The European Space Agency writes to say

◾The applicant must have the normal range of motion and functionality in all joints.

Historically, IMHO, astronauts came from a flight/test-pilot background. Physical fitness may have been mandatory for orbital flight, and for the lunar programme. It may even be necessary for any missions that involve actually landing on a body exhibiting significant gravitational attraction.

NASA and other Space Agencies have similar physical mobility requirements from their astronauts.

Wikipedia writes to say

What began as the selection of military fighter and test pilots in the 1960s, with a considerable focus on physical capability, has evolved into a selection that now selects for aptitude in engineering, sciences, life sciences, and mathematics

Say instead the astronaut is headed to the ISS where she/he is expected to be in free-fall most of the time. A person with a reduced range of motion (I'm specifically of the mind of restricted movement of the lower-limb) might actually be better suited for free-fall - as long as other physical, social, mental health parameters are met. About the only time I imagine full-range of motion in the lower-limb/s might be necessary would be at launch/landing.

I've never been an astronaut, or even close to medicine let alone space-medicine so I may be wrong. Feel free to poke me in the rib if my premise is flawed!

  • Do astronauts aboard the International Space Station (ISS) actually use their legs? (Goes without saying they're in Earth orbit since they are aboard the ISS)
  • Is the physical fitness requirement that an astronaut prove full-range of mobility in all limbs relevant to astronauts headed to the ISS, or low-gravity bodies such as Phobos/asteroids?
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    $\begingroup$ Interesting question. I wonder if a double-leg amputee might actually be more mobile in microgravity than a person with legs. $\endgroup$ – Philipp Oct 14 '13 at 8:43
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    $\begingroup$ @Philipp: My motivation precisely (+: $\endgroup$ – Everyone Oct 14 '13 at 8:55
  • $\begingroup$ @Thomas Why not? I would of course never suggest to ampute healthy legs of an astronaut, but why not send an already disabled mission-specialist up there (provided they are qualified and fulfill all other physical requirements)? It could make sense both for scientific reasons and as a great example for integration of disabled people. $\endgroup$ – Philipp Oct 14 '13 at 14:05
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    $\begingroup$ Couple things to keep in mind when riding this train of thought; first, emergency procedures, such as a hasty exit from the craft while in the atmosphere, typically require the ability to run and jump, neither of which is at the top of the abilities list for a double amputee. Second, while the lack of legs might be an advantage in micro-gravity if planned for, everyone who's ever been to space has had all four limbs, and so all the equipment, from space suits to sleeping bags to exercise equipment, is designed accordingly. $\endgroup$ – KeithS Oct 14 '13 at 21:56
  • $\begingroup$ @KeithS: The first part of your comment was the reason for the question on cross-training space.stackexchange.com/questions/2405/…. With reasonably clear separation of mission specialists from flight crew, it becomes possible to plan for mission specialists with limited motion in the lower limbs. The other concerns you mention about procedures & equipment are relevant; I'd like to focus this question on mobility though (+: It would be great if you could build your comment into an answer $\endgroup$ – Everyone Oct 15 '13 at 4:35

Yes, astronauts do use their legs.

In weightlessness, any movement you make (even tiny things like pressing a button) will push you in the opposite direction. At many workstations, footholds are provided. The astronauts use the footholds to hold themselves in place, so they can use both hands for the work they're doing instead of continually needing one hand for stationkeeping.

Photos of footholds being used
Another photo
Chris Hadfield demonstrating use of footholds in his music video

When the robotic arms are used during a spacewalk, the astronaut is generally attached to the arm by his boots. lots of photos

  • $\begingroup$ TY That helps; albeit foot-holds may be convenient, and moot. Can you expand the answer a little more please? To try to cover the other question, if possible? $\endgroup$ – Everyone Oct 17 '13 at 19:06

I would love to see/hear about amputees in space, first off. Gives hope to all of us who are not the NORM...

However, you would still need the ability to move around the ship without bouncing into controls and knocking into others aboard. In my mind that means the ability to use your legs full range of motion to kick off or slow your momentum down in addition to the use of hands/arms.

What if you need to move a sensitive electronic from one side of ISS to the other? I'm sure there are all sorts of things that could come up where having a fully agile individual is needed to deal with the problem. Saying that however, if we put a few NASA heads together we could come up with solutions to most anything that would arise... and I do imagine that in the future amputees will be as useful and indispensable as any other crew memeber.

  • $\begingroup$ (+: Welcome to the site! I might be wrong, but at-least part of your concern may be mitigated by due caution; IMHO the adage 'Look before you leap' is nowhere more true than in free-fall. Hopefully a team of experienced personnel could come up with a set of recommendations for most concerns though ... $\endgroup$ – Everyone Oct 16 '13 at 3:06
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    $\begingroup$ +1 and it might be interesting to point out that the Robonaut 2 still doesn't have its own functioning legs and is useful onboard the ISS nonetheless. It might get legs come the end of this year, tho. Legs, while of course useful as two additional limbs one can push with against any other surface, are not that essential in microgravity and I'm as well surprised there wasn't any astronaut with impaired leg function yet onboard it. It is not that hard for a physically fit amputee to push against surfaces with the torso, or against fixed prosthetics. $\endgroup$ – TildalWave Oct 16 '13 at 10:24

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