Boeing’s second chance to test launch its troubled astronaut capsule to the International Space Station was delayed again, possibly until the middle of 2022, as NASA and the aerospace giant go to new lengths to investigate problems with the spacecraft’s fuel valves.

The Starliner capsule came within hours of launching to the space station on an Atlas 5 rocket in August, as part of a 10-day test mission without humans on board.

It was part of a NASA program known as Commercial Crew, which is designed to stimulate the private development of two competing space capsules capable of ferrying astronauts to and from the International Space Station.

SpaceX received its own contract worth roughly $3 billion, and its Crew Dragon capsule carried out its first uncrewed flight to the space station in 2019.

Boeing’s first attempt to launch an uncrewed Starliner in December 2019 failed to reach the space station because of dozens of software glitches, some of which had to be repaired while the spacecraft was in orbit.

The company spent 18 months making roughly 80 corrections to both the spacecraft and the Starliner team’s internal safety culture, as mandated by NASA, and Boeing took a $410 million charge in 2020 to launch Starliner again for another uncrewed test.