What the Starliner Crew Flight Test Taught NASA
Starliner’s first crewed flight reached the space station in June 2024, but propulsion concerns led NASA to return the capsule without its astronauts and bring them home on Crew-9.
Timeline
- June 2024: Butch Wilmore and Suni Williams launched aboard Starliner for its Crew Flight Test.
- August 2024: NASA decided Starliner would return to Earth without its crew.
- March 18, 2025: Wilmore and Williams returned safely aboard SpaceX Crew-9.
Boeing’s Starliner Crew Flight Test launched NASA astronauts Butch Wilmore and Suni Williams to the International Space Station in June 2024. It was the spacecraft’s first flight with people aboard and was intended to test launch, docking, on-orbit operations and return before regular crew-rotation certification. [1][2]
As Starliner approached the station, NASA and Boeing identified helium leaks and problems with reaction-control thrusters. Engineers reviewed flight data, performed ground and in-space testing, consulted propulsion specialists and developed contingency plans. The concern was whether the system’s behavior could be predicted with enough confidence for a crewed return. [1]
NASA decided in August 2024 to return Starliner without Wilmore and Williams. The agency said the uncrewed flight would still gather test data while avoiding additional risk to the astronauts. This was a risk-management decision, not evidence that the spacecraft had failed to reach or leave the station entirely. [1]
Wilmore and Williams remained aboard the station and joined the long-duration expedition. NASA modified the SpaceX Crew-9 plan so the Dragon capsule launched with two open seats for their return. They splashed down safely with Nick Hague and Aleksandr Gorbunov on March 18, 2025. [1][2]
A flight test is designed to expose how integrated hardware, software, procedures and crews behave in the real environment. The mission produced operational experience in maneuvering, docking and emergency protocols as well as detailed propulsion evidence that could not be reproduced completely before flight. [1][2]
The changed return plan also demonstrated why NASA maintains more than one U.S. crew transportation system and contingency capability at the station. Using Crew-9 required schedule and crew-assignment changes, but it gave the agency an alternate route home while Starliner returned autonomously. [1][2]
After the astronauts returned, NASA and Boeing continued addressing the in-flight anomalies and preparing additional propulsion testing toward certification. The mission’s lesson was not that every objective succeeded or failed as a group: docking, crew operations and data collection worked, while propulsion uncertainty prevented the planned crewed landing. [1][2]