Hardware failures, qualification gaps, leadership missteps and cultural breakdowns.
These are some of the factors NASA says spaceflight investigators identified as the reasons why two of its astronauts were stranded on the International Space Station during 2024 and 2025.
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NASA astronauts Butch Wilmore and Suni Williams were supposed to spend a maximum of 14 days on the ISS, but their mission ended up being 93 days after their return spacecraft had to leave without them.
The space agency has now revealed the reasons why Wilmore and Williams became 'stranded' on the Space Station, as was reported in 2025.
Problems with Boeing's Starliner?
On 19 February 2026, NASA released a report of findings from its Program Investigation Team regarding the Boeing CST-100 Starliner Crewed Flight Test.
The test was part of NASA's Commercial Crew Program, which has seen the space agency pivot to the private sector in search of launch systems to carry its astronauts to Earth orbit.
NASA astronauts Butch Wilmore and Suni Williams launched to the International Space Station on board a Boeing Starliner on 5 June 2024. This was Starliner's first crewed test flight to the ISS.
It was originally planned as an 8-to-14-day mission, but the mission was extended to 93 days after "propulsion system anomalies" were identified while the spacecraft was docked to the ISS.
NASA teams then reviewed flight data and conducted a ground test at White Sands Test Facility in New Mexico, USA, and made the decision to return the Starliner without the astronauts on board.
The Starliner spacecraft returned from the space station in September 2024, landing at White Sands Space Harbor.
That left Wilmore and Williams on the Space Station, without their dedicated return vessel.
They would eventually make the journey back home in March 2025, onboard the SpaceX Crew-9 mission.
"The Boeing Starliner spacecraft has faced challenges throughout its uncrewed and most recent crewed missions," says NASA Administrator Jared Isaacman.
"While Boeing built Starliner, NASA accepted it and launched two astronauts to space. The technical difficulties encountered during docking with the International Space Station were very apparent.
"Beyond technical issues, it is clear that NASA permitted overarching programmatic objectives of having two providers capable of transporting astronauts to-and-from orbit, influence engineering and operational decisions, especially during and immediately after the mission.
"We are correcting those mistakes. Today, we are formally declaring a Type A mishap and ensuring leadership accountability so situations like this never reoccur.
"We look forward to working with Boeing as both organisations implement corrective actions and return Starliner to flight only when ready."
What went wrong?
NASA says in February 2025 it chartered an independent Program Investigation Team to look into technical, organisational and cultural contributors to the issues that arose during the test flight.
This report was completed in November 2025.
"Investigators identified an interplay of combined hardware failures, qualification gaps, leadership missteps, and cultural breakdowns that created risk conditions inconsistent with NASA’s human spaceflight safety standards," NASA says, adding it would "accept this as the final report."
There were no injuries related with the Starliner test flight, but because of "loss of the spacecraft’s manoeuvrability as the crew approached the Space Station and the associated financial damages incurred," NASA says it's classifying the flight as a "Type A mishap."
