NASA, Boeing still working on Starliner return to flight

WASHINGTON — As NASA prepares to launch a new crew to the International Space Station, the agency has yet to decide which spacecraft it will use for the next crew rotation mission.

A SpaceX Crew Dragon is set to launch on a Falcon 9 rocket to the International Space Station on the Crew-12 mission. Liftoff, previously scheduled for Feb. 11, has slipped to Feb. 13 because of forecasts for poor weather at some abort sites along the East Coast.

Crew-12, like its 11 predecessors, will use Crew Dragon. NASA had expected by now to also have Boeing’s CST-100 Starliner available, but problems during Starliner’s crewed test flight in 2024 led the agency to return the spacecraft uncrewed. The two astronauts who flew to the ISS aboard Starliner on that mission returned months later on a Crew Dragon.

NASA announced in November a change to its commercial crew contract with Boeing. The Starliner-1 mission, originally planned as the spacecraft’s first operational crewed flight, will instead carry only cargo. That mission will be followed by three crewed flights, with options for two additional missions.

At the time of the contract modification, NASA said Starliner-1 could launch as soon as April 2026. At a Feb. 9 briefing on the upcoming Crew-12 launch, however, the agency said it had not set a more specific launch date.

“We’re really driven by closing out all the technical work we need to do ahead of that flight,” said Steve Stich, NASA’s commercial crew program manager.

That work includes addressing helium pressurization system leaks observed on the previous mission, as well as thruster malfunctions. Concerns about thruster performance led NASA to decide to return Starliner uncrewed.

Stich said engineers have made “great progress” in resolving the helium leaks by replacing seals that were vulnerable to degradation in the presence of nitrogen tetroxide vapor in the spacecraft’s propulsion system.

Testing of the thrusters is continuing, including hot-firing thrusters on the crew module of the Starliner-1 spacecraft and analyzing data from tests of thrusters housed in enclosures known as “doghouses” on the Starliner service module. Those thrusters experienced malfunctions during the previous flight.

Engineers are developing a model to predict thruster behavior in the doghouses. “When we get through that and get to a point where we’re comfortable predicting thruster performance, then we’ll move forward and look toward a launch date,” Stich said.

Although Starliner-1 will deliver cargo to the station, it will also serve as a test flight. “The purpose of Starliner-1 is to validate the changes that we made,” Stich said. If successful, NASA would then fly astronauts on Starliner-2 for a long-duration crew-rotation mission.

Stich did not offer a more specific launch date for Starliner-1 beyond reiterating a launch no earlier than April. At the briefing, agency officials outlined a busy schedule of upcoming ISS missions, including a Northrop Grumman Cygnus cargo spacecraft launch currently planned for early April.

The timing of Starliner-1 will help determine plans for the crew-rotation mission following Crew-12. Stich said NASA has not yet decided whether that next mission will be another Crew Dragon flight, designated Crew-13, or Starliner-2.

“We want to work through and get through Starliner-1 in the summer timeframe and see where we’re at,” he said. With Crew-12 scheduled to spend about eight months on the ISS, either Crew-13 or Starliner-2 would launch in the fall.

“We have some time to decide,” Stich said, noting that crews are training separately for both Crew-13 and Starliner-2.