NASA and Boeing are targeting the first half of 2022 to launch the rescheduled test flight of the CST-100 Starliner commercial crew vehicle as engineers continue to investigate a valve problem that postponed the mission two months ago.
In an Oct. 8 statement, NASA said engineers had managed to free all but one of 13 stuck propellant valves in the Starliner spacecraft. Those stuck valves forced the postponement of Boeing’s uncrewed Orbital Flight Test (OFT) 2 mission in early August. The one remaining valve still stuck closed is kept in that state deliberately “to preserve forensics for direct root cause analysis.”
The analysis has yet to determine the root cause for the stuck valves, but NASA stated Boeing believed the most probable cause was interaction between moisture and nitrogen tetroxide propellant, a cause Boeing officials offered in August. The source of the moisture was not included in the statement, which added that “although some verification work remains underway, our confidence is high enough that we are commencing corrective and preventive actions.”
As part of those efforts, Boeing technicians partially disassembled three valves last month and will remove three others in the coming weeks for inspection. Those efforts will determine how Boeing will prepare the spacecraft for a new launch attempt, with options ranging from “minor refurbishment” of components in the Starliner’s service module to replacing the service module entirely.
NASA confirmed in the statement that the next OFT-2 launch attempt will not be this year. “The team currently is working toward opportunities in the first half of 2022 pending hardware readiness, the rocket manifest, and space station availability,” the agency said.
It had already been clear that OFT-2 was unlikely to fly this year because of both the ongoing investigation and other missions to the station. “The timeline and the manifest through the end of the year is pretty tight right now,” said Kathy Lueders, NASA associate administrator for space operations, at a Sept. 21 briefing. “My gut is that it would probably be more likely to be next year, but we’re still working through that timeline.”
Steve Stich, NASA commercial crew program manager, offered the same assessment during an Oct. 6 briefing about the upcoming SpaceX Crew-3 commercial crew mission. “There’s really not an opportunity for OFT-2 to fly this year,” he said. “From a station perspective, it would be some time early next year where a window would open up for OFT-2.”
Starliner would dock at one of two ports, one of which will be occupied by a Crew Dragon spacecraft. The other port will be occupied by a cargo Dragon spacecraft starting in early December, likely until early January. A commercial Crew Dragon spacecraft, flying the Ax-1 mission for Axiom Space, is scheduled to launch Feb. 21 and spend a week docked to the station using that other port.
Stich said at the Oct. 6 briefing it was too soon to narrow down a launch date for OFT-2, given the uncertainties about vehicle readiness. “We really need to get to a root cause on the valve issue on the service module,” he said. “Once we do that, we’ll have a little more certainty on the path forward of when OFT-2 is, and then from that, where CFT is.” CFT, or Crew Flight Test, will be a crewed test flight with up to three NASA astronauts on board that follows OFT-2.
The delays mean that more than two years will elapse between the original OFT mission in December 2019, which suffered several software and communications problems that truncated the flight, and OFT-2. SpaceX, meanwhile, has conducted since OFT the Demo-2 crewed test flight and the Crew-1 and Crew-2 operational missions. The next NASA Crew Dragon mission, Crew-3, is scheduled for launch Oct. 30, with Crew-4 and Crew-5 planned for 2022.
At the briefing, NASA defended Boeing despite those extended delays. “We have not lost confidence in the Boeing team. The team is doing an incredible job of working through the root cause on the valve issue,” Stich said. “I have every bit of confidence that they’re going to figure out what the problem is and they’ll rectify it and we’ll get back to flight really soon.”