What happens to your body when you're in outer space?

Jacqueline McCleary, assistant physics professor at Northeastern University, says the term for the effects of being in space are summed up by the acronym RIDGE, which stands for radiation, isolation and confinement, distance from Earth, gravity fields, and hostile/closed environments.

All those factors can affect a person, McCleary says.

"All space flight involves being in a microgravity environment," she says. "Astronauts essentially … are perpetually falling in an elevator."

'Motion sickness on steroids'

The longest space mission on record was about 476 days, McCleary says, so knowledge on the long-term effects are limited and research is still ongoing.

Wilmore and Williams blasted off from Florida on June 5. So, as of Sept. 20, they have been in space 107 days.