The four newcomers — representing the U.S., Japan and Russia — will spend the next few days learning the station’s ins and outs from Butch Wilmore and Suni Williams. Then the two will strap into their own SpaceX capsule later this week to close out an unexpected extended mission that began last June.

The Starliner saga is a step closer to its end with the launch of a SpaceX vehicle that will relieve the astronauts who flew on the Boeing spacecraft.

NASA astronauts Barry Wilmore and Sunita Williams have been stuck in space for nine months, on what was originally going to be an eight-day mission.