WASHINGTON - NASA officials stated on September 21 that Boeing's CST-100 Starliner commercial manned aircraft was postponed in August due to valve problems, and it is unlikely that it will take place before sometime next year.

In a call with reporters about NASA’s organizational changes, Kathy Lueders, deputy director of the New Space Operations Mission Council, said that engineers are still working to determine why the valve in the propulsion system of the Starliner spacecraft was stuck, delaying an unmanned test flight. It was originally scheduled to be held in early August.

Boeing abandoned the test flight called Orbital Flight Test (OFT) 2 conducted in its August window and grounded it on August 13. The company unloaded the Starliner spacecraft from its Atlas 5 rocket and sent it back to the Space Center at the Kennedy Airport production facility for further investigation.

"The team is still troubleshooting," Lueders said. Boeing officials said last month that nitrous oxide propellant leaked through the Teflon seal on the valve and interacted with moisture on the "dry" side of the valve, producing nitric acid that would corrode the valve and cause the valve to close.

Lueders said the workers have studied the dry side of the valve and are now considering removing the valve to inspect the "wet" side. She said that there will be a "decision point" in the next few weeks, which is whether to repair this service module or use a new service module to perform OFT-2 tasks.

She doubted whether the OFT-2 mission could be completed before the end of this year. "The timetable and list as of the end of this year are now very correct," she said. "My intuition is that next year is more likely to happen, but we are still working hard to complete that timetable."

The start of the mission depends not only on the preparation of the vehicle, but also on the availability of the docking port of the space station. Commercial passenger vehicles such as Starliner can stop at one of the two ports of the station. Two ports are currently in use, one is used by the Crew Dragon spacecraft for Crew-2 missions, and the other is used by the Cargo Dragon spacecraft.

The Crew-2 spacecraft will be replaced by the new Crew Dragon, which will perform the Crew-3 mission in November. When the cargo dragon or the crew dragon does not use another docking port, the OFT-2 mission will have to fly, and it is currently planned to fly the commercial Ax-1 mission to the space station in early 2022.

The continued delay of the OFT-2 mission will postpone the manned flight test mission with three NASA astronauts to the space station and subsequent operational missions.

"I don't think we are ready for the exact time to officially resolve the OFT-2 mission," Lueders said. "I think the team has made a lot of progress in further troubleshooting, and I absolutely know that we will solve this problem before the crew takes off."

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