Boeing’s Starliner capsule has just returned to Earth without astronauts, marking the beginning of a new series of NASA investigations.
Starliner departed the International Space Station (ISS) on Friday evening (September 6) and landed successfully in New Mexico shortly after midnight on Saturday (September 7). The landing ended the Crew Flight Test (CFT), Starliner’s first astronaut mission. But no astronaut landed with the capsule on Saturday; Starliner experienced problems with its reaction control system (RCS) engines shortly after the CFT launch on June 5, and NASA decided not to send Williams and Wilmore back on board the capsule.
The duo has a concrete plan for their return home: They will return to Earth in February 2025 aboard a SpaceX Crew Dragon capsule – the one that will fly the company’s Crew 9 mission, which is scheduled to launch to the ISS on September 24. But what will happen next with the Starliner program is a bigger question.
NASA contracted SpaceX and Boeing in 2014 to send astronauts to the ISS and back. Leveraging the experience of its Cargo Dragon spacecraft, SpaceX flew a Crew Dragon test mission to the station without astronauts in 2019 and passed all requirements, allowing the company to conduct its first astronaut test flight the following year. This endeavor was successful, and SpaceX quickly moved on to conducting operational, long-term astronaut missions to the ISS for NASA. The company is in the middle of its eighth such flight and is preparing for its ninth (Crew-9).
Related: NASA astronauts can’t wear Boeing Starliner spacesuits in SpaceX’s Dragon. Here’s why
Starliner, a new design, required some adjustments. Its first mission, an unmanned test flight in December 2019, failed to reach the ISS due to software problems. The capsule’s second attempt to reach the ISS in May 2022 was successful, but some problems with the propulsion system occurred during that flight.
CFT also had problems – namely helium leaks and problems with the engines. (Five of the Starliner’s 28 RCS engines failed while it was tracking the ISS shortly after launch.) The mission was only supposed to last about 10 days, but NASA kept the Starliner attached to the ISS for three months while it analyzed the engine problems and discussed how to fix them.
These problems appear to be related to overheating, a consequence of the frequency of the engines and their placement in heat-trapping shelters on the outside of the spacecraft, known as “doghouses.” Bulging seals and peeling insulation appear to be limiting the flow of fuel to the RCS engines.
NASA and Boeing had hoped that CFT would pave the way for Starliner’s first operational crewed flight. That mission, known as Starliner-1, is tentatively scheduled for August 2025. But it’s too early to say whether Starliner will meet that schedule.
“I think we’ll see where we are in about a month and have a little bit more of an idea of the overall schedule,” said Steve Stich, head of NASA’s Commercial Crew Program, during a post-landing press conference Saturday morning.
This schedule could even include another test flight before Starliner is certified for astronaut missions.
“I would say it’s probably too early to think about exactly what the next flight will look like. I think we want to take the next step and look at all the data,” Stich said.
“We know we have some things we need to work on,” he added. “And we’re going to do that and fix those things and then fly when we’re ready.”
Much of this work will focus on the problem of RCS engine overheating and its containment.
“What we need to do now is look at an engine at White Sands (test facility in New Mexico) and make sure we understand the exact pulse sequences that are causing the heating,” Stich said. “And then in parallel, we need to look at software changes to reduce the number of requests to the engines.”
Teams will also examine whether the thermal blankets in the dog kennels can be removed or modified to keep the engines cooler, he added.
“So I would say that there are actually three different directions of attack,” Stich said.
But there were also many positives to take away from CFT, Stich stressed. Starliner performed very well today in entry, descent and landing, he said, describing the landing at the White Sands spaceport as a “bull’s eye.” And he estimated that despite Starliner’s problems, Boeing was able to achieve 85 to 90 percent of CFT’s mission objectives.
Joel Montalbano, deputy director of NASA’s Space Operations Mission Directorate, also emphasized the positive aspects and tried to put CFT in perspective.
“It’s important to remember: This was a test mission, right?” Montalbano said during the post-landing press conference. “We learned from this mission.”
