Four astronauts are gearing up to launch to the International Space Station on Wednesday. Their arrival will, at long last, kick off the process of bringing NASA astronauts Suni Williams and Butch Wilmore home to Earth.

Williams and Wilmore have been the focus of public attention since they launched on the first crewed test flight of Boeing’s Starliner spacecraft in June. Although the plan called for them to stay on the space station for roughly a week, they have now spent nine months in orbit.

The Boeing capsule on which the pair launched encountered several problems on its journey to the ISS, including thruster malfunctions and leaking propulsion. So NASA opted to bring the Starliner craft back to Earth with no one onboard, leaving the two astronauts at the orbiting outpost.

NASA then switched crew rotations around to free up seats on a SpaceX Dragon capsule to enable Williams and Wilmore to return home.

That capsule arrived at the space station on Sept. 29, carrying NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov. The plan calls for Wilmore and Williams to hitch a ride with them at the end of their roughly six-month mission.

That time is approaching as the new crew prepares to launch. Heading to space Wednesday are NASA astronauts Anne McClain and Nichole Ayers, Japanese astronaut Takuya Onishi and Russian cosmonaut Kirill Peskov. They are expected to ride into orbit aboard a SpaceX Falcon 9 rocket on a mission known as Crew-10.

Liftoff is scheduled for at 7:48 p.m. ET from NASA’s Kennedy Space Center in Florida.

The Crew-10 astronauts are set to arrive at the space station Thursday, docking at around 6 a.m. ET. From there, they’ll take over from the four who are wrapping up.