The most realistic Jool 5 (kerbalism, reasonable mass)

[king of nowhere]

Part 0: Inspiration, and setting the conditions

When I first declared my intention of running a grand tour with the kerbalism mod, some people told me it was impossible. I proceeded to build the DREAM BIG and do it, but some were not impressed; they rebuffed that the point of the mod is realism, and a 3000 ton ship is not realistic. While I stand by my reply that if we had the political will to sink a few thousand billion dollars into building that kind of ship we could do it, I have to concede that with a realistic industrial base sending thousands of tons to orbit is not feasible.

Now that I'm done with huge grand tours with super laggy ships and neverending eva trips to repair the hardware, I thought back about that exchange and decided to make something with it: a truly realistic Jool 5.

The main criteria I set is a limit on mass to LKO of 140 tons. Why exactly 140 tons, you may wonder? Because it's the payload of the Saturn V. So it's a mass that is realistic to launch. Of course, in KSP you can stretch your mass a lot further than you can in real life. But then, I'm not trying a moon landing, but a full Jool 5.

Some may not be impressed with a mass of 140 tons to orbit. After all, somebody managed to run a Jool 5 with less than 6 tons on the launchpad. But then, they didn't have to use kerbalism.

In addition to that main criteria, I have a bunch of additional constrains (spoilered for brevity)

Spoiler

- no ion engines. At the current tech level, using ion engines for human missions is not realistic.

- no nuclear engines. They were tested on the ground, but never flown in space.

- no nuclear electricity. It was never used on human missions, and radiations may be a concern.

- realistic duration. While taking a bunch of gravity assists and arriving to Jool in 15-20 years is cheaper than taking the direct route - even counting the extra food and water - sending two astronauts on a solo mission for 6-7 years is realistic (sort of); for 20 years, not much.

- realistic architecture. No kerbals landing on Tylo on an external seat. No planes with parts hanging in mid-air. No to a bunch of kerbalized stuff.

- realistic safety. While I have to accept some risk in the breaking of engines, all my vehicles need to have some extra fuel and some redundancies.

- realistic eva construction. While in orbit, swapping out a broken engine for a new one? If the ship was made to be serviced that way, sure, I can buy it. Manually detaching spent tanks to save on the mass of decouplers? Absolutely no way.

- realistic science. This is not the space race, where we go to plant a flag and show off out technological superiority on our rivals. This is a serious science mission. I have to make a serious attempt to gather plenty of science and sample, even though all that stuff is heavy. In particular, I'll give the Laythe plane 1 full ton of jet fuel for exploration purposes

- realistic radiation management. Yes, to land on Laythe I'll have to give Bill quite a strong dose. But aside from that, I'll try to keep radiation to a minimum

- realistic idiosyncratyc other stuff. There's some more instances where I did not take an easy solution because it felt wrong.

And this is why I am fairly confident in claiming this is probably the most realistic Jool 5 mission ever made. If we wanted to do it with current technology and capabilities, we'd do it somewhat like this one.

I only made one concession: I used an active radiation shield, a technology that does not yet exhist. The reason is mostly bug-related: without the active shield, the kerbals will pick up radiation damage. I can heal it with the radiation decontamination unit, but it consumes a lot of electricity, and the solar panels at Jool are not producing enough. So I have to set a cycle where the RDU is turned on and off repeatedly. And in those conditions, the game does not time warp well.

On second thought, I could have used more solar panels to keep the RDU always active even at Jool. But by the time I thought of it, I was already almost done.

Edited March 6, 2023 by king of nowhere

[Zozaf Kerman]

And why, exactly, haven’t you been hired for a big space agency yet?

[king of nowhere]

Part 1: Space industry in an Economic Downturn

Designing the components of this mission: habitation module Economic Downturn, taxi Right Answer, lander Seated Man, and plane Sole.

Economic Downturn, in all its stingy glory

140 tons look like a lot of mass. Even with the additional restriction, you can comfortably fit a Tylo lander in 10 tons, and a Laythe lander in 10 more tons, recyclable for other planets, and you can make a hab for 10 more tons. But then you have to have a taxi to carry those ships around Jool, and it needs fuel, and then you need to refuel those landers. And then you need something against the radiations. And you need a reentry pod for Kerbin reentry. And then you can't just get captured by a gravity assist, you need to raise your Jool periapsis outside of the radiation belt. And then you need to take all that stuff and fuel, and send it to Jool on a direct route.

I had to lower my safety standards a bit in this process, carrying less emergency fuel and less spare parts, to fit into the mass limit.

1.1) Economic Downturn habitation module

Spoiler

I will carry along two people in this mission, because making a mission with just one guy alone for 7 years is unreasonable, but with my mass limitation I cannot afford more than two.

Economic Downturn, schematics

The core habitation area is made by the cupola (necessary for the morale boost), the hitchhicker container (indispensable for the radiation decontamination unit and a few other morale boosts) and a lab, which I included because I felt I had to under the "realism" condition - though the fact that it has a high volume for the crew helped the decision. The reentry pod is disabled as habitat, because it's not covered from the solar storms. I used a separate landing module instead of strapping a heat shield under the hitchhicker container because I felt putting a big impassable heat shield between two livable zones was not realistic. Thinking again, I could have just swapped places between the lab and the container, and then it would have been fine. I did not put a probe core on the landing pod, an oversight that costed me dearly.

The whole thing has no radiation shielding; it would have added five tons, more than I could afford. Instead I used an active shield, only 2.5 tons, it's more effective than shielding while going interplanetary, it's completely useless in the radiation belts but I plan to skip those. No backup because my grand tours taught me, those shields are extremely reliable.

In retrospect, I should have used shielding. Yes, it's heavier, but lack of shielding means I was unable to take a Tylo gravity assist to return. Had to burn a lot more fuel, making up for the mass saved.

I would have liked to carry a lot more backups, but I could not afford the mass. Most of that stuff is low quality to save mass too, I'll have to run more frequent maintenance. But this ship is much smaller than my usual behemots, so it's not a big deal. A special mention for the engine, I used to carry a backup in the container, but I realized I can use the taxi's engine as backup, switching it between Economic Downturn and Right Answer as needed.

As for life support, I'm using one similar to the ISS: food is stored as it is, water is used to get oxygen. Sabatier reaction recyles the CO₂. All in all, I get 12 years of life support with 1.25 tons of consumables.

I was really uncertain on the name. On one hand, I wanted something to emphasize how this is the result of a realistic budget forbidding another thousand-tons monstruosity, so I considered everything from Budget Cuts to Financial Crysis. On the other hand, since my first megaship was dubbed DREAM BIG, I was tempted to call this one WAKE UP. I liked both names, but I had to pick.

The above pic does not include the Kerbin ejection module, to propel everything towards Jool. I wanted to focus on the hab, there's not much of interest about a couple of boosters. Though those boosters alone are not enough to reach Jool, some of Economic Downturn fuel will have to be spent along the way.

1.2) Seated Man Tylo/Bop/Pol lander

Spoiler

Once established that I cannot just send down a man in an external seat, using the smallest crew cabin is the best that can be done. No shielding or anything.

Seated Man, schematics

Significant mass savings were achieved when I realized I could skip on a powerful first stage engine by making the second stage such that its engines could also propel the first stage. Also, by removing the landing legs and using quadruple fuel tanks in their stead.

On paper, it's got a lot more deltaV than it needs. Some of that is extra - any realistic mission has some spare fuel for emergencies. But most of it is practical. First, if the reaction wheel of the pod breaks, I will need to take a spare one, for increased mass. Second, I will get a sample from Tylo, and under kerbalism those samples have mass. Third, The last stage has really low thrust, so I will have to either keep the second stage and burn through the third stage fuel, or to ascend with a high apoapsis to have the time to circularize. Either way, it's going to be more expensive. But worth for having a Bop-Pol lander of less than one ton.

My normal kerbalism policy involves redundant everything, but I could not afford a redundant engine with the mass constrains. I'll just have to hope it doesn't break. I don't see real space agencies putting spare engines on rockets, so I assume engine failure is actually a lot less likely than it is on this mod.

I gave it its name because, seen frontally, the lower taks can be seen as legs and knees, the middle tank as the torso, and the pod as the head. Also, I had no better ideas.

1.3) Sole (the fish, not the body part) plane

Spoiler

This time I'm using a hybrid plane-rocket model. I considered a rapier-based design, but quickly discarded it; the rapier alone weights two tons, it's too heavy to be worth its benefit. And I can't recycle it for landing on Vall, as I'm doing with the rocket part of this plane. After strapping some landing legs on it, of course.

Sole, schematics

My usual choice here is propeller plane, fueled by RTGs or by a fuel cell. But I know an electric plane would not really be feasible in reality, they are in ksp only because propellers consume much less electricity than they should. So I was forced to use a jet engine. I'm glad I could use the panther, it's the only model that is light enough to be practical, and powerful enough to allow Sole to take off from water, a necessity for a thorough Laythe exploration.

Here I really paid a tribute to science, both in carrying a lot of jet fuel to fly around, and in using an atmospheric analyzer - which kerbalism makes a lot heavier than the stock game. It also produces a lot of samples, hence the container.

I skipped a vertical fin. Reaction wheels can take care of that, and it saves some weight.

The hardest decision was removing all the solar panels. It's not much the weight, but the aerodinamics that was really complicating things. But Sole has enough battery to carry on a long time, and the jet engine makes a lot of electricity.

I called it Sole, as the fish, because it's very flat.

1.4) Right Answer taxi

Spoiler

The taxi is the thing that carries the landers from the mothership to the planet. Normally I put some luxury on them, but this time I really could not afford the mass, so it's little more than a fuel tank.

Right Answer, schematics

To save mass on the landers, I skipped life support. Sure, they have one scrubber, if that fails they have enough air to complete their mission. But for long term transfer I need some air recycling, and I put it on the taxi. I also put here the extra food. I added two ant engines as backups in case the terrier fails, it's going to be very uncomfortable to try and do anything with them, but it's better than failing.

I did loathe using the heavier retractable solar panels - 200 kg, the non-retractable were only 70 kg - but I needed the thermal resistance to aerobrake on Laythe.

Lack of communication with the ksc was a constant source of problems; I would have put a relay antenna on Economic Downturn to ensure having signal on the probe, but guess what? Too heavy. I had to manage with limited probe control. I gotta say, when I could not throttle the engines those two ants were really useful for docking maneuvers.

I gave it its name because, seen from above, it looked like a circle barred by a cross. Like in a test, when you have multiple answers and you cross the right one. Sure, I could have called it Wrong Answer because there's no guarantee you're getting the proper solution, but I decided to be optimistic.

The whole mission ended up costing 320k, including the launcher. A far cry from my previous projects.

On 2/15/2023 at 12:58 AM, Zozaf Kerman said:

And why, exactly, haven’t you been hired for a big space agency yet?

I can't tell if you're complimenting me or you're being sarcastic.

Either way, space agencies do not exactly pop up like mushrooms around, nor are they hiring chemists all the time.

Edited March 4, 2023 by king of nowhere

[Zozaf Kerman]

Complimenting, sorry if it was unclear. I was just mentioning how well thought of this mission was. 

[king of nowhere]

Part 2: Traveling to Jool - in third class

Economic Downturn is launched and takes a direct route to Jool, using Mun for a small gravity assist. It arrives at Jool 3 years later, gets gravity captured at Tylo using a careful trajectory to avoid the radiations, then raises periapsis outside of the death zone.

Here swapping out a broken solar panel on Right Answer for the spare I had

2.1) Launcher? The mission conditions said nothing about a launcher

Spoiler

I put a lot of thought on how to keep realistic constraints on the mission, starting from the mass to orbit. But I said nothing about the launcher. And in this case I'm not caring about realism.

I just put a bigger rocket under the fully assembled Economic Downturn

The thing is, it would be realistic to make separate launches for the various parts, instead of sending them in that top-draggy stack. Or maybe to pile them together inside a fairing, like the Moon missions did. But making some simple launches and rendez-vous in LKO is something I've done to death (over 100 times for my caveman Jool 5 alone) and I have no interest in repeating them. So I just made the rocket that would minimize the boring part.

As crew I choose Bill and Bob. Bill because I need an engineer to repair stuff, and Bob because it's a science mission. No pilots, they are replaced by computers.

Booster separation. Some weird heating artifacts I've only seen with kerbalism

Economic Downturn in orbit, ready to go

As you can see, I stuck to 140.00 tons exactly; I already cut into all the safety measures deeper than I'd like, I want to use all the mass I can.

A few things to notice:

- There is some room for additional liquid fuel. That's because the Sabatier process makes some as a byproduct, and I wanted to recycle it in full (turned out I was overly optimistic, I got like 50 kg during the whole trip to Jool and ended up discarding two empty tanks on Sole)

- I emptied most monopropellant tanks, but I still carry some. It is needed to use the jetpack in spacewalk, which I need to repair the ship

- I did start with the septic tanks full of waste water, to get some extra water for the mission without needing an extra water tank.

- The frontal nose cone of Sole is currently attached to a drop tank to leave the docking port free. It will be moved to the correct place at Laythe

Now I'm ready for the real mission.

2.2) The direct way

Spoiler

As I already mentioned, I can't afford the time for a protracted chain of gravity assists, so I have to take the direct way, which costs some 2000 m/s. Additionally, not shown, an 80 m/s plane change somewhere around Dres.

I also have to do it fast, part of the conditions are that I'm not taking multiple passages in the Van Allen belts (though I suppose here they'd call them the Van Kerman belts). Hence those two poodle engines on the boosters; I'd have skipped them gladly for 5 more tons of fuel, but alas, I need a decent thrust.

Finally, I decide to use a gravity assist from Mun. It doesn't do much, it saves some 70 m/s, but it's better than nothing.

The ejection from Kerbin and Mun assist

The deltaV numbers on the staging panel are skewed because this screenshot is for a first attempt, which was unsuccessful. Turned out, the second time I did this mission I did not take any screenshot of the planned maneuvers.

Anyway, I tried and I discovered that I simply cannot make the long burn with enough precision to take that gravity assist. So I compromised a bit and made an apoapsis raising first. But only one. So the crew will make two short passages through the radiation belts, they are still fine. The crew will only take a few % radiation damage.

After raising apoapsis by 870 m/s in a single maneuver, this is the new plan

This time the ejection burn is short enough to be accurate, Economic Downturn takes the gravity assist properly and is en route to Jool with minimal need for corrections.

The ejection burn, still with the old version of the ship - but it's the only pic I have with the boosters being used

That old version looks so ugly now that I improved it. The large relay antennas eat up almost 3 tons by themselves, and the Tylo lander (which was called BigMac at the time, as its three layers bear some similitude with a cheeseburger) is weighted by those landing legs and heavy first stage engine. As a result, it had a lot less deltaV - although its mission didn't fail for that reason; we'll get to it.

The final version of Economic Downturn has 1960 m/s in the boosters, which is just enough for the ejection burn - nominally it should have been 1930, but 30 m/s more of cosine losses are quite a good result with low thrust.

After one year, the 80 m/s plane change; Economic Downturn started using its own fuel for that. I also run the first maintenance at that time. The trip was mostly uneventful, I broke the solar panel shown in the first image but nothing else. I still had to use the radiation decontamination unit (RDU) a bit, because despite the shielding my crew is still taking some small radiation damage. And there is not enough electricity to keep it active constantly, so I have to set up the kerbalism setting to activate the RDU when the battery is full, and shut it down when it is low, and those kind of authomated settings don't work at time warp above x1000, so it was quite slow. But thanks to the active shield, I only had to activate the RDU for 20 days or so. This is the first and foremost reason I used an active shield instead of shielding - it would have required more use of the RDU.

Time for the arrival procedures.

Injection into the Jool system

Capture at Jool by gravity assist is relatively easy, in this case it is complicated by the radiation, which my ship cannot withstand. I had to carefully set up my trajectory so that I would meet Tylo when it's closer to the sun, and therefore outside - just barely - of the death zone.

The ensuing trajectory results in an elliptic Jool orbit, which requires some periapsis raising to keep out of the death zone. I also had to pick a good compromise with high apoapsis and orbital time. On one hand, a higher apoapsis will result in a cheaper burn to raise periapsis. It is also necessary to reunite the Tylo lander with the mothership. But too slow an orbital time results in more time to rejoin the landers with the mothership, and food supplies are limited. 230 Mm looked like a good compromise.

Detaching Seated Man with Right Answer

Finally, since I am already thouching Tylo's orbit in a low energy trajectory at a time when it's outside the radiation belt, I take this chance as the best time to send the Tylo lander. It's cheaper this way, it's less mass for the Jool periapsis raising. I detach the lander one week before Tylo encounter, just as I'm entering the Jool magnetosphere which protects from solar storms, and set course for a low periapsis.

While Economic Downturn successfully completed insertion into its Jool parking orbit, Seated Man's landing on Tylo will be covered in the next chapter.

Edited March 6, 2023 by king of nowhere

[king of nowhere]

Part 3: Tylo is always Tylo

Seated Man lands on Tylo and returns.

Economic Downturn faces a most insidious challenge in the solar occultation by Jool.

3.1) Tylo landing

Spoiler

Right answer has 1750 m/s while carrying Seated Man, and most of that will be needed to circularize around Tylo. Of course, after the landing Seated Man will be a lot lighter, increasing the deltaV.

Injection on Tylo. 250 m/s for capture and 800 m/s for circularization, done in a single maneuver before tylo can get back inside the radiation belt

In low Tylo orbit. Right Answer used up most of its fuel for this part. Irradiation of the crew is minimal. 50 days worth of life support

Electricity is at a premium. I was very careful with batteries and solar panels: the batteries recharge on the day side, and they last just long enough to survive the night. I would have strapped the magnetometer on Right Answer for more science, but it cannot afford the 0.05 Ec/s that experiment drains. Data transmission is also suspended.

Seated Man starts descent

Now, the very most efficient way to land on Tylo would be to lower orbit to the exact altitude of the highest mountain on the equator, and start the braking burn - keeping always the same altitude - to arrive perfectly still on its top.

I could probably say something on landing on the mountaintop not being very realistic, but ultimately I never tried that maneuver because it requires a lot more trial and error than I'm willing to make - or it requires using mods to time it just right, which is also something I don't fancy doing. And for a minimal gain. Yes, here I am using 3 solar panels instead of 4 to save 17 kg, but I still must draw the line somewhere.

90 seconds later, about to land

Landed on Tylo

I was fairly efficient during descent, and saved 120 m/s. I tested the lander assuming the first stage would be completely spent during this phase.

Here I grab a stone for return to Kerbin. This is a realistic mission, collecting samples is important

Still, Tylo is the target where I will perform less science; only one sample, plus one surface feature.

The thing is, trying to land on a biome boundary on Tylo is a lot more difficult. But anyway, Tylo is the least interesting target from a human exploration perspective. Laythe has a very interesting climate and could host life deep in the ocean, protected from surface radiations, so I allocated a lot of resources to Laythe. Vall has an interesting geology, though radiations prevent an extended stay. Bop and Pol are potential mining targets, due to their low gravity and low radiations. But Tylo? It is great for gravity assists, but it is too expensive to land and too irradiated to be worth exploiting for resources. And it's still a barren rock, not much different from thousands of other barren rocks except for being significantly bigger, so it doesn't have a huge science value either.

Anyway, as soon as Right Answer was passing overhead, I went back to orbit.

Second stage ascending. I forgot to remove the ladder, but it's only 5 kg

Discarding the second stage, after draining some of the third stage

Remember, the third stage has very low thrust. I wanted to raise apoapsis a bit more before going with it alone.

Made it to orbit, with 23 m/s left

That was fairly inefficient. I did test this lander with an extra reaction wheel (in case the one in the pod broke and I had to strap on an additional one) and no fuel in the first stage, and it still reached orbit. I suppose I should have gone for a higher apoapsis first, and then ejected the second stage as soon as possible. Anyway, I'm in orbit and I can live with it.

Spending those 23 m/s to get closer to Right Answer resulted in only 20 m/s intercept speed.

Rendez-vous with Right Answer. From this angle you can appreciate its name

Right answer has no signal to the ksc, but it's still got partial probe control, so it's manageable. I can point it towards the target docking port thanks to the advanced probe core, and I can use the engines at full, though I cannot throttle them. In this case, the small backup engines proved invalubale; the terrier is too powerful to make fine docking maneuvers if I can't throttle it down; two ants give a gentle enough push that I can dock easily with them. From a realism perspective, it wouldn't be a problem for Bill to take remote control of the probe from 200 meters away. It would be even less of a problem for the smart people in the space center to figure out a slightly different trajectory resulting in rendez-vous somewhere where the taxi has signal.

Docked again. Now I have 1800 m/s deltaV to return to Economic Downturn

First step is to get away from Tylo before it plunges into the radiation belt. 800 m/s, plus a small periapsis raising later on, will put me on a safe orbit

Here the pics I took with the trajectory get quite confusing, especially because Economic Downturn is still not on its final orbit. Still, you should see that Right Answer parking orbit touches Economic Downturn projected orbit, so it will be easy to syncronize for a passage once there. And this far from Jool, raising periapsis is fairly cheap.

30 days later, with 500 m/s left, Right Answer returns to Economic Downturn

At this point I want to heal Bill of radiations before going for Laythe. He's only got 5% radiation or so, but he'll have to take a long plunge inside the death zone, I want to give him the best chance.

This involved some 40 days spent at x1000 time warp with the RDU going on an off. I really should have used more solar panels. But they are 300 kg each!

Just a nice pic of Laythe passing in front of Jool

3.2) The long night

Spoiler

I'm not used to saving mass.

I can manage if I have to - doing a caveman proves that much. And I'm not wasteful; even my most gargantuan spaceships, to guarantee life support to 9 kerbals for decades they need a hundred tons of habitation modules, and they need tens of tons of water, and there's really nothing that can be done to save that mass, and then there is the rest of the payload, and to move that I really need a few thousand tons, even if I'm trying to be conservative.

But even though I'm not wasteful, I got used to travel in luxury. Because once I have to have hundreds and hundreds of tons of payload, then there's no point in saving on the small things. Should I put in an extra solar panel, just to be sure I won't have issues with electricity? Sure. More reaction wheels, for more comfortable docking? Go ahead. An extra battery? Make it two! Because all that stuff is very light compared to everything else that I'm already carrying. When you have 1500 tons of dry mass, adding 10 tons in stuff that makes my life easier doesn't have any meaningful impact on deltaV. So I'm used to not having to worry about stuff that can easily be solved by adding a little mass, like reaction wheel, communication, and electricity.

Yeah, about electricity.

I mentioned that the first time I sent this mission, it failed. It did not fail because my ship was heavier; it may or may not have been able to return to Kerbin. It did not fail because it lacked a reentry pod; though that was certainly a grave overlook on my part, and a rescue mission would have to count on the 140 ton to orbit limit, making me fail.

No, I failed for electricity. Specifically, for not thinking that even though my orbit is high, Jool is still covering the sun for a long amount of time.

Kerbol disappears behind Jool. As you realize the battery won't last through the night, you may now scream in terror. Maybe those screams will keep you warm in the frigid joolian night

As you can see from above, I've shut down everything (except the TV, but its consumption is negligible), and still I use up 1 Ec/s for heating alone. Battery will be drained in less than half an hour. I already complained several times about how, for all its pretence on realism, kerbalism does a terrible job of simulating heating and cooling - because even a large spacecraft, that should have quite a lot of thermal inertia, will freeze in minutes as soon as the sun sets. That's exactly what made my first mission fail. Solar occultation lasts 150 minutes, and my crew was already dead after one hour, and there was nothing I could do to save them.

Wait, I could have picked up an orbital inclination, just one degree would have been enough to still see the sun, and it would have had a negligible cost. Ok, but the mission would have still failed for lack of reentry pod, so it's good that I didn't think of it.

Anyway, if I need 1 Ec/s for two and a half hour, when I remade Economic Downturn I was about to add enough battery for 10000 units of charge. Then I thought better, and instead of adding 600 kg of battery I added only 100 kg of H₂/O₂ fuel cells. I already have an hydrogen-producing apparatus and hydrogen tank for the Sabatier reaction, and the water made as byproduct is recycled.

Only problem is, normally Sabatier reaction uses up all the hydrogen I produce. I have to remember to shut it down before passing behind Jool, to build up a hydrogen stock. And it takes a while to build up that stock. So I faced this long night with half the hydrogen I should have. That hydrogen lasted for 90 minutes, then the crew still died of cold half an hour before seeing the new sun.

I solved the issue by letting the crew start to freeze, and then activate the fuel cells. But only enough for them to warm up a bit, before shutting them down again to save hydrogen. The crew was freezing again, and then I restarted the fuel cells. Rinse and repeat, except without rinsing because there's no heating and I can't afford to duck my crew in cold water.

After150 endless minutes, the sun appears again behind Jool. The hydrogen run out, the crew is experiencing mild hypothermia, but they live. They live!

In any case, I've shown that the system works, if only I remember to refill hydrogen in time.

The second night I did, and I had no problem. The third night I didn't, and I was exploring Laythe, and reloading back to a few days before would lose many hours of flying; so I basically cheated. After parking my plane, I time warped x100000. At that speed, the game does not realize Economic Downturn is passing behind Jool and there are no electricity shortages.

I don't have problems doing that, because in a realistic mission they would not have forgot to refill the hydrogen tank.

Edited March 6, 2023 by king of nowhere

[king of nowhere]

Part 4: Do we feel lonely in the universe?

Laythe is the perfect science target. First, because of its unique enviroment and potential for life. Second, because its oxygen atmosphere protects from radiations and allows use of jet engines. This unique combination gives a kerbonaut the reason to fly halfway around the planet to gather different samples, and the means to do it at a reasonable cost.

4.1) Minimizing fuel spent and radiations acquired

Spoiler

With Bill fully healed, it's time to send him to Laythe, and then to Vall.

I would like to alternate between pilots, but Bill is the only one that can fix a broken engine, he has to go.

Sole paired with Right Answer. There are also the landing legs needed for Vall, temporarily attached on Right Answer

A nice Hohmann transfer from apoapsis ensures the best compromise between a mild intercept deltaV and a quick pass amid the radiation belt

Aerobraking

I was faced with a conundrum regarding aerobraking. On one hand I could aerobrake the spaceship whole, getting captured by Laythe. Then Sole would take a final plunge in the atmosphere. The downside is that Sole would have to take one orbit around Laythe, exposed to deadly radiations. Not ideal. On the other hand I could aerobrake only Sole, to ensure it would immediately reach the ground, but then I would have to rocket capture Right Answer, and fuel is precious. I could also separate Sole and Right Answer and ensuring they hit Laythe at different times, but to make such a maneuver cheaply I'd have to separate a few hours before hitting the atmosphere, Sole has no solar panels of its own, and I'd like to conserve its electricity.

I opted for something more showy: aerobrake both vehicles together, and separate them while in the atmosphere. Point the plane with the wings to offer maximum resistance. This way, if I pick the right altitude (took a bit of trial and error) Sole will stay in the atmosphere, minimizing its radiation exposure, and Right Answer will brake enough to get captured, but will stay in orbit. The two vehicles will stay close enough to not get authomatically deleted by the physics engine.

Here just after detaching, you can still see Right Answer in the distance

What about realism? Undocking while aerobraking doesn't seem very realistic. Ok, but I'm only doing it because of the physics engine limitation. In reality there would be no issue with having two objects in the atmosphere simultaneously, and so Sole could undock a few minutes before reentry.

Once more, thanks to the AntennaSleep mod for giving the option to retract antennas during aerobraking and have them pop up again afterwards. I tried to avoid using mods in this mission, except for kerbalism, because I wanted a mission as stock as possible - to the point of using those cumbersome lateral tanks for the jet fuel instead of using a fuselage tank with fuel switch. AntennaSleep is the only exception, because it's simple, useful, and it adds to realism. Without that very simple mod, aerobraking a probe with a retractable antenna would not be possible.

Sole aerobraking, and almost melting some components

Finally it's down to normal flight speeds, while Right Answer remains orbiting with a 900 km apoapsis

Preparing to land on a shore

Near perfect landing!

Sole is kinda hard to land; I crash it a bit over 50% of times. Probably because I'm not used to a jet engines; I always used propellers in the past, and by choosing an angle of attack you can keep a propeller plane at a fixed speed, proper for landing. With a jet engine it's more complicated, and to save fuel I tend to land with the engine shut down.

I assume in reality they'd train the pilot better.

4.2) We will not cease from Laythe exploration. And the end of all our exploring will be to arrive where we started. And carry back 200 kg of samples

Spoiler

After landing, I moved the extra nose cone to the front of the plane.

Battery status; it was half spent to start with because I passed behind Jool, but the consumption is extremely low

Then, with Sole in a stable situation, I went back to Right Answer. I have to finish circularizing its orbit, which I did with another aerobraking passage. Then a small apoapsis raising left it in a nice 65*53 km orbit almost for free.

Right Answer in its final orbit, with most of its fuel spared. It will be needed for Vall

Then I look around and plan a course for Sole. There are 5 major biomes on Laythe: shores, dunes and peaks, which are land biomes. Shallows and sagen sea, which are water biomes. Those are scattered around the planet, and I want to get them all. I notice that directy north of me, some 300 km away, is crescent lagoon, a small localized biome. I'm not sure I have enough fuel, but I try to go for it.

Taking off

Sole doesn't take off easily; its backward wheels are too far behind, so it can't lift its nose. This is actually intentional, it makes the plane more stable on the ground. As for taking off, I need to find some bump on the terrain. Which is not difficult at all on Laythe. Once it takes a bump, Sole can turn up very fast.

Splash-landed

Here on my first stop, on Sagen sea, getting more samples.

I said I was glad for the panther engine, and the reason is the afterburn function. I discovered in early testing that I need an extra kick to take off from water, and the panther - with its extra power at the cost of more fuel - is exactly the solution to my problem. As for fuel consumption, it only uses the afterburner for a few tens of seconds, so it's limited. Especially compared to other solutions I may have enacted to take off from water.

Sole activates the afterburner...

... And soars out of the water like its namesake fish! Or at least, it soars like a sole would soar if it had a jet engine strapped to its butt. No analogy is perfect

After a stretch of sea, another island

Stopping to collect samples, we are real astronauts

I'm starting to run low on fuel. Those are only the drop tanks, but then I have to go back to the equator, and I need to fly to high altitude before I can use the rocket to return to orbit

But I landed on the last crest (peaks biome). In front of me is crescent bay. And to save fuel, I'll just fall there by gravity. Took a few tries before I could manage it without crashing the plane

That final shore was steep enough that I could take off again, without even using the engine

Arrived at crescent lagoon

And so I took samples from six different biomes. I'm running out of space in my sample collector, atmospheric science takes up a lot of space.

Now, since I don't want to enter orbit with a high inclination, I have to return to the equator. I squeeze the last bit of fuel from the drop tanks to take off from water and land on the shore, where I remove them. It took me 500 kg of fuel to get here, and I only have 500 kg more left, and I need to keep some for the orbital launch. But going here I landed many times, and taking off is expensive, especially from water. And there are those draggy drop tanks, now the plane is much more streamlined. I hope this will be enough to save fuel, else I will have to reload several hours back.

Removing the drop tanks. I said no to using eva construction in place of staging, but this is a simple operation to be done on the ground with no hurry

Back to the starting flag, still 170 kg of fuel left

In my tests I used the afterburner to fly up to 20 km altitude before stage separation, and I used up 300 kg of fuel. But I was starting from water, this time I'm on the ground at some altitude, it will be cheaper to take off. And even if I shut down the jet engine a bit earlier, the rocket should still propel me to orbit.

However, I have to wait. Laythe and Vall are not aligned for a transfer. And since in orbit I'd be blasted with deadly radiations while here on the surface I'm only subject to mild levels, I won't leave Laythe until the last moment.

The position of Laythe and Vall. I already planned the maneuver of Right Answer to know the right time to leave Laythe

This, unfortunately, brought an unexpected problem: electricity (again). I didn't put solar panels on Sole because I could not afford the mass and the aerodinamics. I relied on the jet engine to recharge the battery. However, I already spent all the jet fuel, and now I have to wait 3 days, and the battery doesn't last that long.

Bill out of battery on Laythe. Also, 26% radiation damage taken so far

But fortunately, Bill is at Laythe's equator. It's cold for human standards, but it's the "I need to put on a coat" kind of cold, not the "atmospheric nitrogen is condensing and falling as rain" kind of cold. And there's no need for an air filter, because the air is breathable. In short, it's the kind of environment where a human with heavy clothing and some emergency rations can survive for a few days without electricity or fire.

I suppose in a realistic mission they would have thought about this before sending Bill on a distant biome consuming all its fuel.

4.3) If a sole flies out of water and nobody is watching, does it fall back?

Spoiler

A few days later, it's time to go and Bill is still fine. A lot less cold than he was on Economic Downturn during the long night.

The normal engine functionality carries Sole up to 7000 m, then it's afterburner

At 16 km fuel is running out. Ideally I would have reached 20, but this is good enough

The jet engine and wings are jettisoned (on the top left of the screen) and Sole now ascends as a rocket

Laythe's atmosphere is tricky, but nothing I didn't test thoroughly

Coming up to intercept Right Answer

I missed the first intercept, had to maneuver to get another one next orbit

Good thing my ejection burn was planned for the next orbit; I knew catching the taxi straight out of the atmosphere would have been unlikely, requiring more timing than I can normally manage. Especially because the plane ascent is difficult to reproduce exactly. The price is spending an extra 30 minutes in the radiations, hopefully it shouldn't do a big difference.

I wonder what I would have done had the engine broken during ascent; I didn't have a plan for it. I'd have probably reloaded, to not waste all the effort, but I would have specified I needed to do it in the mission report.

Edited February 17, 2023 by king of nowhere

[king of nowhere]

Part 5: The most beautiful snowball in the Kerbol system

Sole - what's left of it - goes to land on Vall, then returns to Economic Downturn just before Bill takes an excessive dose of radiations.

5.1) A simple Hohmann transfer

Spoiler

I'm going to Vall on a normal, cheap trajectory because I can't afford the extra fuel for anything faster. In my previous experience, I should have enough time before Bill dies of radiation exposure.

900 m/s and two days needed

There were 2 life support units on Right Answer, now only one? What happened to the other?

It probably broke during aerobraking while I wasn't watching. Anyway, I had 2 for a reason, though this is not how I imagined I'd lose one.

Mounting the landing legs on Sole

I imagine that if the fuel tank already had holes in the right places to install the landing legs, it would be possible for an astronaut to install them in a reasonable amount of time. By "reasonable", I mean "fast enough to not be fried by the radiations". I didn't think on this detail when planning the mission.

Approaching Vall. Also, appreciating the X shape of Right Answer

50% radiation damage reached

At Vall

5.2) A simple landing

Spoiler

Landing on Vall is simple. Sole is a bit oversized for it; I would have made it smaller, but those size 1 fuel tanks go in 500 kg units, and removing one unit would cut too deeply in the deltaV. Anyway, given the mass of samples I'm carrying, I'm glad to have some extra power.

Deorbit burn

I tried hard to land at the border between two biomes, to get more samples. Turned out to be tricky. Yes, I landed one km from the biome border, then took a walk there. And during that walk, away from the shielding of the spacecraft, I took a huge lot of radiation damage. I needed to cut that activity short. Eventually I managed to land 200 meters from the boundary.

Also, I managed to land with a close ice chunk. This is not the right continuity, the ship is too far. But I didn't have the right screenshot

Back to orbit. Nothing to report, except for the 66% radiation damage

5.3) A simple return. Really, I can't come up with jokes for every subchapter title. Wait, I just did.

Spoiler

The first step to finding an intercept with Economic Downturn is to get away from the death zone as fast as possible.

Just getting away from Vall

Now the ship has shed most of its mass, the remaining fuel will stretch much longer. I shouldn't have significant problems.

Removing the landing legs, for mass savings

Actually, I wanted to also remove the engine and fuel tank. I should have installed a decoupler, only 40 kg, but I didn't think of it. After some deliberation on what is realistic, I decided I'd detach the landing legs, look like they can be done fast. I'l leaving the engine, because I don't think it could be disassembled while inside a radiation belt, the geiger counter ticking. I will dismantle it once outside, when there's no hurry. As for the fuel tank, I discovered it's too big for eva construction. Should have definitely used a decoupler.

Bill reached 95% radiation damage before getting out of the death zone

Obviously my medical team has studied in depth what was the maximum dose of radiations they could give to Bill before putting him in real danger, and they worked with my orbital team to optimize the travel time from there. There's no luck involved, no trial and error. Other questions?

Some maneuvering to reach the Economic Downturn

Back to the Economic Downturn. Despite a large dose of radiations, and one month locked into a small box, Bill has kept up his spirits

At this point I had Bill just grab the samples and head back inside Economic Downturn, leaving Sole to float in space. This would turn out to be a grave mistake. I should have at least kept it on the offchance it may turn useful.

Lots and lots of science samples!

Actually, that's more samples than my reentry pod can carry. I wanted to save them all for study on Kerbin, but I will have to analyze some of them on the laboratory here on Economic Downturn.

[king of nowhere]

Part 6: The minor moons

What remains of Seated Man goes to visit Bop and Pol.

6.1) Economic Downturn to Bop

Spoiler

At first I healed Bill a bit. However, to fully heal from 95% damage it takes one year. And I don't want to spend too much time away from home. So, after a few weeks, Bill still 88% irradiated, I send him out again. No, I can't send Bob, I need someone who can fix an engine. Indeed, Bill will need to fix an engine around Bop.

This time only half fuel, deltaV costs are low

I simulated for a while, and discovered that there are no convenient times to start. My hope would have been to leave Economic Downturn on a perfect trajectory for Bop, and arrive at Bop at the right time to transfer to Pol, but such a time does not exhist. I'll have to improvise.

Trajectory to Bop

So, I start with a plane change - I picked the planar node to leave Economic Downturn. The plane change is not in the image above, but Right Answer had 2788 m/s, now it has 2411. And I make an apoapsis lowering and a periapsis raising that will send me to Bop in 36 days.

36 days later

Landing on Bop

Not much to report here. I landed on the intersection of 3 biomes, so I could fly around with the jetpack and collect 3 samples.

6.2) Bop to Pol

Spoiler

Now Bop and Pol are not in a good position for a transfer. But my life support resources are limited, and deltaV involved are small, and my ship is very light, so I'm willing to spend some extra fuel for a high energy fast transfer. It's cheaper than spending extra fuel to return to Economic Downturn and then leave again.

Trajectory to Pol

So, Bop should be a bit behind Pol for a proper transfer, but it is very far behind. I must gain ground on Pol, and this requires first exiting retrograde, going closer to Jool to go faster - I stay just outside of the death zone. Then a prograde burn at the right moment results in an intercept in 30 days. Cost is around 1000 m/s, which is over twice that of an optimal transfer, but still manageable.

At Pol

Again, nothing special here. I wanted to also get three samples, but I was running out of eva propellant, so I had to conserve it by flying high wth the jetpack on top of a hill, and then falling down the rest of the way. I'm sure a realistic mission would have walked all the way and taken a few hours, but I don't have the same patience.

Bop and Pol have value as potential refueling destinations, so I made a point of picking many terrain samples here.

6.3) Pol to Economic Downturn

Spoiler

At this point Pol is in the wrong place to reach Economic Downturn, and I only have 21 days worth of water, and 1000 m/s. When I took this approach to Pol, I was sure that would be enough to find an intercept, and indeed I was right.

Trajectory back to Economic Downturn

Indeed, it's quite a brutal, high energy approach, hitting Economic Downturn's trajectory like that, and it results in a high intercept. But I have the fuel, and I don't have any more time.

Back to Economic Downturn, with a glass of water left

I wonder if making separate missions to Bop and Pol, using more conservative trajectories, would have saved fuel or not. Anyway, the difference is small.

[king of nowhere]

Part 7: Homecoming is not easy

Economic Downturn returns to Kerbin, despite some unplanned difficulties

And it brought back almost 500 kg of samples

7.1) Preparing for departure

Spoiler

I won't need anymore Right Answer nor Seated Man. Still, I have some uses for them.

Refurbishing Right Answer

I strapped the excess solar panels I had on Right Answer, and transfered the magnetometer on it. I left it some fuel, I have enough on Economic Downturn and a few hundreds kg make little difference.  I took away its terrier engine - by now it's so light, the extra mass is no longer compensated by the higher Isp - and stored that engine on Economic Downturn, in case its own engine malfunctions. Right Answer will stay behind as an unmanned probe. A few hundred m/s is all it needs to reach orbit of the inner moons and take prolonged gravity readings of them. I even went as far as parking it in an elliptic Tylo orbit.

Here moving the engine

As for Seated Man, I was planning to just ditch it... but I cannot. I realized I didn't put a probe core on Economic Downturn. And I have no pilots on board, so no SAS. Ok, I can live with it, but it's a major nuisance. Plus, reducing stress requires to keep both my crewmembers inside the hitchhicker container, but then I have no control over the ship. Another nuisance. So I docked Seated Man, just to use its probe core. No, I could not get it by eva construction; on both sides were parts I could not remove. Anyway, it's only 600 kg.

Now, let's find a way back.

7.2) The way back won't come but once

Spoiler

The most efficient way, of course, is with a Tylo assist. Except, Tylo is always close to the radiation belt, and Economic Downturn has no shielding. I managed to use Tylo coming in, but going back it would be a lot more complicated; by now, Jool and Kerbin have moved, and the radiation belt also has moved - it always points away from the sun. So, while in theory I could reverse the trajectory I used getting in, because all trajectories can be taken both ways, in practice I cannot.

I try first with a direct maneuver for Kerbin, and I find one within my fuel budget.

Back to Kerbin in two and a half years

It would spend all my deltaV except for 30 m/s, but it's fine.

Follow two years of traveling, with some excitement - broken reaction wheels, crew getting stressed - but nothing really important. Back to Kerbin.

Detaching the reentry pod

It's a pity to see Economic Downturn burn in the atmosphere, but there's no way to recycle it

The reentry pod, on the other hand, was not supposed to burn

Hey, not fair! I specifically tested a reentry at 4 km/s. Several times.

But then, I wasn't in a perfect Hohmann transfer. My intercept speed was a bit faster. Maybe that made the difference. Back to Jool.

Similar trajectory, better intercept

This one is a modification of the previous trajectory, except it has a lower intercept speed. Maybe it will make the difference.

Or maybe go for a Tylo assist after all

I tried first the Tylo assist, it didn't work. While I put great care to avoid the death zone as much as possible, I had to take a short passage into it. And that was enough, with an unshielded ship.

This is where I regret discarding Sole. It had a shielded cabin. No, wait, it only held one person anyway. Never mind. But here I regret using an active shield instead of passive shielding. With passive shielding, this trajectory would have been possible, and would have made up for any extra mass.

So I took the other transfer.

Here I go again. This time I am 200 m/s slower, will it be enough?

Nope, I burn again.

Ok, I still have one more thing to try. Two, actually.

First, I dock the reentry pod with Seated Man. I give it the leftover fuel. I install the engine on it - I did discard its original ant engine to save 20 kg, not the best idea. I used it to slow down the reentry pod by another 100 m/s or so.

But, more important, I left it in place. The thing is, with no SAS it is difficult to keep the pod retrograde, and I noticed it does tend to slip away before burning. With a probe core, I can keep the module perfectly retrograde.

Also, maybe the extra drag will help.

And it worked perfectly!

This is a huge difference compared to the previous attempt. The crew pod didn't even start heating.

So, if I had thought to put a probe core on the reentry pod, I would have saved myself a lot of issues. Good thing I could recycle that of Seated Man.

Now at a safe speed

And that's the end. Two parachutes are overkill for that pod, one was there only as backup, so even with the added mass it splashed down in the ocean safely.

The mission did last 7 years. It's certainly hard to be away from families for so long, but it's not as devastating as a 20 years mission would have been. And you will have some celebrity status and a bunch of money at least - I have no idea how much an astronaut is paid, but for sure Bill and Bob had zero expences during the last seven years, while their salaries kept coming.

The mission only used tested-and-true technologies, with the exception of the active shield, and that's because of time warp glitches. It used the best life support simulation mod I know of, and it refrained from any of the kerbalized stunts that we usually see in the most extreme achievements.

This mission would still be judged too risky for real world standards, I think. Despite backups and precautions, there's still too much stuff that could go wrong with the crew too far away from any help. However, during the space race? At the time when a 10% risk of losing the crew was deemed acceptable? I think, back in that time, such a mission would have been approved.

Sorry, but without a kiloton mothership that's the best safety I can give.

Edited February 16, 2023 by king of nowhere