As astronauts Butch Wilmore and Suni Williams acclimatize to Earth, the effects of being stranded in space for nine months, and their recovery, will give scientists a chance to improve preparations for long distance flights.

Nine months in space can permanently alter the body, leaving astronauts with possible long-term health effects.

NASA’s Suni Williams and Butch Wilmore have returned to Earth from a weeklong mission at the International Space Station that turned into an unexpectedly extended stay.