https://www.sciencedaily.com/releases/2 ... 093134.htm
How stressful will a trip to Mars be on the human body? NASA's research and testing of two twins, one who spent a year on the space station and one who stayed home, reveal a lot of facts, some of which seem to me to be confusing or contradictory - but maybe that's just me.
One thing stood out - similar physical reactions that we might not expect. A few reactions remind me of old stories of twins who were separated at birth and never knew each other still showing very similar traits, likes, dislikes, etc. In the research the twin who stayed on Earth had some physical changes that duplicated what his twin in space had.
You who understand all the technical terms herein can make more of this than I. I think we all would like to know in advance what will happen to those who take such long space journeys. Elsewhere another article talks of how the brain changes shape in space.
https://www.sciencedaily.com/releases/2 ... 142528.htm