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.

The four set to depart are NASA astronauts Anne McClain and Nichole Ayers, Japanese astronaut Takuya Onishi and Russian cosmonaut Kirill Peskov. They're expected to lift off at 7:48 p.m. ET from NASA’s Kennedy Space Center in Florida, aboard a SpaceX Falcon 9 rocket.

The new crew needs to get to the International Space Station before Butch Wilmore and Suni Williams can head home after nine months in orbit.