The Boeing CST-100 Starliner, a crew capsule for NASA’s Commercial Crew Program, has been plagued by persistent problems. Its first crewed test flight in June 2024 was cut short by technical failures, including helium pressurization leaks and multiple thruster malfunctions. NASA ultimately elected to return Starliner to Earth without its crew, keeping the astronauts aboard the station for safety. With those problems unresolved, NASA now says the capsule will remain grounded until around 2026, and its next mission will likely be uncrewed.

Technical Setbacks and Grounding

According to NASA, During its June 2024 Crew Flight Test, Starliner suffered serious propulsion issues. Multiple helium leaks were detected in the service module’s pressurization system, and five of the capsule’s 28 fine-control thrusters failed during approach to the ISS. NASA and Boeing extended the crew’s station stay while engineers traced the problems to thermal and seal failures in the thruster “doghouse” enclosures.

Ultimately NASA decided to bring Starliner back to Earth empty, concluding the test without its astronauts aboard. Boeing and NASA have since conducted extensive ground testing to validate fixes: engineers at NASA’s White Sands facility are firing thrusters in varied sequences to refine thermal models, and Boeing has added new insulation shunts and thermal barriers in the thruster housings to prevent overheating.

Future of the Starliner Program

Boeing’s delays have reshaped NASA’s Commercial Crew plans. NASA officials say Starliner may even fly one more uncrewed test before carrying astronauts. Starliner development is now billions over budget: its original $4.2 billion contract has grown by roughly $2 billion in extra costs. Meanwhile, SpaceX’s Crew Dragon has flown 11 ISS crew missions and its NASA contract has climbed toward $5 billion amid extra flights added while Starliner lagged. NASA still views Starliner as a critical backup to Dragon and aims to certify it for crew rotations by late 2025 or early 2026.