NASA said on Thursday it expects to announce on Saturday its decision on whether the two astronauts who rode Boeing’s glitchy Starliner spacecraft to the International Space Station will need a SpaceX vehicle to return to Earth.

“NASA’s decision on whether to return Starliner to Earth with astronauts aboard is expected no earlier than Saturday, Aug. 24 at the conclusion of an agency-level review,” the space agency said in a statement.

Starliner launched its first two astronauts into space in June as a crucial test before it can receive NASA approval for routine flights. But what was supposed to be an eight-day mission docked to the ISS has been drawn out by months after the capsule sprang leaks and some of its thrusters failed.

NASA administrator Bill Nelson will attend the agency-level review, the statement said. Boeing for months has sought to quell NASA fears about the Starliner issues with new test data the company has claimed validates the spacecraft’s safety for astronauts.

NASA is weighing that data against its low appetite for risk in the mission, one of four Starliner flights since 2019 to suffer mishaps.

The agency has prepared a backup plan to make two seats available on an upcoming SpaceX’s Crew Dragon mission that the Starliner crew - veteran NASA astronauts Butch Wilmore and Suni Williams - could use.

If NASA exercises the SpaceX backup plan, Wilmore and Williams would not come home until that mission’s conclusion in February 2025, and Starliner would attempt to return to Earth empty.

If NASA decides Starliner is safe for the astronauts, the capsule would fly them home itself much sooner, likely within the next month to free up the ISS docking port for the SpaceX mission.

The upcoming NASA decision is a nerve-wracking moment for Boeing, which has struggled to develop Starliner and compete with SpaceX’s similar but more experienced Crew Dragon. Boeing has taken $1.6 billion in losses on the Starliner program, securities filings show.