NASA and SpaceX on Wednesday delayed the launch of a replacement crew of four astronauts to the International Space Station that would have set in motion the long-awaited homecoming of U.S. astronauts Butch Wilmore and Suni Williams.

The quartet will head to the International Space Station for a roughly six-month stay. They'll relieve four other astronauts — NASA's Nick Hague, Suni Williams and Butch Wilmore and cosmonaut Aleksandr Gorbunov, who will come back to Earth a few days after Crew-10 docks.