The return has been delayed by more than a month, and two NASA astronauts will remain aboard the International Space Station until engineers finish working on problems with their Boeing capsule, officials said Thursday.
Test pilots Butch Wilmore and Sunita Williams were scheduled to visit the orbital lab for about a week and return in mid-June, but a thruster failure and a helium leak in Boeing’s new Starliner capsule forced NASA and Boeing to keep them there longer.
Steve Stich, NASA’s commercial crew program manager, said mission managers are not ready to announce a return date. He said the goal is to get Wilmore and Williams back on Starliner.
“We’ll come home when we’re ready,” Stitch said.
Stich acknowledged that backup options are being reviewed. SpaceX’s Dragon capsule is another means of transporting NASA astronauts to and from the space station.
“NASA always has contingency options,” he said.
Engineers completed testing on a spare thruster in the New Mexico desert last week and will take it apart before Starliner docks to try to understand what went wrong. Five thrusters failed as the capsule approached the space station, a day after liftoff on June 6. Four have since been reactivated.
It appears that bad seals are responsible for the helium leak and thruster problems — entirely separate issues — but more analysis is needed. Boeing’s Mark Nappi said the team will test the capsule’s thrusters while docked to the space station this weekend to collect more data.
Each of the 28 maneuvering thrusters can fit in a single arm and weighs 2 pounds (1 kilogram). The capsule also has larger engines for ejecting from orbit at the end of the flight. These are all part of a segment that is discarded before landing, which means there is nothing to study for future flights.
After the space shuttles were retired, NASA hired private companies to fly astronauts to the space station, paying billions of dollars to Boeing and SpaceX.
It was Boeing’s first test flight with a crew on board. An early demo in 2019, an empty flight, didn’t reach the space station because of faulty software, and Boeing repeated the test in 2022. More problems later cropped up.
SpaceX has been carrying astronauts since 2020. SpaceX’s Falcon 9 rockets have been grounded for the past two weeks due to an upper stage failure on a satellite-delivery mission. The longer the stand-down lasts, the more likely it is that upcoming crew flights will be delayed.