The crew-swap mission will enable NASA’s Butch Wilmore and Suni Williams to return to Earth from the International Space Station.

According to former NASA astronaut Leroy Chiao, Sunita Williams and Butch Wilmore might experience trouble in walking as and when they return to Earth.

The four newcomers — representing the U.S., Japan and Russia — will spend the next few days learning the station’s ins and outs.