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.

It's possible SpaceX attempts another launch on Thursday, which would pave the way for the astronauts to return to earth.

A launch pad problem has forced a flight delay 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.