Boeing’s Starliner will not return astronauts to the International Space Station until 2028, according to an update from NASA. The delayed timeline follows technical issues during the spacecraft’s crewed flight test in 2024, prompting valve modifications, thermal fixes, and an upcoming uncrewed test flight.
Boeing’s Starliner spacecraft will fly astronauts again in 2028, pushing back crewed missions by several years. NASA announced the updated schedule during a press briefing, detailing plans for an uncrewed engineering evaluation mission ahead of any future human flights to the International Space Station.
Technical Failures and the Path to the 2024 Mishap Classification
The timeline adjustment follows a turbulent period for the commercial crew vehicle. Starliner first launched on an uncrewed mission in December 2019 known as Orbital Flight Test, where an onboard timing system failure left the capsule stranded in the incorrect orbit and prevented it from reaching the orbiting laboratory.
While an uncrewed OFT-2 flight in May 2022 successfully reached the space station, it encountered thruster anomalies along the way. The stakes rose significantly in June 2024 during the Crew Flight Test, Starliner’s first-ever astronaut mission carrying NASA crew members Suni Williams and Butch Wilmore.
Shortly after the spacecraft separated from its rocket, teams flagged helium leaks and the failure of five out of 28 reaction control system thrusters. Although the capsule managed to dock with the station, safety concerns ultimately led managers to return the vehicle empty in September 2024. Williams and Wilmore remained aboard the station for an extended stay, returning home aboard a SpaceX Crew Dragon capsule the following March. NASA formally designated the CFT flight a “Type A mishap,” the most serious kind, in February.
Joint Investigation Findings and Engineering Redesigns
To fix the vehicle, a joint Boeing and NASA team investigated the underlying mechanical failures. Engineers traced the helium leaks to valve degradation caused by exposure to nitrogen tetroxide, the oxidizer used in the propulsion system.
Managers also realized the need to select seals located on the larger end of the tolerance spectrum. According to agency officials, Boeing has implemented all of those changes on the upcoming Starliner-1 vehicle already.
Meanwhile, investigators pinned the crew module thruster anomaly on corrosion caused by residual hydrazine propellant combined with atmospheric carbon dioxide. Boeing instituted operational procedures to flush out the hydrazine and flow a continuous purge to isolate those thrusters from environmental exposure.
Starliner-1 and the Roadmap Toward Certification
The next major milestone for the program is Starliner-1, an uncrewed engineering evaluation flight scheduled to fly in December of this year or January 2027. The mission will gather flight data, test thermal environment improvements, and validate system qualifications.
Because certain modifications cannot be tested until after that uncrewed flight, a significant gap remains before the crewed mission. Following Starliner-1, teams will complete service module thruster valve design modifications focusing on poppet seal extrusion. Boeing will also install new crew module thrusters, updated batteries, and minor parachute system adjustments to boost overall reliability.
Commander Selection and Commercial Crew Expansion
NASA confirmed that veteran agency astronaut Woody Hoburg will command Starliner-2, the crewed flight targeted for mid-2028. No crewmates have been named yet for his team.
Hoburg added that the capsule grants flight crews real capabilities to handle off-nominal situations. At the same time, NASA intends to exercise options for a fifth and sixth flight to the station using Starliner. Agency leadership emphasized a continued commitment to maintaining multiple independent transportation options for low Earth orbit, even as Boeing and United Launch Alliance work to certify the Vulcan rocket to replace the Atlas V after its final flight.