It's mostly out of a concern about ensuring a return to normal activity after the astronauts return to Earth due to the loss in muscle mass that is guaranteed, unless said astronauts spend most of their time exercising to deal with problem which defeats the point of sending them into space in the first place.Broomstick wrote:Regrettably, NASA has been very reluctant to allow anyone other than exceptionally fit people into space even though at some point we (supposedly) will be sending ordinary folks aloft. I think it unlikely they're ready to accept disabled applicants. There are so many qualified able-bodied applicants that they have no need to do otherwise.
Long term, in terms of potential future technology, artificial gravity would take care of this problem. This would be all but required for any long term mission to something like Mars.