NASA and Boeing held a mission briefing to discuss the ongoing challenges with the Starliner spacecraft, including issues with thruster performance, helium leaks, and propellant vapor degradation. The teams are working together to address these concerns and ensure a safe return for the spacecraft's crew, Butch and Sunny. After nearly two months of postponement, there is still no return date for Boeing's stranded Starliner astronauts, who have been stuck on the International Space Station (ISS) since June after their spacecraft developed multiple issues, NASA has announced.
Boeing Starliner approaching ISS for docking Credit: NASA
Butch Wilmore and Sunita Williams rode to orbit in Boeing's spacecraft following years of delays, successfully blasting off on Starliner's inaugural crewed flight from Florida's Cape Canaveral Space Force Station on June 5. They were scheduled to stay a week in orbit.
But during the flight the spacecraft suffered a series of issues, including five helium leaks and five failures of its reaction control system (RCS) thrusters, forcing engineers to troubleshoot issues on the ground. This extended the two astronauts' stay aboard the International Space Station (ISS) to the current 50 days.
The briefing revealed that testing at the White Sands facility showed thrusters healthy for emergency return, but further analysis is needed to understand the impact of prolonged exposure to propellant vapor on the seals. A hot fire test is planned to verify thruster performance and helium system stability.
The teams are also evaluating the impact of a bulge in the Teflon seal on thruster flow and are considering eliminating manual flying between undock and deorbit burn to reduce stress on the thrusters.
NASA and Boeing are working together to address the issues, including analyzing past tests, planning future actions, and collaborating with suppliers to find a resolution. The teams are also reviewing thruster data and planning for an agency return review.
The briefing highlighted the importance of in-flight testing for understanding thruster degradation and thermal issues and the need for potential modifications in thruster usage or flight control system for future flights.
Upcoming milestones and tasks include dissecting the poppet to ensure seal integrity, hot fire testing, and presenting part two of the flight rationale to NASA. The teams are also preparing for a detailed risk assessment model presentation and discussing the health of OMAC thrusters, which play a crucial role in the Starliner mission.
"We don't have a major announcement today relative to a return date," Steve Stich, the program manager for NASA's Commercial Crew Program, said at the news conference on Thursday (July 25). "We're making great progress, but we're just not quite ready to do that." NASA officials have previously said that the spacecraft has enough fuel to remain in orbit until mid-August at the latest.
Stich said that NASA and Boeing may perform a test fire of the spacecraft "as early as next week." Following this review, Stich added, an undock time will be announced.
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Hoping for a safe return of the crew. Old enough to remember the loss of Challenger. Brave souls all...