[frederikvs]

John McFall, the person chosen for the parastronaut study, probably is one of the very fittest humans we can send. Participated in paralympics and all that. He probably runs faster than many of the other astronauts that made the selection.

Additionally, when in weightlessness, a missing leg is not that much of a hindrance.

[modo_mario]

Cool. But what's the point of this study? What are we learning from it that one couldn't tell you already?

[frederikvs]

I'm not involved with the study, just a bit of space nerd, so this is just an outsider making a guess. But I see 2 aspects to it.

The first is a whole bunch of practical questions. Do they need to modify the spacesuit to account for the prosthetic? Is it better to create a new prosthetic to fit the suit and/or the station? Does the missing leg cause issues with the exercise equipment on station? What other practical limitations are there?

Secondly, it's simply a way of seeing how it goes. We don't expect any big obstacles, but you can never know for sure until you've tried it. Once it's been done, and we know the obstacles, it can become just a normal thing to do.