by Douglas Messier
Boeing said on Tuesday that it will delay the second uncrewed flight test of its Starliner spacecraft to the International Space Station (ISS) until sometime in the first half of next year due to ongoing problems with stuck oxidizer valves on the vehicle. A crewed flight test would follow about six months later, with the first commercial mission carrying NASA astronauts in 2023.
The revised schedule could placed the flight about 2.5 years after the first automated flight test in December 2019, which failed to reach ISS due to software and communications problems. The vehicle landed safely after an abbreviated two-day orbital flight.
Boeing and NASA officials discussed the latest delay in the troubled program during a media conference on Tuesday. The space agency expressed confidence in the troubled company, which is developing Starliner to carry astronauts to and from the space station under NASA’s Commercial Crew Program.
Boeing said it believes that 13 of 24 valves on its CST-100 Starliner spacecraft became stuck prior to an August 3 launch attempt after nitrogen tetroxide oxidizer permeated Teflon seals and mixed with excessive moisture and water to form nitric acid. The discovery was made hours before Starliner was set to launch aboard an United Launch Alliance Atlas V rocket from Cape Canaveral Space Force Base in Florida.
Engineers were able to free up nine of the 13 valves on the launch pad, but the other four remained stuck. The Starliner spacecraft was removed from its launch vehicle and returned to the production facility so valves could be removed for analysis.
Boeing is sending two of the troublesome valves to NASA’s Marshall Space Flight Center, where engineers will conduct CT scans on them. Tests on similar valves are also being conducted at White Sands Missile Range.
Boeing said the company is evaluating whether to add heaters to the valves to keep them from getting stuck. Engineers will also add desiccant to vent holes near the valves to prevent moisture from seeping in.
Boeing is already running years behind schedule on Starliner. The delays have put additional pressure on SpaceX, which will fly the first five Commercial Crew missions using its Crew Dragon spacecraft. SpaceX’s third crewed flight is scheduled to lift off on Oct. 31 from NASA’s Kennedy Space Center in Florida.