Because NASA rotates space station crews approximately every six months, this newly launched flight with two empty seats reserved for Wilmore and Williams won’t return until late February. Officials said there wasn’t a way to bring them back earlier on SpaceX without interrupting other scheduled missions.

NASA decided using the Boeing Starliner capsule to bring Butch Wilmore and Suni Williams back to Earth was too risky following a string of technical glitches on their outwards journey.