Boeingâ€™s Starliner spacecraft has been recalled to the factory because of sticky valves.
The Starliner is designed to take NASA astronauts to and from the International Space Station, and was already years behind schedule. Earlier problems with the spacecraft have added financial losses to Boeingâ€™s balance sheet.
Fridayâ€™s announcement means that the capsule will be taken off the Atlas 5 rocket at the Cape Canaveral Space Force Station in Florida and returned to Boeingâ€™s factory located nearby at NASAâ€™s Kennedy Space Center. The scheduled crewless demonstration flight it was to complete will be delayed for at least two months, and possibly into next year. And that will further postpone Boeingâ€™s first flight with astronauts aboard.
â€œThis is obviously a disappointing day,â€ Kathy Lueders, NASAâ€™s associate administrator for human exploration and operations, said during a telephone news conference. â€œBut I want to emphasize that this is another example of why these demo missions are so very important to us.â€
A similar spacecraft, Crew Dragon, built for NASA by SpaceX, has already carried astronauts to the space station three times since last year, and may carry two more crews to orbit before the end of 2021.
Starliner was originally supposed to lift off to the space station without astronauts aboard on July 30 â€” a repeat of an earlier flight to verify the spacecraftâ€™s systems â€” and then return to Earth about a week later. But that launch date was pushed back after a mishap at the space station, when a newly docked Russian module, Nauka, inadvertently fired its thrusters and sent the station into a spin.
The next opportunity to launch was Aug. 3, and the rocket with Starliner on top was on the launchpad the night before when a severe thunderstorm rolled through. During the countdown the next day, 13 valves used in Starlinerâ€™s propulsion system failed to open, and the launch was called off.
In the days of troubleshooting that followed, engineers were able to get nine of the 13 valves working but four remained stuck.
â€œIf we were able to free them all, we would have been in a good operational condition,â€ said John Vollmer, Boeingâ€™s vice president and program manager for Starliner. â€œThatâ€™s what we were shooting for, but obviously, with not getting all the valves, we made the decision that we were just out of runway and we had to come back to the factory.â€
Mr. Vollmer said the problem occurred among 24 valves that control the flow of nitrogen tetroxide, a propellant used by Starlinerâ€™s thrusters. Some of the nitrogen tetroxide appears to have permeated through Teflon seals and interacted with moisture on the other side to produce nitric acid, Mr. Vollmer said.
â€œThat nitric acid resulted in some corrosion which resulted in the stiction of those valves,â€ Mr. Vollmer said.
Mr. Vollmer said the valves were unchanged in design from the first launch of Starliner in December 2019. That flight was bedeviled by major software flaws that prevented it from reaching the space station, leading Boeing and NASA to decide that a do-over was necessary before certifying that Starliner is ready to carry astronauts. But the hardware, including the valves, operated nearly flawlessly during the abbreviated 2019 trip.
â€œWe havenâ€™t seen this problem in the past, and weâ€™re seeing it now,â€ Mr. Vollmer said. He said engineers now need to figure out what was different â€” perhaps weather conditions including the thunderstorm drenching, perhaps something in the manufacture of the valves. He said he did not think rain had directly leaked into the valves.
The Starliner launch will now occur after the launch of NASAâ€™s Lucy spacecraft, which will be headed to study Trojan asteroids, which are gravitationally trapped in the orbit of Jupiter. The alignment of planets dictates that Lucy must launch during a three-week stretch from mid-October to early November. If it misses that window, the next opportunity would be next year.
Once Starliner is back at Boeingâ€™s facility at the Kennedy Space Center, engineers will first figure out what they have to take apart to fix the valves. Mr. Vollmer said it was too early to estimate how long the fixes would take or when the spacecraft would get back to the launchpad.
â€œItâ€™s probably too early to say whether itâ€™s this year or not,â€ he said. â€œI would certainly hope for as early as possible. And if we could fly this year, itâ€™d be fantastic.â€