king of nowhere

i can't recommend you an engine because it depends on the craft. but I can recommend three things: 1) don't rocket brake before duna's atmosphere. you said you brake to 1000 m/s, you arrived presumably at 2000 m/s, so you spent 1000 m/s. you can save that. worst case scenario, you can brake less and still save at least 500 m/s. that alone is enough if you're tight. 2) you mention having problems with low thrust, needing a long burn to stop. this is bad. you probably have an engine too small. a bigger engine would help. yes, a bigger engine is heavier and makes you lose deltaV, but it's a lander, you have gravity drag for low thrust, you waste more deltaV by that than you lose with a bigger engine. 3) include parachutes in your lander. without parachutes, you'll fall at over 100 m/s, maybe up to 300 m/s, depending on the shape and size of your lander. with parachutes, you'll fall between 30 and 50 m/s. you save a lot more deltaV than you lose by their mass. and you can remove them before leaving, either by eva construction, or by putting them on decouplers

oh, i see. then the problem is not the aerobraking process, but the landing itself. yes, duna's atmosphere is thin, so it won't brake you much. parachutes would help, but you still need rockets. it doesn't matter the periapsis you set. rocket braking down to 1000 m/s before entering atmosphere was exaggerated. you could have managed with a higher speed for sure. well, it seems you managed anyway

wait, wait, wait, those speeds make no sense. escape speed from duna is somewhere between 1400 and 1500 m/s, I don't remember. so, if you come from outside, that's the speed you'll pick up falling towards duna. that's the minimum possible speed you can have. To that you have to add your intercept speed (well, a bit less, for the way energy works), so a normal speed to enter duna atmosphere is 2000 m/s. I therefore have no idea what those 750/1000 m/s you mention are. and 2000 m/s is an easily survivable speed. it's slower than you enter kerbin's atmosphere, and one routinely does that with unshielded crafts. So I see a feww options for what went wrong 1) you were not in an optimized trajectory to duna. You took a bad transfer, leading to much higher intercept speed (even a few hundred m/s can make the difference), leading to faster aerobraking, leading to death 2) your rover is fragile. maybe it has heat sensitive parts, like a science jr, in exposed positions. check maximum temperature of parts in the VAB. most parts have 2000°, that's the "standard", and that's what survives a 2000 m/s reentry. parts with lower heat tolerance are bad for aerobraking. 3) you just were too low. I didn't think it's possible to actually break a lander by aerobraking from 2 km/s, but maybe I'm wrong. Anyway, 10 km is very, very low. you get in the low atmosphere very fast. i suppose it could be a combinaton of all those factors

there is a specific tutorial for that, just play it

the editor may have a glitch. I suggest you perform the manual calculation yourself looking at the habitat volume of given parts divided by crew members. it's not a big calculation, fortunately

alas, that I have no idea. wait, is habitat size wrong? maybe you are mistaking habitat per person against total habitat? in that case, if you have many kerbals on board, that could be the case. i seem to remember float required a lot of space per kerbal. if it's not that, then i have no idea

i'm not familiar with the current version, but in the previous version you could not. maybe you can edit the file? I'm not sure EDIT: I went to check one of my old mission reports, because I remember having an issue with enabling/disabling habitats. Yes, you can enable/disable by editing the save file. there should be the option "habitat" that you can manually change

aerobraking is a matter of speed. if you go too fast, too shallow, you burn. but if you don't go shallow, you don't brake. hencefore, what makes duna uniquely suited for aerobraking is not its thin air - which is actually no different from other upper atmospheres. duna is unique because it is small. you arrive at a planet with your intercept speed. for a kerbin-duna transfer, it's generally 400 to 600 m/s. then you fall towards the planet, so you have to add the escape velocity from the planet to your intercept speed. on kerbin, this would result in speeds well over 3000 m/s, which incinerate most parts. eve is even worse, and laythe is only slightly better. but duna has a very low escape speed. you can reach it from interplanetary, and still be no faster than 2 km/s, which is totally survivable. still, heat sensitive parts - like some solar panels - won't survive that. so make sure there aren't any; use retractable solar panels, those are very strong, or put your solar panels in shielded positions. as for height, you can only figure it by trial and error. my experence is different from @Vanamonde, I generally get by with periapsis between 20 and 25 km. perhaps the difference is because i want to brake, but to stay in duna's orbit, while he wants to land directly. regardless, save the game before the encounter and try different periapsis until you find the right one.

it's also possible, depending on the difficulty setting, that the rocket is losing communication. really, we need more information

yeah, but that wasn't my question. This is of little practicall relevance, because you very rarely want to use a gravity assist to pull a 180° flip. My question arose because I came to a gas giant with 500 m/s intercept speed and I used a large moon for gravity capture and it worked fine, and then I came at another similar gas giant, with a similar intercept speed, and I tried to use a similar moon for a similar gravity capture, and this time I could only get a minor saving. @Leganeskianswer about intercept speed is probably it

I interrupted my regular routine for an important new. Today died Piero Angela. I don't think he was famous outside of Italy, but in Italy there's virtualy nobody that doesn't know him. He wasn't an italian science communicator, he was THE italian science communicator. His name was practically synonimous with documentariesto the point of entering common language. Perhaps his closer equivalent was Neil Degrasse Tyson, but I don't know if he's equally popular and pervasive, and for seven decades. Piero Angela raised generations of future scientists. So I prepared a little tribute to him This is Pieroangelsat 1. It's got a huge communication array that it uses to stream science documentaries nonstop.

the thing about alignment of the velocity vector is a good point. my periapsis was at Io's level, and I could get less help from Io than I could from Ganymede. I guess I never realized this because I had many Jool missions when I took gravity assists from Tylo at periapsis; but tylo is a lot bigger than any of the real life moons, so perhaps it's strong enough that even an inefficient assist is enough for gravity capture. as for the intercept speed, I'm not sure it actually affects gravity assist. I used Mun for a lot of manuevers, some of them even at very high speeds. There was one instance where I zipped past Kerbin at 4 km/s intercept speed, and I used a Mun flyby to refine the gravity assist, and I could squeeze some deltaV from it even though it was five times faster than the normal speed of a Mun intercept. On the other hand, it certainly makes intuitive sense that spending less time close to the body will result in less change in trajectory. Do you know this for sure, or is it a speculation? Spheres of influence may be relevant here too - though of course they don't exhist in real life, they affect how this game calculates trajectories. Ganymede is close to Jupiter, and its sphere of influence is rather small.

well, i didn't check. I am running an elcano challenge on wal, and i stumbled over that mountain accidentally. i actually thought wal had mountains above 30 km (was confusing with priax) so I thought nothing of it. until i run halfway around wal, found very few mountains above 20 km, and went to check this thread to see where the 30 km peaks were. I can't really replicate the process for another planet

i found a sizable mistake in the chart. wal has at least one point that is 100 meters higher than the record given in the table (indicated as 20660 m and 3 degrees eastward)

a gravity assist does not change your velocity relative to the planet. it changes your velocity relative to the sun.

yes, if you could pass through rock, then you could get the same assist regardless of the mass of the body. but you yourself recognize that the practical limit is skimming the surface (or the atmosphere), and that defines how much you can get from a gravity assist. as for 2x of the relative speed, that's not helpful. that's just a specific case of the more general principle "you leave with the same speed at which you arrive". relative speeds in rss are generally of many km/s anyway. by "how much deltaV you can get from a gravity assist", I obviously mean by passing as close to the surface as safely possible. In stock, I was used to know how much I can get from a specific body. From Mun, I could get 100 m/s. To get to duna you need 1000 m/s, with a mun assist I could do it with 900 (yes, I know multiple assists make it cheaper, i never bothered for such a small gain). To get to jool i'd need 2000 m/s, with a mun assist I could still save 100. tylo gave... maybe 500? not sure, but it was consistent. Now in rss it doesn't seem consistent anymore, bodies of similar size giving wildly different results in different situations. P.S. It just came to my mind that it may be possble to just aim for a lithobraking trajectory and use high time warp to glitch through the planet, getting a bigger boost from the gravity assist than otherwise possible. but here i'm talking of real physics; and for gaming purpose, I'm against exploiting bugs anyway.

update: now i'm using ganymede for a plane change, it would cost 900 m/s with rockets but ganymede is giving it for free in one pass. so how is it that I can get 900 m/s of gravity assist for changing plane, but I couldn't get more than 200 m/s for gravity capture?

sometimes the game is bugged. i once had a perfectly sound laythe lander that failed because it was made by two docked parts, and the game was modeling it as if both docking ports - that were docked with each other and perfectly in line with the stack - were fully exposed to the air flow,, thus tripling the drag my poor rocket was experiencing. But you could use the bug to your advantage! if those decorations are causing drag, you could try to move them on top of the rocket, so that they act as airbrakes. you could even skip the actual airbrakes at that point.

it could be that they are generating additional drag. you can activate drag visualization in different ways, from the alt-f12 menu-physics-aerodynamics. check if those parts are making drag. or just try to remove them and see what happens. worth a try

in moving from stock to rss, I noticed some weirdness in the effectiveness of gravity assists that brought me here to ask just that. i mean, of course the bigger (more massive) the body, the more of a slingshot you can get, but there are some additional factors I'm missing. in stock, I started from duna to kerbin, wanting to move to a kerbin-eve hohmann orbit. for that, kerbin's gravity wasn't enough; I had to eject into a resonant orbit and take two gravity assists to complete the manuever. i moved to rss, in a totally similar scenario: starting from mars, going to earth to take a gravity assist ad get into a earth-venus hohmann orbit. this time, a single earth flyby was enough to do the trick, and I didn't even need to get very close. so I figured yay! gravity assists are a lot more effective in rss. perhaps because everything is bigger and so you spend more time under the gravitational influence of the planet. then I tried to take gravity assists from the moons of jupiter. it was an abject failure. oh, i can get assists, yes, but they are very small. I'm currently using ganymede, the biggest one, to reduce my injecton deltaV, and even though i'm making a close pass at 15 km from the surface to maximize the assist, I still am saving only 150 m/s. maybe 200. that's barely more than what you get from Mun in stock; and since everything in rss costs triple, it makes those assists a lot less effective than Mun gravity assists. attempts to use the moon for gravity assists - also frustrated by its highly inclined orbit - were equally fruitless. on the other hand, Titan - which is also close in size to the moon - was quite effective, maybe 500 m/s of deltaV change in a single passage. So I have this paradox; in going from stock to rss, gravity assists from planets appear to be a lot more effective. But gravity assists from moons appear to be a lot less effective. there also appear to be a huge variability between moons of similar sizes. can anyone explain me why?

When you are in a hyperbolic trajectory, you only pass near the planet enough, and you must aerobrake all your intercept speed to get captured. else you have no capture. for this you need a more resistent ship, else you have to perform the manuever with rockets. when you are in an elliptic orbit, you can always aerobrake. if your ship burns, just use a higher periapsis. you will brake less, but it's not a problem because you are in orbit and you will pass in the atmosphere as many times as you need. so you can circularize without any kind of thermal protection. in theory. in practice, not so much. when you are in a high elliptic kerbin orbit, you reach periapsis at 3200 m/s. At that speed, you can aerobrake 20 to 50 m/s with an unprotected ship. as you slow down, you can take shallower passages and brake more. It may take a few dozen passages, but you can circularize your orbit in a few hours of gaming. when you are in high elliptic eve orbit, you reach periapsis at 4.7 km/s. at that speed, you burn almost instantly. you can brake maybe 1 m/s with an unprotected ship, if you're lucky. and that's not a significant braking, so you can't brake more on the next passage. so you would need a thousand aerobraking passages to circularize orbit, whch are not really feasible. that's what I mean when I talk of time.

no. the only place in the stock system where you can safely aerobrake from interplanetary without shields (or without a specialized spaceplane, of course) is duna, due to being small. on kerbin, though, you can circularize without shields in a reasonable amount of time.

it only uses stock parts. parts in the stock expansions breacking ground and making history, sure. but not modded. basically, the game has a list of parts that it can ask to test, and it only asks those

You have a simple way to determine it. When you plan the manuever, where you make the close passage into eve's atmosphere? placea manuever node there, and simulate a capture burn. the simulation says you need 400 m/s before you get in orbit? then aerobraking saved you 400 m/s. which is more or less what you actually save for capture at eve, coming from kerbin. do notice that once you are in orbit, you can circularize by short passages in the high atmosphere, even without shields. well, ok, not really at eve, not unless you are happy with losing 0.5 m/s at every passage. but the point is, once you're in orbit you can circularize with time, and it takes little protection. so the heavy shielding only saves the capture deltaV. Not that you want to circularize a mothership anyway, you only circularize the lander I generally don't bother aerobraking at eve, because intercept speed is relatively low and you need a lot of thermal shielding; easier to burn some fuel. On duna i aerobrake hard, instead, without needing shields.

Part 8.X SPINOFF: Nothing is impossible with enough mass to orbit One can get infinite deltaV with an infinitely big rocket, provided one has infinite patience The unmanned landings on Saturn left me missing something. I calculated that it would be possible to move safely in the inner Saturn system with 10000 tons of radiation shields. I decided to make a spinoff challenge to do just that: safe manned landings on the inner moons. or this purpose I designed and assembled Ringrazer, a 200k tons ship - 30 times bigger than A'Twin. The outlook looked good. However, after one month of building up massive stuff, realizing it was going to take a lot more time, I grew tired with the effort. But it would have been possible. This spinoff is not part of the grand tour mission. Ringrazer in all its illogic glory. It doesn't give much of a sense of scale, until you look at the tiny bit on the left and realize those are Mk3 parts Spinoff.1) What would it take? Spinoff.2) Massive launchers galore Spinoff.3) You must wear a old man's hat to drive this And now, back to the real mission.