HomeScienceBoeing to ground Starliner indefinitely until valve issue solved

Boeing to ground Starliner indefinitely until valve issue solved

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Enlarge / Close-up of the Boeing CST-100 Starliner capsule, white room attached, atop the mighty Atlas V launch vehicle at Cape Canaveral’s SLC-41.

Trevor Mahlmann

Boeing said Friday that its Starliner spacecraft will be grounded indefinitely while it continues to investigate problems with the valves in the propulsion system.

In the 10 days since Boeing and NASA scrubbed the launch in Florida, technicians and engineers have sought to open 13 valves that control the flow of dinitrogen tetroxide (NTO) oxidizer through the service module of the spacecraft. There are 24 oxidizer valves in the propulsion system, which is critical both for in-space travel as well as launch emergency escapes.

Boeing has been able to open nine of the valves, said John Vollmer, vice president and program manager of Boeing’s Commercial Crew Program. The other four remain stuck. As a result, the company plans to de-stack the Starliner spacecraft from its Atlas V rocket and move it to the nearby Commercial Crew and Cargo Processing Facility for deeper troubleshooting.

“We made the decision that we were just out of runway and we had to come back to the factory,” Vollmer said during a teleconference with reporters on Friday.

The decision to move Starliner precludes a launch date this month, and it may prevent a launch before 2022. United Launch Alliance, which is providing the Atlas V rocket, will need to focus its attention on NASA’s Lucy mission, due to launch in mid-October. While it is possible Starliner could be readied for a November launch, Vollmer did not sound optimistic.

“It’s probably too early to say whether it’s this year, or not,” he said. “I would certainly hope for as early as possible, and if we could fly this year it would be fantastic.”

More likely, according to sources familiar with NASA’s schedule for traffic to the International Space Station and United Launch Alliance’s manifest for the rest of the year, a launch before February 2022 is unlikely. And that is reliant upon Boeing finding the root cause of the valve issue, identifying a fix, implementing it, and successfully testing it.

According to Vollmer, some of the NTO leaked through seals on the valves. Such leaks are well understood from a physics standpoint, Vollmer said. But then this oxidizer combined with some unanticipated ambient moisture in the cavity around the valve, and this resulted in corrosion that prevented the valves from opening properly.

It is not clear how this moisture got into the spacecraft. While there were thunderstorms when the vehicle was on the Florida launch pad in early August, the ambient moisture did not come from those storms. It could have been due to the humid Florida atmosphere, however. This is one of the issues that Boeing must now investigate alongside engineers from NASA and Aerojet Rocketdyne, which manufactured the spacecraft thrusters.

This is a bitterly disappointing setback for Boeing, which is redoing this orbital test flight at its own expense following an uncrewed Starliner mission in December 2019 that went awry due to software issues. The company’s technicians and engineers worked long and hard after that flight to fix the software, only to have these new hardware problems crop up during launch-day checks on the pad.

It now seems likely that even if Starliner successfully completes its test flight early in 2022, that humans will not fly aboard the vehicle until the second half of next year at the earliest. In the meantime, SpaceX has demonstrated the ability to fly NASA astronauts safely to and from the space station, and the agency will continue to rely on this service for access to space. The fourth Crew Dragon mission carrying astronauts to the station is slated to launch late at the end of October or early November.

“It’s a disappointing day,” said Kathy Lueders, who leads NASA’s human spaceflight program. “I know this is very, very hard on our NASA and Boeing teams.” But, she said, it was important for NASA and Boeing to have the maturity to step back and fix the problem, and not fly before the spacecraft is ready.


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