Boeing and NASA rolled Starliner and its United Launch Alliance Atlas V rocket off the pad for troubleshooting. Within a few months, investigators had found the likely cause of the valve issue: Nitrogen tetroxide (NTO) oxidizer reacted with moisture in the air, generating nitric acid. The nitric acid then reacted with the aluminum housing of the valves, creating corrosion products that impeded valve function.
That initial diagnosis was on the money, Boeing representatives and NASA officials said during a call with reporters today (May 3). And the mission team has successfully addressed the problem in the time since they added.
“Super proud of the Starliner team and the NASA team over the last eight months,” NASA Commercial Crew Program Manager Steve Stich said during today’s call. “It’s been a hard eight months, I would say, but very fulfilling that we’ve resolved the problem with the oxidizer isolation valves and we’re headed on toward launch.”
The valve fix is a multilayered one. For example, technicians sealed up “a potential moisture path” in the valves’ electrical connectors, Michelle Parker, vice president, and deputy general manager of Boeing Space and Launch, explained during today’s call. The team also now purges moisture out of the valves using nitrogen gas, she said.
Boeing also gave the OFT-2 Starliner a new service module, mating that component to the crew capsule on March 12.
SpaceX also holds a NASA commercial crew contract. Elon Musk’s company recently launched its fourth operational astronaut mission for the agency, which is known as Crew-4. The four astronauts of SpaceX’s Crew-3 flight are currently onboard the station but will return to Earth early Friday morning (May 6), if all goes according to plan.
If all goes according to plan on OFT-2, Starliner will meet up with the ISS about a day after launch and spend five to 10 days docked with the station, NASA officials have said.