Detailed text transcripts for TV channel - MSNBC - 20150814:21:56:00
Period of time presents a lot of challenges. >> that simulation makes sense and also makes sense to talk to somebody who has been there, and you have. you've logged 54 days in space during four missions. how does space travel affect you physically and mentally? >> well, the physical effects are pretty significant. i mean, you lose blood volume, your immune system gets depressed. you start to lose bone mass after spending some time in space. we have astronauts that have had issues with their optic nerves. then there's the radiation environment. so it has significant physiological effects, and w...