king of nowhere Posted June 23, 2021 Share Posted June 23, 2021 (edited) Part 0: introduction and fluff Starting my next mission. Once more, a giant mothership and a bunch of service shuttles. This time, the outer planet mod is included. The mission will involve ISRU with the full kerbalism rules. Ever since discovering the complexity of kerbalism isru, i've been wanting to try it. The problem is that it requires so much energy, I'd need a nuclear plant. Good thing the near future technologies provided one. Also, since discovering the outer planet mod, I've been wanting to include them in the next grand tour. Well, why not both?0.1) Speech from Walt Kerman, announcing the next great mission Spoiler Quote As you know, the "Dream Big" program aims at creating a generation ship to send kerbal settler across the vast interstellar distances, to settle new star systems1. The program is based on incremental missions, especially since we don't have the technology to cross interstellar distances anyway; we'll send more and more elaborate spaceships in more complex missions, testing at every step what we can do with out current technologies and where we need to improve. The first mission tested long-term endurance on both the crew and the spaceship. Crop growth in space. Radiation resistance.In-situ-resource utilization, though that used some help from our Duna outpost2. From it, it was clear we'd need better ways for our kerbonauts to cope with stress and radiations. It was also clear we'd need alternative energy sources; we knew from the beginning that we could not cross the emptyness between stars on solar power. The second mission tested alternative radiation shielding (which was unsuccessful), radiation remediation (which was instead a huge success), recycling of resources, and planetary exploration. As we felt more comfortable dealing with radiations, we also tested the first applications of nuclear energy and nuclear rockets. We powered Bolt with RTGs. But RTGs also are not a viable solution to cross interstellar distances. They run out in a few decades, and can't be recharged without a nuclear reactor on board. Bolt also highlighted the limitations of trying a mission without gathering resources from the environment. For our final goal, it's just not practical. But if we wanted to move past depending from a land base, we needed more power, because extracting resources requires a lot of energy. So, again, we needed a nuclear reactor on board. But while our kerbonauts toiled in space, our scientists and engineers were tackling the technical problems. And so now, ladies and gentlement, we are ready to unveil the third mission for the "Dream Big" program. With a nuclear reactor on board! view from above, in space, with shuttles docked view from below, mothership alone view from above, mothership alone A Mun landing is a bit of a spoiler at this point, but I didn't have any other good shot of the ship from the side This time we will, again, visit all the planets in our solar system. Including the outer planets of Sarnus, Urlum, Neidon, and Plock, that we skipped the previous time3. And we will do it while gathering resources from the planets themselves. Without any support base. This new ship has everything it needs to survive the test of time using planetary resources; not only it can gather fuel, water and nutrients, it also has 3D printers to fabricate spare parts with the local materials4. This ship has all it takes to reach an exoplanet and start a new outpost. Except the capacity to actually get there; our scientists are working on that too. Questions? Quote Sir, when they saw the expence bill from the DREAM BIG, many taxpayers had a heart attack. You promised Bolt would be cheaper, but the cost for that one skyrocketed too. And now this new ship is even more expensive. Some people are wondering if we should just pull the plug on this program. That guy is very funny. Show him to the experimental prototype testing range; I'll start drafting a condolences letter to his family as soon as I'm done with this press conference. 1) While I choose my missions for the challenge - because I like making megaships and having huge missions give me a chance to project some that have an actual purpose besides looking good -, inb my head they are linked by a common story. The kerbals want to go interstellar. They want to make a big generation ship and send settlers on new star systems. Of course they don't have the technology, they don't even come close, but they are taking this incrementally. First they make a huge ship, and they send it on a long trip. Then they analyze the outcome, see what worked and what didn't, make a better ship, and send it on a longer mission. Eventually, they'll get something that can last for the millennia needed to cross interplanetary distances. It also explains why they are making grand tours instead of smaller missions to individual planets; the real goal is to test bigger ships for longer durations. Getting planetary science is just a bonus. 2) that was my mental canon for allowing myself to use stock isru in the first mission: there was a Duna outpost helping along. Because I calculated that I could have actually have done it, but it would have been too much of a bother. 3) This is my mental canon for the new planets: they were always there, they were just skipped before because the kerbals didn't feel ready for them. What? Did you just think they popped up from nowhere, just like that? That would be completely irrealistic 4) and this is my mental canon for why my engineers can keep "servicing" the various hardware to keep it in working conditions (which will inevitably include the need for spare pieces) without ever running out. 0.2) Kerbalism, ISRU, nuclear plants, and me Spoiler In kerbalism, fuel is methane, and oxydizer is hydrogen peroxide (which is not realistic, as a chemist I already remarked on this. But I don't expect them to change the whole mod for it, nor would I want them to). The second can be obtained from hydrogen and oxygen, both available from water. The first requires a source of carbon too, plus hydrogen, that again comes from water. Water is not very common. In fact, water is far less common under kerbalism that it should be in reality (actually, kerbalism uses the rational resources mod for resource distribution; I already commented on it on the relevant thread). Water is the single most abundant compound in the universe, and while it is rare in the inner rocky planets - evaporation and solar wind tend to strip it away from all the planets without a strong magnetic field, that's what happened on Mars and Venus - the outer planets are made mostly of it. While in my case I can't count on that. Anyway, water is found on most planets. It requires large amount of energy to break it into oxygen and hydrogen (I actually made a calculation, based on the energy production of a gigantor panel and the actual energy output of a solar panel of similar size, and it turns out, the value is fairly realistic), but nothing that can't be managed. The main problem is carbon dioxide, the sole carbon source in this mod. It is found in Duna's atmosphere. But aside from that, it must be mined from "ore". Now, according to those who made kerbalism, "ore" is regolith, and regolith is very poor in carbon content. You have a chemical process to extract CO2 from ore, but it's slow and energy intensive. And by "slow and energy intensive", I'm saying that a large convert-o-tron will require 200 electricity/second to produce 0.4 units of carbon dioxide. You then need 7000 units of CO2 to make 1 single unit of liquid fuel. 17500 second, practically one kerbin day. For 5 kilograms of fuel. With a 4.5 tons piece of machinery. And several large drills to provide enough ore. Assuming you can feed it 200 electricity per second. Looks like a lost cause. But it's technically not impossible. So of course I was looking for ways to do it. And hey, there are ways. One is to refuel at Duna. You get CO2 from the atmosphere practically for free. Only problem, you still need to perform water electrolysis, you need energy, and Duna is a bit far from the sun - and it has a dusty atmosphere reducing solar panel output. Still, I planned a mission with this premise. It would use two ships, one on Duna doing nothing but gathering fuel, slowly, over several years, and bringing it to an orbital depot. The second one would then reach Duna, dock with this depot, get fuel, and move on. I didn't do this because I had no enthusiasm in it. The exploration ship would basically be an improved version of the DREAM BIG. It would be little more than a rehearsal of a previous mission. Not interesting enough. I also planned a ship that could refuel by getting CO2 from ore. It needed lots of solar power, so the only places it could actually work are Mun, Minmus and Gilly (the other inner planets have no water whatsoever). If my calculations are correct, it would have taken 90 years to refuel. The problem is, once you are on Duna, it takes little fuel - and some gravity assists - to reach Mun or Gilly. By refueling there, I don't really gain much. So, I discarded that plan too. By this time, I also started to think of the outer planet mod. And I actually tested a solar powered ship on Plock. 120 gigantors. 1 electric charge generated. It would not work. With the DREAM BIG I could brute force the power generation issue with moar solar panels, but it was no longer possible. At the same time, I didn't want to use RTGs for this mission - as I said in 0.1, they would gradually lose energy, and in my fluff the kerbals are actually trying to make a ship lasting millennia, so they know RTGs would not work, and they would not use them. Yes, for all that I play for the challenge, maintaining some fluff is important to me. It's also why I go out of my way to perform science everywhere. So, I went looking for nuclear plants. And there were some compatible with kerbalism. That would solve all my energy issues. In other circumstances, this would have felt like cheating, except that those super powerful reactors also came with inconveniences: - they actually use nuclear fuel. Which won't last forever, and I have to mine new one on planets. - they are very heavy, especially high quality. - they have a high rate of accidents. They are not some magical gift from the sky solving all my problems; they generate their own set of problems, that I must plan around. And so I feel I can use them. 0.3) First ship concept Spoiler So, I solved the energy problem, but there was still the time problem. Even with energy aplenty, ISRU would still require many years, and a lot of heavy machinery. First, I needed a ship that could last for a lot of time. But I made certain, in my previous missions, that it is possible to last long with proper maintenance. Still, this mission will be much longer, so I decided to put some order in my redundancies. I settled on 6: every critical system will have at least 6 copies. Or 12, if one copy is not enough for the ship to function. I also took full advantage of EVA construction by including spare parts. Second, I needed a ship that could actually land. The machinery needed for ISRU is so heavy, there's really no point sending down a lander. That "lander" would be bigger than the rest of the mothership. May as well land it all, so I have all the conveniences of my full mothership available. So the ship will need a decent thrust, requiring chemical rockets. But the heavy machinery also forces a high dry mass, with the additional hurdle of having to spend fuel to take off and conserve it to land for the next refueling. This requires nuclear rockets to actually go anywhere. Third, I need to protect the crew from radiation. While the ship is landed on the ground, it's basically sitting duck for any incoming solar storm. A simple shield won't suffice anymore; it needs to be covered from every angle. So I had the idea to build a ring of fuel tanks on the outside, and place the crew space inside. I actually experimented with carrying, again, hundreds of radiation shields. But the combined weight of shield + convert-o-trons was too much. At this point I needed a name. This ship has a hard exterior, a shell to protect its soft interior. Sort of like a turtle. It is also round, like a turtle. It has six appendages jutting out, which could fit with the turtle theme: the four limbs, plus head and tail. A giant turtle gently floating through cosmos, carrying life. It felt very fitting. And so I hope I'm not being presumptuous in calling this new mothership A'Tuin. May it have a fraction of the cool adventures of the creature it homages Edited August 16, 2021 by king of nowhere Quote Link to comment Share on other sites More sharing options...
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