After a three-month stay at the International Space Station (ISS), Boeing’s CST-100 Starliner will return to Earth uncrewed on Sept. 7. This decision comes after the spacecraft experienced numerous technical issues, including helium leaks and problems with five reaction control system thrusters, which prevented the spacecraft from demonstrating its ability to safely return astronauts from orbit.
Originally, Starliner was to remain at the ISS for only eight days, returning with NASA astronauts Butch Wilmore and Suni Williams. However, after discovering the technical issues, NASA repeatedly extended the stay while engineers worked on the thruster problems. Finally, NASA determined it was too risky to have astronauts on board for the return journey, due to uncertainty about the thruster's performance during crucial maneuvers.
The Starliner will perform a fully autonomous return, although ground controllers will have the ability to intervene and remotely command the spacecraft if needed. The uncrewed departure will free up a docking port for the next crew rotation mission, Crew-9, scheduled to launch on a SpaceX Crew Dragon as soon as Sept. 24.
NASA plans to fly only two astronauts on Crew-9, reserving seats for Wilmore and Williams for their return to Earth when Crew-9 ends in February 2025. NASA has not yet announced which of the original four Crew-9 members will be retained.
Boeing has not commented on the Starliner's return or other aspects of the commercial crew program since NASA's decision, beyond a brief statement on Aug. 24. “Boeing continues to focus, first and foremost, on the safety of the crew and spacecraft. We are executing the mission as determined by NASA, and we are preparing the spacecraft for a safe and successful uncrewed return.”