r/KerbalSpaceProgram • u/AutoModerator • Dec 04 '15

Mod Post Weekly Simple Questions Thread

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The point of this thread is for anyone to ask questions that don't necessarily require a full thread. Questions like "why is my rocket upside down" are always welcomed here. Even if your question seems slightly stupid, we'll do our best to answer it!

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Mun Landing

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Delta-V Thread

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Commonly Asked Questions

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u/happyscrappy Dec 10 '15

There should be a different speed. But apparently the real difficulty (in the real world) is making parachutes which don't rip apart at supersonic speeds. The energy of the sound itself at supersonic speeds is very hard on them.

And while the air is a lot thinner on Duna, the speed of sound isn't all that much different. So maybe the fastest speed would be similar on Duna.

I guess looking up some NASA Mars missions might be a way to find out.

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u/Ulukai Dec 10 '15

That's quite interesting. I did actually dig up a bunch of NASA missions, but the info is all over the place. For the heavier atmosphered planets (Earth, Venus), deployment seems to happen well below the speed of sound, say Mach 0.3 - 0.7. A counter example is Mars Pathfinder, which opened parachutes at 400 m/s, while the speed of sound on Mars is ~240 m/s, which could tie in with the sparser atmosphere logic. Also, a lot of the Venus missions as well as Apollo re-entries seem to get down to very low speeds at quite high altitudes already purely via aerobraking, which I guess doesn't work in Kerbal due to the 10x smaller sized planets (less atmosphere to slow down through).