We’ve known for a long time that long durations in microgravity does the human body no favors. Scott Kelly’s year in space has helped nail down the effects, but a lot of confusion remains.
What a Year in Space Did to Scott Kelly
A lot of it boils down to “things changed while in orbit and changed back when he came back to earth. Some effects went really weird… his cognitive function went *up* in space, dropped well below normal when he came back, and slowly crawled back up… but not to the pre-flight standard.
So far as we know, there are three main influencers on human physioloy while in space:
- Stress
- Lack of gravity
- increased radiation
The lack of gravity, of course, can be dealt with… just build your space stations and long duration spacecraft with artificial gravity in mind. Stress… shrug. Being in a tin can in space is probably gonna be stressful no matter what you do. Radiation… a few tricks can be played, but until the time we’re building spaceships so vast that several *meters* of physical shielding separate you from the cosmic rays zipping around, radiation is just going to be one of those things.