NASA and SpaceX will launch a two-person crew on a Dragon that will be the ride home for the Starliner astronauts stuck in space.

SpaceX launched the rescue mission on Saturday with a downsized crew of two astronauts and two empty seats reserved for Butch Wilmore and Suni Williams, who will return next year. The Dragon capsule docked in darkness as the two craft soared 265 miles (426 kilometers) above Botswana.

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.