NASA is considering keeping its two astronauts there until February as they make their way to the International Space Station after the Boeing spacecraft encountered problems during the flight.

NASA said Wednesday it was still considering options for how to return astronauts Butch Wilmore and Suni Williams safely to Earth and that no plans had been made yet, but officials acknowledged more openly than before that it may decide to use a SpaceX capsule instead.

“Our first option is to return Butch and Suni aboard Starliner,” Steve Stich, NASA’s commercial crew program manager, said at a press conference Wednesday. “But we are making the necessary plans to ensure we have other options and are working with SpaceX to ensure we are prepared to respond.”

Wilmore and Williams arrived at the space station on June 6 on the first crewed test flight of Boeing’s Starliner spacecraft. The original plan was to stay in space for about a week. But a problem with five of Starliner’s thrusters caused the spacecraft’s propulsion system to leak helium, leaving the astronauts stranded in space for more than two months while engineers on the ground gather data on the problem and attempt to troubleshoot it.

The mission was planned as the final step before Boeing is approved to launch regular crewed flights to the ISS, a process whose fate is now up in the air.

NASA gave no indication of when astronauts might return in the Boeing capsule, but Stich said a final decision would need to be made by mid-August.

Meanwhile, the launch of one of SpaceX’s Dragon spacecraft, which was scheduled to deliver a new crew of four to the space station later this month, has been postponed to give NASA and Boeing more time to address issues with the Starliner.

SpaceX mission (Crew 9) NASA officials said they could change plans to send just two crew members into space on the spacecraft instead of four, and use the capsule to bring Wilmore and Williams home.

Ken Bowersox, associate administrator for NASA’s Space Operations Mission Directorate, said there had been disagreements over how to bring the astronauts home safely.

“We have to admit that when we have disagreements, it’s not fun,” Bowersox said. “Those discussions can be painful, but that’s what makes us a good organization, and it helps us make good decisions in the future when we get to that point, and I don’t think we’re that far away.”

If Wilmore and Williams were to return to Earth in a separate spacecraft, mission managers could adjust Starliner’s software to detach it from the space station and return to Earth without a crew member, Stich said.

Boeing officials did not attend the briefing, but a company representative said in a statement that “we remain confident in Starliner’s capabilities and flight principles.”

“Should NASA decide to modify the mission, we will take the necessary steps to prepare Starliner for an uncrewed return,” the statement said.

The thruster problem occurred as Starliner approached the space station in June, forcing a delay in the docking process. Meanwhile, the helium leak was already on mission managers’ radar before launch, who said at the time that the leak was unlikely to affect the mission or the safety of astronauts.

NASA and Boeing engineers have been trying to replicate on-orbit conditions with a test engine at NASA’s White Sands Test Facility in New Mexico, and mission managers have also conducted two “hot-fire” tests in space, in which the capsule’s thrusters were briefly fired while docked to the space station.

Stich said Wednesday that tests showed that small Teflon seals expand under high temperatures, possibly contributing to the thruster failure. When the seals expand, they likely block the flow of propellant to the thrusters, he said.

Further testing is needed to understand the cause of the potential blockage and why it went undetected during the recent hot-fire test. Last week, NASA reported that the thrusters used to steer the spacecraft in orbit and guide it into position before re-entering Earth’s atmosphere appeared to be stable.

“This gives us a lot of confidence in the thruster, but we can’t prove with complete certainty that what we’re seeing in orbit is exactly what we’re replicating on the ground,” Stich said.

The recent Starliner debacle has been a blow to Boeing, especially since the program was already years behind schedule and more than $1.5 billion over budget before astronauts even launched.

Boeing and SpaceX developed the space capsule as part of NASA’s Commercial Crew Program, an effort launched more than a decade ago to help private companies build new spacecraft to carry astronauts to low Earth orbit. The program began after NASA retired the Space Shuttle.

SpaceX has been ferrying astronauts to the International Space Station since 2020.