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Launch escape systems have been used for half a century and have worked great when tried. But entering Earth's atmosphere from orbit and landing is at least as dangerous to astronauts, and have cause about half of the tragic casualties.

What would a landing escape system look like? A way for astronauts to abort a failing EDL. Have there been any proposals for this historically? Are there any fresh ideas?

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    $\begingroup$ At launch, you have all the mass you need for your mission and all the propellant needed to get it all where you want to go. Escape is about getting the crew away from all that propellant, everything else expendable. On landing, you're pretty much down to only what you need to land safely, so there's really nothing left to get away from. Rather than adding the complexity of an escape system, it would make more engineering sense to make the landing system as fail-proof as possible, since any conceivable escape system would also have its own failure modes and probabilities. $\endgroup$
    – Anthony X
    Commented May 6, 2017 at 13:42
  • $\begingroup$ Historically, the LEM had an EDL failure procedure, and Apollo 11 came close to using it. The ascent stage would have detached from the descent stage and would have taken the craft back up to orbit. $\endgroup$
    – Jake Blocker
    Commented May 6, 2017 at 20:04
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    $\begingroup$ @JakeBlocker Worth mentioning that the Apollo LM only had an abort option because the entire descent vehicle included a separate ascent stage, which was the part that got the crew back to lunar orbit and CSM rendezvous at the end of the surface mission. At return to Earth, there isn't really an abort option - after enough speed has been scrubbed in retro fire and atmospheric entry, there's nowhere to go but down. At hypersonic speeds, there's no recovery from TPS/heat shield failure; at terminal velocities, extra redundant parachutes are probably the simplest contingency against failure. $\endgroup$
    – Anthony X
    Commented May 7, 2017 at 1:17
  • $\begingroup$ @JakeBlocker Basically what Anthony X said; an Apollo lunar descent abort was basically the same thing as a nominal take-off from the lunar surface except that the descent stage wasn't yet on the ground. (A way to abort a descent and get back into lunar orbit could probably have been designed just as well with a single-stage descent/ascent vehicle as opposed to the two-stage descent/ascent LM, but it would have been something different from what flew on Apollo.) $\endgroup$
    – user
    Commented May 7, 2017 at 14:53
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    $\begingroup$ In Vostok, the pilot could eject and land on a parachute... but that was the normal mode of landing. Landing in the capsule, without jumping out would result in at least serious injuries, as its landing speed was too high for the pilot to stay on board. $\endgroup$
    – SF.
    Commented May 8, 2017 at 0:11

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I would think it to be a sub module of the craft, to be accommodating weight and size criterion, the escape system would basically be a scalable seating module. With the actual reentry vehicle being an exoskeleton. This then being able to eject anytime during reentry. This module saving any other reentry attempts from damage caused by any sort of heat shield penetration.

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  • $\begingroup$ And if that module ejects because of heat shield penetration, what protects that module from the inferno of reentry? Even the Space Shuttle, with its large surface area facing the atmosphere, had to content with very high temperatures during reentry as it bled off speed. $\endgroup$
    – user
    Commented May 7, 2017 at 14:55
  • $\begingroup$ This module should have its own heatshield, attitude control and parachutes. Some electronics for control is also necessary and a source of electric power. A minimal life support system and a transmitter to speed up recovery. If landing on water is possible also a life raft. $\endgroup$
    – Uwe
    Commented May 7, 2017 at 20:05
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    $\begingroup$ I think the real question here is: what are the failure modes you expect from which your proposed escape system is intended to protect the crew, and whether those failure modes can be mitigated more effectively/reliably/economically by means other than an escape system. $\endgroup$
    – Anthony X
    Commented May 7, 2017 at 23:10
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Vostok spacecraft effectively had a landing escape system, the cosmonaut simply bailed out of the capsule. This is still possible, up to a certain altitude/velocity envelope.

For something at very high altitude and orbital reentry speeds, things similar to MOOSE have been considered.

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  • $\begingroup$ Can you provide a reference for the Vostok escape system? $\endgroup$
    – GreenMatt
    Commented May 8, 2017 at 15:24
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    $\begingroup$ Added a link to article providing some details on Vostok landing. The orignal thread is better sourced, though. $\endgroup$
    – kert
    Commented May 8, 2017 at 16:46

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