SpaceX’s Crew-10 astronauts are set to fly to the space station on March 12. But in many ways, their journey to orbit started on Wednesday.

The astronauts who crewed the Boeing Starliner will have to wait a few more days until making their homecoming after the SpaceX Crew-10 launch scrub.

A launch pad problem prompted SpaceX to delay a flight to the International Space Station on Wednesday to replace NASA’s two stuck astronauts . 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.