The launch of the second uncrewed demonstration mission of Boeing’s CST-100 Starliner commercial crew vehicle will be delayed by months. The delay is necessary in order to fix a problem with the spacecraft’s propulsion system.
Boeing announced August 13 that company would be destack the Starliner spacecraft from its Atlas V launch vehicle and return it to the company’s Commercial Crew and Cargo Processing Facility for “deeper-level troubleshooting.”
The Starliner spacecraft had been scheduled to undertake its second orbital test flight (OFT-2), a short demonstration mission to the International Space Station earlier this month. However, a routine check following an electrical storm found that 13 valves in the spacecraft’s propulsion system were unexpectedly closed.
Following the completion of an initial assessment, the spacecraft was returned to the vertical assembly building still stacked atop its Atlas V launch vehicle. Boeing engineers then reportedly proceeded to employ “mechanical, electrical and thermal techniques to prompt the valves open.”
As of August 12, nine of the valves had been successfully opened. Despite the progress, Boeing was unwilling to commit to a new launch date stating simply that they were working with NASA and United Launch Alliance to “confirm a new launch date when the spacecraft is ready.”
With the spacecraft now slated to be destacked and returned to the company’s processing facility, the launch of OFT-2 is expected to be delayed by several weeks. This will result in a domino effect with the mission making way for the launch of Lucy aboard an Atlas V in mid-October and the launch of the SpaceX Crew-3 mission in late October.
During a press briefing on August 13, NASA and Boeing officials admitted that the flight is likely to slip to 2022.
“It’s probably too early to say whether it’s this year or not,” said John Vollmer, vice president and program manager of Boeing’s commercial crew program. “If we could fly this year, it would be fantastic.”
In the same briefing, Vollmer explained that the cause of the stuck valves had been a reaction between nitrogen tetroxide (NTO), the oxidizer used for Starliner’s thrusters, and unexpected moisture in the system. This combination resulted in a reaction that created nitric acid which in turn corroded the valves causing them to stick in place.
Although Vollmer could not yet identify where the moisture had originated, he stated that the spacecraft could have been exposed to humid conditions on the factory floor or on the launchpad. Either way, one would think that a vehicle that is destined to carry American astronauts to the International Space Station would be able to handle a humid day or two without becoming completely inoperable.