The first crewed mission of Boeing’s Starliner capsule has been in orbit for more than a month and still has no return date.
Starliner launched June 5 on Crew Flight Test (CFT), carrying NASA astronauts Butch Wilmore and Sonny Williams to the International Space Station (ISS) for a planned one-week stay. The capsule had helium leaks and thruster problems during the trip, but engineers are still looking into what caused them — meaning the Starliner has yet to be cleared for liftoff.
“We’re taking time on the ground to review all the data before making a decision on the possibility of return,” Steve Stich, NASA’s Commercial Crew Program manager, said during a press conference Wednesday (July 10).
However, NASA, Boeing and the two CFT astronauts still have confidence in the Starliner. During a separate media event Wednesday, for example, Wilmore praised the capsule’s capabilities in orbit during operational checks. “The spacecraft performed incredibly well,” he said.
Wilmore also discussed the problems with the Starliner’s Reaction Control System (RCS) thrusters during the ISS chase and how the mission dealt with them.
“We lost an RCS jet, and then another, and then you could tell the thrust, the control, the capabilities were degraded,” he explained. “Fortunately we had practiced and were certified in manual control, so we took over manual control for over an hour.”
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After arriving at the ISS on June 6, Wilmore and Williams integrated into the station’s Expedition 71 crew, which Williams says is now informally called “Expedition 71+.” Wilmore and Williams have assumed day-to-day responsibilities for maintenance and science experiments and have been able to fill the gap on several backlogged tasks on the station. During their mission, the duo also continued their inspections of the Starliner’s many systems and the anomalies they encountered, which are also being scrutinized by Boeing engineers on Earth to determine their cause.
Stitch emphasized the meticulous approach taken to analyze data and reproduce the problems with the spacecraft’s thrusters during testing at NASA’s White Sands Test Facility in New Mexico. One of the advantages of the ISS, he said, is its ability to serve as a temporary orbital “hangar,” providing a unique opportunity to understand the Starliner’s long-term performance in space before it undocks.
In addition to the thruster problems, several helium leaks have been identified in the Starliner capsule. “There were a number of specific actions that were identified from both the helium and thruster anomalies,” Mark Nappi, Boeing vice president and commercial crew program manager, said Wednesday. “There are a little over 30 [actions]of which more than half are currently closed.”
“Regarding the helium leak, we hope to bring it up to the Starliner mission management team for a final decision later this week,” Stich said. Despite those problems, agency officials said the spacecraft is designed to leave the ISS in the event of an emergency, with all but one of its 28 RCS thrusters cleared for use on re-entry into Earth’s atmosphere.
The decision to extend the Starliner mission also provided ground crews with extra time they hadn’t anticipated. According to Nappi, Amy Decker of Starliner’s Office of the Chief Engineer says the additional data they’re getting is “Awesome, in all caps.”
“The more time you have to get more data,” Nappi said, “the more excited [the engineers get].”
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The newest Starliner could return with Wilmore and Williams, Stich said, in mid-August.
“The big driver is the handoff coming up between Crew-8 and Crew-9, which is in mid-August,” Stich said, referring to two SpaceX astronaut missions to the ISS. “So… a few days before [Crew-9] launch opportunity, we’ll have to get Butch and Sunny home on the Starliner.”
Ideally, though, they’ll be home early. “We’re really working to try to track the data and see when is the earliest that we can target takeoff and landing,” Stich said. “I think some of the data suggests, optimistically, maybe it will be until the end of July, but we’ll just follow the data every step of the way and figure out when the right opportunity is to pull off.”
“We really have a lot of confidence in the thrusters as they are today,” Nappi said, referring to a test firing of the thrusters into orbit that the Starliner performed while docked to the ISS.
“What we’re doing is just taking our time to make sure we’ve looked under every rock and every stone and just to make sure there’s nothing else that’s going to surprise us,” Stitch added in response.
CFT follows two previous uncrewed Starliner missions to the ISS. The first, in December 2019, failed to reach the orbiting laboratory after experiencing a number of problems. The second, in May 2022, successfully docked, but also had booster problems.
“We knew there would be some lessons from this flight test,” Nappi said. “We’ve learned a lot from how the hardware works, how our processes work and how we can improve.”
Right now, “there is one thruster that was producing very low thrust that we’re going to disable for the rest of the flight,” Stich explained. The extended stay on the ISS also helps teams prepare the spacecraft for future operational astronaut missions, which are planned to last up to six months, starting with Starliner-1 sometime in 2025.
Tests at White Sands during CFT helped planners look ahead to this first operational mission and how to prevent similar thruster problems from occurring.
According to Stitch, the Starliner’s thrusters were firing more frequently than engineers expected this time.
“What we’re trying to do at White Sands,” he said, “is really reproduce exactly what those pulses were that the thrusters saw, and then understand the heating effect of those pulses, and just be certain that there are no unintended consequences of these impulses.”
Stich said he thinks there is a way to take what the teams observed with the thrusters during CFT to change their requirements for future rendezvous and docking maneuvers. “I think that’s the job ahead of us for Starliner-1,” he said.
While CFT’s mission continues, the focus remains on ensuring a safe return for Wilmore and Williams. “The Starliner is ready to return in an emergency,” Stitch confirmed. The team is working through the process, including a return flight readiness review, to prepare for an eventual Starliner undocking and landing.
