Boeing’s Starliner tests thrusters on the ISS as NASA considers options for returning astronauts to Earth

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The first Boeing Starliner to take astronauts to space performed a crucial test in space on Saturday (July 27), as the next mission faces a months-long delay.

Tested engineers Starlinerthe reaction control system (RCS) thrusters to prepare for a broader agency review that will assess the spacecraft’s readiness for landing NASA astronauts Butch Wilmore and Suni Williams sometime in August, if all goes according to plan.

“Teams will evaluate test results over the next few days as they work on overall studies ahead of an agency readiness review,” NASA officials said. wrote in a statement on X, formerly Twitter, on Saturday.

Starliner faced problems during the astronaut’s debut docking with the International Space Station (ISS) on June 6th. Although it was successful, helium leaks and problems with five thrusters delayed the event. The Starliner is rated to leave the ISS in an emergency, but before astronauts attempt a nominal departure, engineers are trying to understand why these problems happened.

Figuring out what happened is critical to the readiness of the next mission, Starliner-1, which is expected to spend six months on the ISS in 2025. On Friday (July 28), NASA announced a postponement of that mission to August 2025, past an initial expectation of the beginning of winter.

Related: 50 days after launch to the ISS, Boeing Starliner astronauts still have no landing date

NASA and Boeing have not yet identified how they will solve the Starliner problems, whether by design or by changing the way astronauts fire in future boosters, officials told reporters Thursday (July 27). But in the meantime, Starliner-1 will be delayed to allow “a little more time for Starliner to complete new test mods,” NASA’s Steve Stich told reporters. Stich is NASA’s commercial crew program manager.

Starliner Current space The mission, known as Crew Flight Test (CFT), was initially scheduled to last 10 days. It’s been almost 55 days in space, with astronauts living off a reserve of supplies on the ISS already available for the unexpected. The mission is developmental and as such there was uncertainty with the timeline, NASA and Boeing both stressed before the mission.

On a blog post, Boeing officials said the new RCS test was performed to “confirm the performance of each thruster” in brief bursts, up to 1.2 seconds each. (The RCS has 28 thrusters, but engineers removed one thruster from testing weeks ago because they deemed it unable to fire properly for return to Earth.) Each thruster tested showed maximum thrust ranging from 97% to 102%.

“The helium system also remained stable,” Boeing officials wrote. Wilmore and Williams did not directly fire the thrusters, but remained aboard the Starliner and reported to the ground what they were seeing. (The pair are former U.S. Navy test pilots and have years of experience in aerospace development programs.)

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Ground tests on a booster this month revealed why CFT’s RCS had problems: If fired repeatedly, especially in conjunction with Orbital Maneuvering and Control System (OMAC) boosters, the “doghouses” or isolated bays that housing RCS thruster groups tend to heat up, leading to thrusters eliminating Teflon insulation of their stamps. NASA and Boeing also said this issue could not have been discovered on the ground before the CFT flight.

Starliner is one of two systems funded by NASA to send astronauts to the ISS. The other is the Crew Dragon, built by SpaceX. Crew Dragon first conducted a manned test in 2020, using a design based on SpaceX’s Cargo Dragon ISS vehicle. After testing, Crew Dragon completed 11 ISS missions: 8 half-year missions on behalf of NASA and 3 week-long missions on behalf of Axiom Space.

Crew-9, SpaceX’s ninth operational ISS mission, is scheduled to lift off no earlier than Aug. 18 and Starliner should be home by then, NASA said.