Two astronauts relinquished their seats on a four-person spacecraft so that their colleagues could return to Earth from the ISS, where they’ve been stuck since June.

A SpaceX Crew Dragon space capsule, which is due to bring home stuck astronauts Butch Wilmore and Suni Williams next year, arrived at the International Space Station (ISS) on Sunday, according to NASA and SpaceX.

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.

NASA astronaut Nick Hague and Russian cosmonaut Aleksandr Gorbunov took off inside a SpaceX Crew Dragon from Cape Canaveral, Florida, just after 1 p.m. on Saturday. The Crew-9 capsule docked with the ISS on Sunday at roughly 5:30 p.m. Eastern time and Hague and Gorbunov entered the ISS about 90 minutes later.

The craft will return Butch Wilmore and Suni Williams - stranded since June - to Earth.

The SpaceX capsule will eventually bring home Butch Wilmore and Suni Williams, the NASA astronauts who piloted the Boeing Starliner test flight.