Boeing Starliner Return To Flight Uncertain For 2025

The Boeing CST-100 Starliner may not return to flight this year as the company and NASA work to address the myriad issues exposed during last year's troubled crew flight test (CFT) and a busy launch period for the agency.

"We've got to figure out, manifest-wise, where the Starliner fits. Does it fit best toward the end of this calendar year, the first flight back after CFT, or early next year," Steve Stich, NASA manager for the Commercial Crew Program, said March 7. Among NASA's manifest is a SpaceX mission to boost the altitude of the International Space Station (ISS).

NASA said it plans to work through Starliner vehicle certification toward the end of the year and that the system would be crew capable. No decision has been taken regarding whether it would carry a crew.

The Starliner program is still dealing with the fallout from last year’s CFT mission when NASA decided to return the Calypso capsule to Earth uncrewed over safety concerns after problems surfaced during the spacecraft’s automated approach to the ISS. As the capsule approached the ISS, five reaction control system (RCS) thrusters were sidelined by the flight computer due to what was later determined to be overheating.

The thruster problems followed a series of small helium leaks in the system that pressurizes the Starliner’s RCS jets and larger orbital maneuvering and attitude control (OMAC) system thrusters. Boeing concluded that the leaks resulted from a slight degradation of seals that had been exposed to corrosive propellant.

The problems turned the capsule’s planned seven-to-14-day stay into a three-month saga as NASA and Boeing tried to assess what caused the issue and the best path forward. In the end, NASA opted to keep astronauts Barry Wilmore and Sunita Williams at the ISS rather than return on Calypso. The Crew-10 mission to replace Wilmore and Williams as well as two others is due to launch March 12.

Stich, in a media briefing ahead of the crew return, said the team has addressed about 70% of the issues identified from the prior flight. “We are making good progress on closing out the inflight anomalies and the inflight observations from that.”

Candidate helium-seal replacements are in test, he said.

The team this year also plans to gather data on potential changes to the “doghouses,” or manifolds that house the RCS and OMAC thrusters. NASA will test one of them in its previous setup in a vacuum chamber at White Sands, New Mexico, and hot-fire the engines, he said. That performance data will be compared against modifications, including to thermal blankets and areas to keep the OMAC plume out of the doghouse.

“Once we get through that, those campaigns will know a little bit better what we will do with the flight, in terms of when we go fly the next flight for Boeing,” he added.