Interview: Kevin Fong, Author Of 'Extreme Medicine' : NPR

Interview: Kevin Fong, Author Of 'Extreme Medicine' : NPR: [Due to lack of gravity] they experience [the] wasting of their bones, wasting of their muscles, deconditioning of their heart ... They have problems with their hand-eye coordination. It seems that the apparatus in your inner ear that detects acceleration — that helps you with your day-to-day hand-eye coordination — also gets pretty messed up up there, and so they have problems tracking moving objects with their eyes, and ... they feel pretty sick. In fact, most rookie astronauts feel sick or are sick in the first 24-48 hours of flight. So when you see them up there on-camera, waving and smiling at you, you have to know that underneath that is a lot of discomfort for lots of them.