As test pilots for Boeing’s new Starliner capsule, Wilmore and Williams expected to be gone just a week or so when they launched from Cape Canaveral on June 5. A series of helium leaks and thruster failures marred their trip to the space station, setting off months of investigation by NASA and Boeing on how best to proceed.

SpaceX aims to launch Crew-10 on Friday. The crew-swap mission will enable NASA’s Butch Wilmore and Suni Williams to return home from the International Space Station.