Four astronauts will soon launch to the space station — a flight that will kick off a series of events culminating in the long-awaited return of NASA astronauts Suni Williams and Butch Wilmore.

NASA and SpaceX on Wednesday night scrubbed the Falcon 9 launch of a flight intended to retrieve from the International Space Station astronauts Suni Williams and Butch Wilmore, who have spent nine months in orbit.