Two astronauts sent on an 8-day mission may have to wait until 2025 to return from the International Space Station (ISS), NASA officials have announced.

The Boeing Starliner capsule, which sent them into orbit at the beginning of June, is currently unable to return them safely to Earth. The American agency could therefore call on Elon Musk and his company SpaceX, but if Starliner cannot make it back from the ISS, the duo could return on SpaceX’s Crew Dragon in February 2025.

“We could take either path,” Ken Bowersox, the associate administrator for NASA’s space operations mission directorate, said. “And reasonable people could pick either path depending on where their view is on, on our position and the uncertainty bound that we have for the data that we’ve got on the thruster system, on the propulsion system.”

According to Fox16, Starliner launched its test crew mission on June 5, after a series of delays caused by leaks and thruster issues. This marked the first time the company launched a crewed mission to space.

While trying to dock at the ISS in June, five of the 28 thrusters went down. The mission was initially supposed to last about 8 days, but there is still no official return date for Wiliams and Wilmore after the issues.

NASA said that they have been in talks with SpaceX for them to leave two vacant seats on their upcoming Crew Dragon launch in September, setting them up for a possible return next year. NASA’s commercial crew program manager Steve Stich said the best option is still to return the astronauts on the Starliner.

“You know, our prime option is to return Butch and Suni on Starliner,” Stich said. “However, we have done the requisite planning to make sure we have other options open, and so we have been working with SpaceX to ensure that they’re ready to respond on Crew Nine for a contingency of returning a Butch and Suni on Crew Nine if we need that.”

“We have set up the Dragon for Crew Nine to have flexibility, to have only two passengers fly up on that flight, and then we could return four crew members in the February 2025, timeframe,” he added.