Starliner returns to Earth uncrewed

WASHINGTON — Boeing’s CST-100 Starliner spacecraft successfully landed in New Mexico early Sept. 7, completing the Crew Flight Test (CFT) mission but without any crew on board.

The Starliner spacecraft landed at White Sands Space Harbor in New Mexico at 12:01 a.m. Eastern, about six hours after undocking from the International Space Station. The spacecraft’s reentry and descent appeared to go as planned, and the spacecraft descended under three parachutes before making an airbag-cushioned landing in the desert.

“A safe and successful landing is exactly what we wanted,” said Joel Montalbano, deputy associate administrator for NASA’s Space Operations Mission Directorate, at a post-landing briefing. “We did learn a lot.”

Starliner returned to Earth without astronauts Butch Wilmore and Suni Williams on board. NASA decided Aug. 24 to bring back Starliner uncrewed because of uncertainty in the performance of thrusters that malfunctioned during the spacecraft’s approach to the station June 6.

Starliner undocked on schedule from the station at 6:04 p.m. Eastern Sept. 6. The spacecraft performed a series of burns using its reaction controls systems to back away from the station. That took it outside the “approach ellipsoid” around the station, more than two kilometers from the station, about 20 minutes later, ending joint operations between Starliner and the ISS.

NASA reported no issues with the maneuvers, stating that the spacecraft was on a “perfect trajectory” and that all 27 operational reaction control system (RCS) thrusters were working as expected. That excludes one thruster that malfunctioned during the spacecraft’s approach to the station in June and never recovered.

“OK, she’s on her way home. Congratulations to the undock team,” Williams said after being informed by mission control that Starliner had left the approach ellipsoid.

The return to Earth was not without issues. Steve Stich, NASA commercial crew program manager, said at the post-landing briefing that during the 58-second deorbit burn, two RCS thrusters got hotter than expected but did not fail. He said that controllers had changed software to keep it from turning off thrusters that got too hot during that burn, but didn’t know if the thrusters reached temperatures that would have triggered a shutdown without the software change.

One of 12 separate thrusters on the crew module also did not work in tests before reentry. Stich said those thrusters are a different design from those on the service module and it wasn’t clear why it failed. A redundant thruster, though, did operate normally and did not pose a problem during reentry.

“It was a bullseye landing,” he said, despite a glitch with a navigation computer system that had problem acquiring GPS signals after emerging from the reentry communications blackout.

Path to Starliner-1

With Starliner back on the ground, NASA and Boeing will turn their full attention to fixing the helium leaks and thruster problems that marred the mission. “We’ve been entirely focused this summer on understanding what is happening on orbit, trying to decide if we could bring the crew back or not,” said Stich at a Sept. 4 briefing. “What we need to do now is really lay out the overall plan, which we have not had time to do.”

Neither the agency nor the company have disclosed details about how long that effort will take and if it will require a second crewed test flight, as well as financial details. Boeing has recorded $1.6 billion in charges against the Starliner program so far, a figure almost certain to increase significantly to account for work needed after this mission.

The first operational Starliner mission, called Starliner-1, has already been delayed by NASA from February 2025 to no earlier than August 2025, with the agency also performing preparations for another SpaceX Crew Dragon mission, Crew-11, in parallel with Starliner-1 for that August 2025 opportunity.

At the post-landing briefing, Stich said NASA has been discussing with Boeing next steps to address the thruster problems as well as helium leaks. That includes replacing a seal in the helium pressurization system with one that is both more compatible with the spacecraft’s hypergolic propellants as well as potentially larger. Other teams are looking at changing the thermal environment in “doghouses” on the service module that contain thrusters to reduce heating and modifications to how the thrusters are used.

“That’s the path to Starliner-1,” he said. However, he said later in the briefing that the agency had not decided if they would proceed directly to certification of Starliner and that first operational flight or require another test flight of some kind.

“We’re going to take our time to figure out what we need to do to go fly Starliner-1,” he said. “It’s probably too early to think about what the next flight looks like.”

Both Stich and Montalbano, though, rejected the idea that Starliner’s safe return was a “successful failure” akin to Apollo 13. “We knew going in this was going to be a test mission. We learned a lot,” Montalbano said. “We’re very happy to have the vehicle home. Clearly, we’ve got some work to do.”

Stich noted that CFT still accomplished 85–90% of its mission objectives despite the uncrewed return. “Not having the crew on board, obviously, there are some things we lack,” he said.

However, he added there were no regrets about the decision to return without astronauts on board. “I think we made the right decision to not have Butch and Suni on board,” he said, given the uncertainties at the time about the performance of the thrusters. “It’s awfully hard for the team, it’s hard for me, to sit here and have a successful landing and be in that position, but it was a test flight and we didn’t have confidence in the certainty of the thruster performance.”

Absent Boeing

That post-landing briefing was to have been the first opportunity in more than a month to hear from Boeing officials about Starliner, who last spoke at a briefing about the CFT mission in late July.

A NASA advisory stated that two Boeing executives — John Shannon, vice president of Boeing Exploration Systems, and Mark Nappi, Boeing vice president and commercial crew program manager — would participate. Neither, though, attended the briefing at NASA’s Johnson Space Center.

“We talked to Boeing. They said, ‘Hey, we’d like NASA to take the press brief.’ They deferred to us,” Montalbano said at the briefing when asked about the company’s absence. He said he and other NASA officials talked with Boeing counterparts after the landing. “Boeing is committed to continue their work with us.”

A brief statement from Boeing did not necessarily convey the same level of commitment, though. “I want to recognize the work the Starliner teams did to ensure a successful and safe undocking, deorbit, re-entry and landing,” Nappi said in the statement. “We will review the data and determine the next steps for the program.”

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