king of nowhere

while I thank everyone who contributed with hard data, this particular paper was most informative. I regret that I only have one upvote to give you for it. so, while cryocooling wasn't the main topic, there were experiments made. the values of thermal transfer given with the use of MLI, around 1 W/m2, are consistent with a small probe only needing a few W of cooling power. With a cryocooler efficiency of 5 to 10%, which is pretty reasonable considering the theoretical carnot efficiency for the temperatures involved, a good guesstimate is several tens of watts, up to 100. that's within the capacity of probes like New Horizons or Juno, but it would place a significant strain on their power generation. For starship, the power generation needed would be in the tens or hundreds of KW - could be inconvenient, since the solar panels need to be retracted and protected during aerobraking on mars. the main issue, anyway, is indeed the way the liquid form bubbles that interfere with heat transfer. several experiments were attempted with bringing cryocoolers in space, some were successful, and it was demonstrated a prolonged storage of LOx with zero boiloff, but some failed due to heat transfer issues. sloshing is also an issue; with MMH and NTO, the problem is avoided by using internal bladders and pistons that prevent sloshing, but such solutions would not work in cryogenic conditions. it seems the system is potentially workable, and it is being investigated. However, the specific issues are caused by the zero-g environment, and fixing them requires experiments in zero g, which are very expensive to make. confronted with limited budget, it is preferred to stick to older, less efficient, but tested and reliable solutions. this is turning out to be a surprisingly common answer to a lot of things about space. many practical problems trequire to think a solution, launch it to space, test whether it works, tryto make some sense from the data coming from the instruments, think another solution, wait to launch that in space too... on earth, a team of engineers could fix it with a few weeks of trial and error. but needing to launch every single iteration in space - much less being unable to put your hands on it and having to rely on limited instrumental data to figure out what's going on - increases costs and time exorbitantly. it still does not answer my question on why cryocooling isn't employed on earth. it seems that taking air, cooling it, extracting nitrogen through fractional distillation, and transporting it to the factory to compensate for boiloff is considered cheaper than just keeping the nitrogen cool inside the tank. this baffles me. Still, a potential answer also lies in that paper, when it suggests the main issues of venting are during fuel transfers. so it is possible that the greatest losses to boiloff are not caused by heat transfer, but by fuel transfer - which, in a factory using liquid nitrogen, happens multiple times per day. it is possible the figure for 1% daily losses include those for fuel trasfer, while heat transfer losses are a lot lower. i would still like to hear about it from an expert, but it's no longer related to the field of space travel, and it doesn't belong here.

I realize there must be practical reasons if it's not done. I am inquiring about those practical reasons - because i know enough of technology to not be satisfied of just "there are problems", but i don't know enough to know what those problems are - and most hypothesis i can make on my own seem like they could easily be solved. So, your sarcasm is unnecessary and uncalled for. Similarly, a superficial answer like "in space it gets hot" does not help; sure, in space it gets hot, and it gets cold, and we already have systems in place to protect delicate instruments from that, and you are telling me we can do that but we can't handle a highly insulated tank? If that's the case, i'd at least want a more detailed explanation on the why and how. This forum is the only place i know where i can make highly technical questions and hope for people to give good answers. Many have done so; i'm going to pour over those papers as soon as i have more time. I wasn't expecting to get snide remarks and not-so-subtle insults, though. Nor did i expect such an attitude to actually get upvoted

interesting. but it leaves me even more curious as to why not include a criogenic system - as starship is big and heavy enough that the mass of one should be negligible. in general, while there are some practical problems with installing criogenic cooling units, they don't seeem nowhere near dire enough to justify accepting losses of fuel - or switching to a fuel that gives 30% less deltaV. I got the same issue with criogenic tanks on earth. i've been researching the topic because i am a teacher and i explained storage tanks to my students last month. and for all that i tried, and i found plenty of references to acceptable boiloff, i didn't find a single source even mentioning the idea of providing internal cooling. in the case of criogenic cooling on earth, clearly replenishing more material is not an issue, but i found multiple documents stating that losses of material are 0.3 to 3% of the tank content per day - which, on a large tank, means several tons per day. And I looked the cost of criogenic units, and I saw that you can buy a refrigerator that can reach -200° C for little more than 3000 $. And while I saw dozens of documents saying "losses are acceptable", I didn't see a single mention of the question "but why not avoid losses entirely?". nowhere does it say "preventing those losses by internal cooling would be too expensive" or "would entail too many practical problems". Everything I can find suggest that preventing those losses would be rather cheap - though i am unable to find solid data on that. I was just hoping someone could give me some answers on the actual tradeoff of accepting or preventing boiloff besides the ubiquitous "boiloff is acceptable".

if it's possible to insulate the tanks enough to reduce boiloff to acceptable levels - and it is, the apollo missions used crio tanks for hydrogen that would have lasted years - then you need to remove very little heat from the tanks, a power output lower than a watt. you need little to no ratiator surface for that. this also should address the power issue; it would require extremely little power to keep cool a small, well insulated tank in space.

i often hear you can't use criogenic fuels for probes because of boiloff. so you have to use hydrazine, which has much lower Isp. nobody mentions that you can make a criogenic tank that does not lose stuff over time. you just need to have your own internal cooling system that will keep the fuel cold enough to prevent boiloff. on earth it's rarely done, because most criogenics are dirt cheap anyway (nitrogen, methane) and it's cheaper to just lose some over time. at least, i think that's the reason. i saw that a criogenic refrigerator can come as cheap as a few thousand euros. in space, that cost is clearly not a problem. mass, on the other hand, could be an issue. but i don't have the numbers to make the calculations. those refrigerators i saw looked like they were small enough, could be a few tens of kilograms, though i could not find exact data (most people who buy a criogenic refrigerator doesn't really care how heavy it is). but it seems to me, adding a few tens of kilograms of dry mass should be abundantly compensated by increasing Isp by 30% or more. does anyone know the actual math of why it's not done for space probes? by the way, starship wants to use methane on mars. i suppose, to keep it cool for the nine months trip, they will use this system?

according to his profile, @JacobJHC has not logged in since 24 april. i am getting worried

putting them in less exposed parts of the spacecraft may help. use a retractable version that, when retracted, is behind some more tolerant part

in general, maneuver planning tools are not good, and nowhere near on the level of what you can accomplish with some experience. ultimately, you only need to know the transfer window to make a good transfer. just burn prograde in your earth orbit pointing to exit prograde to earth if you want to go to mars, retrograde for venus. move the node a bit, until you get the highest perihelion/lower aphelion. if that's not enough to carry you to mars/venus, increase the burn, and try again. if you don't know the transfer window, you can always eyeball it well enough.

i am not aware of any exact method in stock. maybe mechjeb has a way.

I'm not jacobJHC, but i can answer at least some yes, i've done it many times and it was accepted. the important part is, the rules say your ship must leave low kerbin orbit in one piece. so if your ship is assembled when it leaves for minmus, it's ok technically not. you may get dispensation, but it's against the rules as written. unless you really, really need it, i suggest you finish assembly in low kerbin orbit. if you need more fuel, launch an additional refuel mission from the surface to get enough fuel to reach minmus. probably no. if they are separate missions, they are separate missions. you can't use them. it's better if you don't interact with other missions not sure about this one, but i don't see why not

fuel transfer ducts are diretional. they can only transfer in one direction. if you can't transfer fuel, mount it in the opposite direction

Part 13: For science! Flying Christmas Tree 2 has collected 142744 science from Jool. It will also be my last mission in the foreseeable future. This was probably the longest Jool 5. The first save dates from early january, and that's not accounting for ship design. During the mission, I saved the game 975 times and I took 1830 screenshots. I treaded roughly 7000 km on a rover, 4000 km on a boat, I flew somewhat more than that on a plane. I grabbed every experiment from Jool 4 times. Grabbing them all once would have given 115k science; with only 3 copies, I'd have lost 600 points. Technically, one could still gather a handful more points by collecting the experiments more than 4 times, but there's no more than a few dozen points available. As I am happy to finish this mission with a new record, I am sad that it will be my last mission on ksp for a while. I've been playing 4 years, thousands of hours, and I simply did everything I did care to do. I run 3 grand tours of the stock system, once with the outer planet mod, one rss grand tour, and a whirligig world grand tour, always - except in the last case - with kerbalism to add difficulty. I did countless Jool 5, always within some additional challenge. I did a nanocrystalline diamond caveman. I did a Jool 5 within a caveman. I circumnavigated 18 planetary bodies, most of them from expanded planetary packs. I visited all anomalies except on the Mun and Kerbin. I found the green monolith on all planets. I never came even close to an Eve ssto, but from what I got explained, I decided the kind of aerodinamic solutions required for it are such that they amount to bug abuse in my book. Anyway, I can't think of anything more to do. Unless I get some crazy insight, I'm out, at least for the foreseeable future. I'll keep lurking the forums. I may try ksp2, it may have some new challenge to attract me. I will carry this game inside me, always.

Part 12: 100% completion I recover the crew on Laythe; realizing I visited everything except the monolith on Tylo, I also go there. 12.1) Bring them back 12.2) The last anomaly

Vall too. This will be my last one for a while, if not ever. I considered getting the master circumnavigator, but I'm not driven enough to circumnavigate the missing planets. Actually, I started a Mun circumnavigation months ago, but I gave up one quarter of the way. Same for a Tekto circumnavigation. The thing is, I've been playing this game 4 years, I've done all I really wanted to do, I haven't found any new interesting challenge to try after

If I send back a single copy, I get 125,1k science. your calculation, I assume, is made by calculating the science values in the wiki. but those science values are the maximum amount of science that can be collected, over multiple samples. if you take a single samples, most experiments do not return 100% science value. hence why you need to carry back multiple samples. your calculation, most likely, gives the maximum theoretical value, minus the "recovery of a vehicle from" extra bonus (in this case i get 120 for "returned from tylo surface") i also checked removing a single set of samples (so 3 copies of each experiment, but 4 for the infrared telescope) and I got 142145, 599 points less than I got. a fifth set of experiments would have returned a few additional dozen points. i'm sure i could calculate an ashyntotical maximum for the curve if i put myself to the task.

Part 11: Memory lane is not over yet Leaping Mantis ends the circumnavigation of Vall, passing - sometimes by design, sometimes by chance - more landmarks encountered in previous Vall missions. 11.1) Return to the Great Wall range 11.2) The name of a mountain 11.3) Return to Rover Crasher peak Science recap

I finished my current run. I set to improve my previous record, I ended up pulverizing it. I had no idea there was so much science I missed before. Now I really think I got all of it. There may be a few dozen science points left from the multiple grabbing of the same experiment; I got 4 copies for each, which is enough for over 99.5% recovery, but grabbing a fifth copy should still earn a few fractions of point. But no more than that. I still have to update the report thread, I plan on doing it tomorrow, the day after at the latest. But @JacobJHC generally takes some time to review, I may as well post now.

I completed the new Jool 5 science record. I got all experiments from all biomes, in quadruple copy because some experiments will give extra science if collected more than once. quintuple copy for infrared spectroscopy, because it's the one where multiple copies are worth more. And because I had a convenient place to store them, while only carrying 4 containers in all my landers. For Laythe, I took both landed and splashed down science (it's 2 different sets of science reports) for 8 biomes. I landed the exploration plane on an aircraft carrier to trick the game into giving the landed condition for all water biomes. Only now I think a submarine could have achieved the same, and it would have been a lot easier to fly than an aircraft carrier. that thing was a huge aerodinamic problem to launch and a huge center of mass problem from the moment I docked it to the mothership to the moment I dropped it on Laythe. I circumnavigated all moons. I visited all anomalies. I forgot a reentry vehicle. Fortunately, the only lander I did not discard, the plane I used for Laythe, is capable of ssto on kerbin; so I can land it, drop the pilot, send the plane back to orbit, dock with the mothership, refuel, get another crewmember, carry it to the ground, go orbit again... repeat for 9 crewmembers. so, technically it's not finished. I could also just launch a capsule, the rules allow it, but it's less nice. I also have to finish writing the report. A few more days. However, this is a momentous moment for me. After four years and many thousands of hours, I find myself without any ongoing project for this game. I've done everything. At least, everything I was interested in doing. 3 grand tours of the stock system with kerbalism; once including the outer planets mod. A grand tour of the real solar system, one of the whirligig world mod. More jool 5 than I can recall, always with some additional condition. A nanodiamond caveman. at least 18 planets circumnavigated with a rover, many of those planets from mods. I visited all anomalies (ok, i didn't bother with all of them on the mun and kerbin). found 21 green monoliths. Now, whenever I think of something about this game, I've either done it already, or i'm not interested. I'll probably stop playing ksp, after all this time. Maybe i'll get ksp2 eventually. As a science nerd, this game struck me in all the right places. Only the civilization saga has left a similar mark on me. Likely, even 10 years from now, even if I never pick it up again, I will still name ksp as one of my favourite games. Or maybe I will I find some other long term challenge to waste my time tackle after all.

I have seen a fully reusable grand tour that managed a purely rocket ascent from eve. it did so by landing on a 6.5 km tall mountain on the equator. from there, it was possible to orbit. so, 12 km will also give some payload capacity.

circumnavigation of Bop in the same thread i also circumnavigated laythe, but I already had a previous elcano there, it's redundant to post another one

why not? i ran a full grand tour of it, radiations were no more of a problem than in previous runs. less of a problem, actually, because i had more experience dealing with them. the only real bother way, i could not land a crew in the inner moons of saturn because of too many radiations. but few people use kerbalism to send a crew on saturn anyway. you may refer to the fact that travel times are longer while radiation exposure is the same, but if properly handled, radiation can be virtually nullified for most situation. so if the mission is longer it doesn't really matter

i played with rss and kerbalism without changing anything. of course, going to orbit is going to be exceedingly difficult with stock parts, but that's not a kerbalism problem

first of all, the thread title does not match the question. orbits refers to moving in space, ascent would be more appropriate for atmosphere. it seems your rocket has stability problems. unfortunately, you do not give us enough information. pictures would be good. maybe your rocket isn't as aerodinamically stable as you think. or maybe you are turning it too hard. why would it be a problem especially for going to mun? how is that rocket different from others? this may shed light on the problem

Oh, right. I forgot to mention in the Elcano thread I did Bop, in chapter 9. I also did Laythe, but I already had a circumnavigation there, I don't see the point of making another claim. I'll be busy at work for the next couple of weeks, so i expect Vall to take more. Shall I post the Bop notification in the Elcano thread for the sake of linking?

Part 10: A trip through memory lane Leaping Mantis goes to Vall. This first part covers from the equator to the south pole to Vallhenge. Some of that road I already covered four years ago in one of my first challenges. I got a bit nostalgic about it, hence the chapter title. Standing above the southern pole terrain glitch 10.1) Need for Speed: Vall 10.2) Return to Kraken Maw Peak 10.3) Return to Shadar Logoth Trail and Vallhenge