across the ground. A direct frontal impact is a lot more damaging, and 20 m/s are often enough to destroy something. And I'm already falling faster than that.

Nah, I'm exaggerating the danger. Dancing Porcupine do have rockets, after all. The whole "jump inside a crater and cushion the fall with a quick burst" was one of its selling points

Climbing up the other side, once more thanks to the rockets

During the whole Polta circumnavigation, I did regret not using the Leaping Mantis rover. It's a lot faster, and the active protection actually makes it more durable. I could have completed the circumnavigation in half the time. Here, though, I am so happy to have my old rover. Enhanced wheel power means nothing when you jump at the slightest bump, and enough reaction wheels to turn around and land wheel-first are overkill when the low gravity allows all the time to turn even a more sluggish rover. But the rockets, those are invaluable. I am glad I'm doing this circumnavigation, on an environment where Dancing Porcupine can actually shine; besides the rockets, the difficult terrain means I still get to use the Porcupine Armor occasionally - at speeds it can handle easily. It's a much better send-off than a mission for which I have more qualified machinery.

I am trying to not use the aforementioned rockets much, especially not airborne, since I read that rule. As a result, I am going a lot slower now. The huge delay since the previous update is partially due to that. Partially due to more craters. And partially due to the fact that I recently discovered they made another Monkey Island game, from the original creators no less. One year ago, no less, and I totally did not notice. That goddamn advertising algorithm keeps showing me trading apps with a "warning! 70+% of people who use this stuff actually loses money" in the fine print, and it never showed me the one thing that I would have bought without questions. But enough digressing.

Jumping out of that crater

And back to the usual terrain

And another update on the path taken. Priax looks like an apple that was exposed to a hailstorm

The real big crater, the mother of all craters, is waiting for me at the equator. But I still have some more road to go before it.

No craters, this counts as easy terrain on this moon

Lateral inclination + low gravity is the worst. At least on Wal I would not fly for half a minute if I slipped laterally

NOW we're getting there

This. This is the biggest crater I've ever seen

Actually, since I just mentioned Monkey Island, I should better say it's the second biggest crater I've ever seen.

But wait, you could say, there are a lot of bigger craters around. Kerbin has one that's clearly visible from orbit as a circular sea, Tylo has four major ones, Laythe even has a whole emisphere that's a giant crater. How is this the biggest?

But the thing is, those other craters are not something you actually see. They are too big. You drive around, then you have a mountain chain. You pass that, you climb down, then you have a plain. Then you keep going, and you find another mountain chain. And if you look from orbit, that's a crater rim, but it does not feel such. This crater, on the other hand, is just small enough that you can see it all in one go. Driving across it is a continuous experience, you never have a flat moment. Well, there's lots of flat ground in this crater, but it's all vertical.

Planting a flag in a very precarious position

Seen from the other side

One hour ago my elevation was over 20 km. I am following a straight southward path, and it misses the bottom of the crater, so this is the lowest I'll go. I'm at 14 km, and the crater keeps going down. It reaches 12 km in the deepest spot.

Incientally, that flag I just planted is the equator crossing. I'm officially past halfway. By coincidence, that flag only comes a few hundred meters before one of the regular 20 km flags, so the two appear overlapped and blurred in the map.

There is another large crater south of this one - in this view, south is left. But it's a lot less dramatic. We'll get there

The main feature of this crater, though is its southern wall. It starts at 12 km, though I never went below 14, and it goes up.

It keeps going up. I went up 3 km, and I'm still nowhere near halfway

Ok, try to get a scale like this. Dancing Porcupine is too small to be seen in this perspective; but when you just scroll away from your vessel, it stays in the middle of the screen. So the rover is in the middle of the screen. That is, in the middle of the cliff too, because the cliff fills the whole screen. I started climbing at 14 km, and now I am at 19 - I climbed up 5 km, while only going 9  km from the flags - and as you can see, after the flags I did not immediately begin to climb. The cliff ends somewhere between 24 and 25 km of elevation - 12 km of cliff, with an average inclination aove 45°.

This is the biggest cliff I know. In the stock game, there is the highest mountain of Eve, at 7500 m, from which you can fall down to the sea. It is massive. And this is almost twice as big.

Still in OPM, Wal has a huge mountain range on its equator that's up to 20 km high. But the surrounding land is around 4 km, so there's at most room for a 16 km cliff. And while there are several places that could certainly challenge the title, I didn't notice any with such a clear, uninterrupted path to the bottom. When I did climb that giant hole, it was "only" 8 km deep. Though the higher gravity and lack of rockets made it a lot more difficult, of course.

In the real solar system (and the rss mod) there is Verona Rupes on Miranda. A good competitor, but it stops at 10 km.

All in all, I'm calling this the bigger cliff, ever. But if you know of a bigger one, give me coordinates and I'll be happy to pay a visit.

Climbing up

Finally, getting out!

This is a pretty bug. Suddenly, for no apparent reason, every part started overheating, until the rover exploded. Reloading fixed the issue

And here we have the last crater, the one mentioned on the vast map

That one is certainly large, but it's not particularly deep or steep. No special difficulty going down.

This crater had a very large central peak, divided in three by some deep valleys

Getting out of that crater too

The terrain slopes downward afterwards

I'm stopping the chapter here, somewhere near 30° S at no particular marker, simply because I have more than enough material for a chapter. But also, that was the last really big crater until the south pole. Though smaller craters are not to be underestimated, as the first steep one showed.

Edited April 12, 2023 by king of nowhere

[king of nowhere]

Part 13: Ravines

The circumnavigation of Priax is eventually completed.

Spoiler

Even though the greatest obstacles were surpassed, Priax still has plenty. Here I got stuck into a trench.

 

I got free with a short rocket pulse

And here I'm going downhill a loooong way

I exploded a couple times, before resigning myself to braking

A nice view of the landscape

And a nice view of the sky

I was starting to be short in rocket fuel, and some biomes don't have refueling options. So here I'm making some more

By now I'm coming quite close to the south pole. This time, however, the terrain glitches are a lot less common. In the northern emisphere, I could already notice them at 60° N. Here I'm 80° S and still no sign of terrain artifacts.

No terrain artifacts yet

Here they are! Starting around 84° S, 10 km from the pole

Falling over one of those pyramids is death for the rover. Those points can get right between the armor and hit the weak central tank

More terrain artifacts. Now extra pointy

Still more terrain artifacts

Finally, the south pole. I'm trying to use low light amplification

It's not easy to tell, but Dancing Porcupine just exploded without reason

I got stuck into another bug trap. Not those where the wheels sink into the ground and I get the "no contact" message; I got plenty of those, and time warping to the maximum for a short moment generally fix those. This time if I move I explode, and if I time warp I also explode. I had a similar situation near the north pole, and I had to take a suborbital jump with the rockets. Here I had to do the same, skipping 3 km of terrain.

Landed back after the jump. The south pole is still visible; the while line is the polar "hole". I already spent all the new fuel I got

I'm back in the emisphere where Polta is visible

I'm within 100 km of the finish line!

Have to pass over this crest. One of the rare times I make deviations from a straight line, as going up and down takes extra time

Still running over the crest

The ridge region, seen from above

That was the last major crater on my path - though there are still many minor ones.

I'm now some 60 km from the end. I know the flag is in a biome without ore, so I must either replenish fuel before getting there, or I will have to wander some more afterwards to leave Priax. I decide, as I reach the top of the mountain at the end of the ridge (25 km altitude) to just perfom isru immediately.

Big mistake. With the tanks full, the rover is twice as heavy, but the wheels and reaction wheels did not gain any extra power. Dancing Porcupine had become a lot less responsive. Those last 60 km will be harder.

I already have direct line of sight to the final flag location, at 55 km away

Realize from this how tall is that mountain. Remember, Priax has a nominal radius of 87 km (100 km taking the elevation into account). A mountain is so tall, it is visible from half that distance. To make a comparison with our world, a mountain would have to be visible at 3500 km. Mount Everest would be visible everywhere from Iran to Japan. Or maybe one of the rocky mountains would be visible from Alaska to Colombia.

The last crater. It's small, but steep, and the full tank did not help. I exploded a few times going down

The first flag was on top of a  very high mountain, so the last leg involved lots and lots of climbing

The last 20 km or so were a continuous climb from 20 to 28 km altitude. I spent a fair bit of my newly-synthesised fuel for it

And here's the flag

SInce it was planted on a steep incline, as soon as it got back in physical range it started tumbling down. Not that it really matters.

And now let's move on, to new and wondrous adventures!

The Priax circumnavigation was slightly more than 600 km in lenght, though with all the ups and downs the actual distance traveled was likely 10 to 20% more. Hard to estimate how fast I was going on average; I had to spend a lot of time making fuel. In real life, it took two months, a bit more than Polta, but it's not a good indicator of anything; I am nowhere near consistent with how much time I devote to those missions.

For sure it was a hard planet. Not hard like Slate or Wal, but its own strange peculiar way of hard. And Dancing Porcupine turned out to be the perfect rover for it.

Next stop: Tal

Edited May 15, 2023 by king of nowhere

[king of nowhere]

Part 14: You must be this Tal to move forward

Dancing Porcupine travels to Tal, the sub-moon of Wal, to complete the circumnavigation of the moons of Urlum

Tal, in all its glossy charm

Spoiler

I loaded a lot of fuel before leaving Priax, because tiny Tal only has two biomes; assume that I get unlucky and none of them has fuel, I must have enough to leave and return to Priax.

Turns out, I didn't need to worry; the Priax-Tal transfer was a lot cheaper than I imagined, thanks to Urlum's low gravity.

Only 210 m/s to reach Wal, and 130 m/s for capture near Tal's orbit. It could have been even cheaper, had I wanted to wait for a proper transfer window

Wal on the left, Urlum on the right with Polta passing in front of it

IVA view of Wal. Even at this distance, the equatorial mountain range is clearly seen. Did I really go all the way around that?

Finally we see Tal, passing in front of Wal in this spectacular pic. It was actually visible also in the previous pic, but the color made them difficult to pick out

All bodies in the Urlum system in a single pick. Urlum, on the left, and Polta, starkingly contrasting the sky. Priax, to the right of Polta, is barely visible with its dark color. And of course, Wal and Tal

Arriving at Tal

Further insertion around Tal is also fairly cheap. Tal is a small body, with a radius of 22 km, one third of Minmus. However, it is a lot more dense, having almost the same surface gravity. A low orbit speed is around 100 m/s. It is only roughly spherical; I said that Priax is the most irregular body among those in hydrostatic equilibrium, but Tal is actually a serious contender for the title - depends on whether you consider it in hydrostatic equilibrium, and whether you're looking at big scale or large scale irregularities.

Descent

Perfect land___ back after the advertising

There, now, I said perfect landing

Edited May 15, 2023 by king of nowhere

[king of nowhere]

Part 15: The obstacle course

Beginning the Tal circumnavigation. Boulders create collisions, and avoiding them is hard in the low gravity.

Spoiler

The terrain of Tal is relatively flat, made of gentle rolling hills. I wouldn't call it spectacular, and I'm not fond of the yellow-ish color, but it is a nice place. You could do some pretty spectacular driving on it, if the gravity was higher. As it is, you are limited to about 10 m/s.

Since picking up speed is hard in the low gravity, I first tried to plant a flag with an EVA kerbal while the rover kept moving. As the images below show, it didn't work very well.

Here I missed the grabbing of the ladder, and Bill fell under the rover (you can see the helmet). He's the first victim of a car accident on Tal

Luckily kerbals are made of iron. Bill got up and is returning to the rover via jetpack... hey, does it look like Dancing Porcupine is heading straight towards that rock?

Ok. Next time I'll just stop the rover

Those boulders are quite annoying because they are just the right size to slip between the armor. Alas, it was designed to protect against impacts on a flat surface; also, to be as light as possible, because Dancing Porcupine is supposed to fly back to orbit with enough deltaV left to make an interplanetary trip and land on a Mun-sized body. I can't cover it completely. Also, the rover is moving just fast enough that hitting a boulder will explode the cupola, or the central tank. Meanwhile, in the low gravity it is very difficult to control the rover. In fact, the low gravity and the rolling hills means Dancing Porcupine keeps jumping, and it always risks landing on an obstacle.

Here Dancing Porcupine barely missed another stone

Fortunately, Dancing Porcupine has an ace up his sleeve, in that it has rockets. If I see I am about to fall just over a boulder, a quick push upwards will save the day. You can see I started driving with the rockets pointing downward by default. I am happy the new version of this rover can keep the rockets extended and still protected by the armor; the old model had to keep the engines retracted for them to be protected, and so extending them would cost precious time.

Technically this maneuver would be illegal, as the rules of the Elcano challenge state no propulsion while airborne, but that rule was meant to avoid speedrunning an Elcano on a minor planet by taking suborbital jumps. Occasionally extending a jump to save the rover from certain death is certainly within fair use.

In this valley there are boulders floating midair. Here Dancing Porcupine narrowly avoids a collision by passing underneath; an uncommon way to dodge a stationary boulder

More vistas of rolling hills

One such instance of using the rockets to avoid a stone

While the rolling hills seem random, when zooming outwards one can see there are some patterns. In particular, I am crossing Sigley region, the smaller of the two biomes of Tal, and I see the hills form a series of rings around its center.

And it looks like there's something in the center...

It's a hole! A Talhole!

I already did drive past it, and I didn't want to backtrack. But I decided I'd still visit the Talhole with alt-f12, and then reload.

[king of nowhere]

Part 16: Let me out of this Talhole!

Dancing Porcupine descends into the Talhole.

The mouth of the Talhole seen from inside. Unlike other holes, it's almost perfectly rectangular

Spoiler

As I mentioned, I didn't want to drive back a few kilometers, but I did want to jump into the Talhole, so I went there with alt-f12.

The outside of the Talhole

The Talhole is different from the other holes. For once, it's not at the poles. It's square instead of circular. And the rock inside has a different color. Finally, it has ground scatter objects inside. I wonder how many more of those holes are there. I mean, what are the odds I would pass close enough to this hole to see it if it was a unique feature?

Just on the rim

Vertigo!

Dancing Porcupine finally got stuck at 300 m of elevation, 3 km below the rim. Though it's stuck sideways, it will fall to 270 m. The bottom of the hole is slightly below 0, and it's the lowest point on Tal.

The rim seen from the bottom

Getting out was a bit complicated. The confines of the Talhole are very narrow, and I'm not perfectly aligned to go straight up; I would hit a wall, the rover would start tumbling, and then I would hit more walls and lose control and be forced to shut down the engines. On the plus side, the low gravity makes it easy to go up even with just the two back engines. After some trial and error I managed to get unstuck.

I only needed to go up a few hundred meters, now it's wide enough to pick some more speed

And then we went out to see the stars again

At this point I reloaded, so there would not be use of cheats in the actual Elcano challenge.

[king of nowhere]

Part 17: The north pole of Tal

Poles always have interesting terrain.

Spoiler

Reloading from the Talhole, back to the usual business.

I took this chance to display an internal overlay, a panorama, and some spectacle in the sky

Tal has several patterns in its hills. There is the one centered on the Talhole, but you can see from the image below that there are other concentric circles centered somewhere else; I haven't found any special feature on that alternate center.

Concentric hill patterns on Tal

As Dancing Porcupine keeps moving north, those gently rolling hills become sharper, more jagged.

Hill patterns on Tal, above 70° N

What were gentle slopes are now walls

Fortunately, the grooves are aligned with the pole. It's already hard to drive inside the ruts, but it would have been a lot harder if I had to drive across them.

The polar pattern, seen from above. You can see the polar terrain glitch as a small dark spot in the top right

Yep, driving around here was definitely difficult. But the low gravity helps. Polta was a lot worse

Finally, the pole

There's no flat ground around, I just stopped when I hit the bottom of the hole

The polar terrain, in its better rendition

The good thing about passing a pole is that you know the terrain will get better with time.

On this side of the pole, you get those sort of terracing. They are easy to drive on, as long as you can follow them.

Tal is lumpy, and Dancing Porcupine is now approaching the tallest part of the moonlet

Notice Priax on the left

I end this section with those couple spectacular sky views.

I didn't have much to say. After so many circumnavigations, there's not much more to remark.

[king of nowhere]

Part 18: The rest of Tal

The circumnavigation of Tal is completed.

The circle of flags as Dancing Porcupine is about to leave

Spoiler

One and a half months since last update. I really haven't progressed much lately; starting a new grand tour is more interesting than finishing a circumnavigation of a planet that turned out both longer and less interesting than anticipated. But eventually here I am.

After the north pole, the terrain goes back to normal.

The terrain from a distance shows this weird regular pattern

That is not apparent when seen from up close

Here we're near the equator

Ever since following the terrain pattern let me find the talhole, I'm regularly checking to see if I spot any regularity that could lead to anomalies. But I found none. I eve checked the lowest points on Priax and Wal wth cheats, just in case they hid some similar hole, but that's not the case. I was theorizing that perhaps there are similar holes in all OPM planets, because what are the odds I'd just randomly stumble onto the only one? But it really seems I did randomly stumble, yes.

Here I almost broke the rover on a stone. Fortunately I was going slow enough to avoid damage, courtesy of the low gravity

And here closer to the south pole. There are still regular patterns in the hills, but none have a giant hole in the middle

Approaching the south pole

The south pole has some cliffs intersecting

 I didn't want to use the rockets to climb. I find a place where the cliff is easier to pass

The south pole. No terrain glitches here

Moving away from the pole. Notice the line of spikes on the right

At 60° S, more weird patterns in the ground

Only a few kilometers from the first flag

First flag in sight

Circumnavigation complete

Tal is done. 200 km, at first it was exciting but eventually the low gravity and similar terrain smothered the excitement.

I started with the idea of circumnavigating one world with Dancing Porcupine, and I ended up doing five. Now it's time to go home. If I run more circumnavigations, I will want a more responsive rover.

[king of nowhere]

Part 19: Homecoming

While an Elcano challenge does not require returning the kerbals home, I did it anyway.

Rather, I returned to Minmus. From there it's just a matter of sending up some shuttle to carry back the crew

Spoiler

Dancing Porcupine doesn't have enough fuel for a direct trajectory, so I'll take a few gravity assists along the way. The natural target is Jool; I can use it to lower solar apoapsis and periapsis, resuling in cheaper transfer and cheaper injection. My plan is then to go for Duna, and refuel on Ike.

Tal to Jool. I probably could have saved something using Oberth effect properly instead of launching directly from Tal

Goodbye, Wal and Tal

Goodbye, Urlum

I use Jool to lower solar periapsis to Duna, so that injection would be cheaper.

Using Jool's gravity to get a good trajectory for Duna. 76 m/s is the plane change

Then a small syncronization change to meet Duna in two orbits. 1073 m/s of intercept speed, too fast to aerobrake but I have more than enough fuel

However, just as I'm about to arrive to Duna, I realize I'm in a transfer window with Kerbin, so I decide to use Duna's gravity to swing around it.

It's very expensive because Duna's gravity isn't much. I still have to spend 1000 m/s to get captured around Duna, then 700 m/s to leave for Kerbin - using Ike to turn the trajectory properly.

Yeah, probably not my smartest piece of navigation. Having infinite fuel from easy isru does that.

The trajectory around Duna and Ike

The burn at Ike periapsis

At this point I'm short on fuel. It would have been safer to land on Ike. Intercept speed on Kerbin is low. I use the gravity of Mun to reduce it further. I decide to get captured with an extremely high Kerbin apoapsis, and then raise periapsis at the level of Minmus. High apoapsis will make it cheaper to raise periapsis, and from such a high orbit intercept speed will be negligible; also, it will minimize the plane change. It's the best way to reach Minmus.

Of course, I have to reach Minmus because it's the only place I can land with the fuel I have left.

The Kerbin capture. 150 m/s at periapsis, plus a gravity assist from Mun, and 155 m/s to raise periapsis to Minmus

Syncronization to meet Minmus. As predicted, only 7 m/s of intercept and 28 m/s of plane change

7 m/s of intercept, but still 60 more for circularization

Turns out, I'm a bit short on fuel. I don't have enough to land. However, I do have a rover built for crash survivability. Just like on Ovok at the beginning of the trip, I am confident I can slow down enough to make a safe lithobraking at the end.

About to crash on a mountain side

Slowing down to 30 m/s

I know Dancing Porcupine can easily survive 30 m/s of horizontal speed. I keep 10 m/s to reduce vertical speed, so it will be the same as a road accident. That this rover can easily survive.

The first time, I broke a landing strut. Then I remembered I did add some on the bottom too. I haven't deployed them since Polta. In fact, I didn't have many chances to use the porcupine armor lately. I'm happy to have this last chance as a send-off to my old rover.

Dancing Porcupine hits the ground at 30 m/s and takes no damage

On Minmus I refueled, then I went to low Kerbin orbit. From there I need something else to pick up the crew; for all its versatility, this rover can't land on Kerbin, the terrier engines don't work near sea level.

Any vehicle would do to pick up the crew. And there creativity failed me. I wanted to make something cool, but could not think of anything special. So I just left them in orbit, assuming they will be picked up by something without me getting actively involved.

And that's the end of Dancing Porcupine. My dear old rover. I ended up driving it more than I imagined. It's slow and sluggish compared to other rovers, carrying around that giant fuel tank does have drawbacks. But having a single rover than can take off and go on another world is very cool. Not to mention the crash survivability. Who knows, maybe in another year or two I will bring it out of retirement again.