NASA said Wednesday that everything is on track for the Starliner capsule to undock from the space station Friday evening. The fully automated capsule will aim for a touchdown in New Mexico's White Sands Missile Range six hours later.

NASA's two stuck astronauts who flew up on Starliner will remain behind at the orbiting lab. They'll ride home with SpaceX in February, eight months after launching on what should have been a weeklong test flight. Thruster trouble and helium leaks kept delaying their return until NASA decided that it was too risky for them to accompany Starliner back as originally planned.

"It's been a journey to get here and we're excited to have Starliner return," said NASA's commercial crew program manager Steve Stich.

NASA's Butch Wilmore and Suni Williams will close the hatches between Starliner and the space station on Thursday. They are now considered full-time station crew members along with the seven others on board, helping with experiments and maintenance, and ramping up their exercise to keep their bones and muscles strong during their prolonged exposure to weightlessness.

To make room for them on SpaceX's next taxi flight, the Dragon capsule will launch with two astronauts instead of the usual four.