• Two astronauts have been stuck on the space station after their Boeing spaceship had engine issues.
• Now, their return is being delayed another month to give SpaceX time to process a new spaceship.
• NASA and SpaceX are using the new ship, instead of a refurbished one, to expand SpaceX's fleet.

Two astronauts have been stuck on the International Space Station for months because of issues with Boeing's new Starliner spaceship.

Now, they'll have to stay just a bit longer because SpaceX needs extra time to prepare its Crew Dragon spaceship.

Butch Wilmore and Suni Williams were set to finally come back to Earth in February. Now the earliest they can return is in late March, NASA announced in a blog post on Wednesday.

While one month is not a terribly long delay by regular NASA mission standards, the extra time in orbit is significant considering Wilmore and Williams launched into space for a roughly eight-day mission way back in June.

SpaceX needs extra time to process a new spaceship

SpaceX's Crew-10 mission, originally scheduled for February, is supposed to relieve Wilmore and Williams and allow them to finally return home.

NASA and SpaceX recently decided, though, to use a new Dragon spaceship rather than a used, refurbished one for that launch, according to NASA's blog post.

The new spaceship will need extra time after it ships to SpaceX's processing facility in Florida in January. That's why NASA pushed back the launch date.

"Fabrication, assembly, testing, and final integration of a new spacecraft is a painstaking endeavor that requires great attention to detail," Steve Stich, the manager of NASA's Commercial Crew Program, said in a statement.

This was "the best option for meeting NASA's requirements and achieving space station objectives for 2025," the blog post said.

SpaceX has reused Dragon spaceships for NASA missions in the past. However, a NASA spokesperson told BI that certifying the new spacecraft will expand the company's Crew Dragon fleet to five human-rated spaceships, for both NASA and private missions.

In a statement sent in an email, the spokesperson said that Wilmore, Williams, and their crewmate Nick Hague were "supportive of the path forward."

They added that the three astronauts "understood the possibilities and unknowns, including being aboard station longer than planned."

SpaceX did not immediately respond to a request for comment.

SpaceX to the rescue

The question of how Wilmore and Williams would get back to Earth arose soon after their launch.

As their newly-minted Boeing Starliner ship approached the ISS in early June, it experienced engine issues that raised NASA officials' eyebrows.

After weeks of testing and deliberating, NASA decided to send the Starliner back to Earth empty. Officials weren't confident enough that it was safe.

Meanwhile, Wilmore and Williams stayed on the space station. NASA reassigned them to its next mission with SpaceX, called Crew-9. They would have a ride home on that spaceship. Two other astronauts gave up their SpaceX seats to make room for the Boeing duo.

The catch was that Wilmore and Williams would have to serve the same six-month shift as the rest of Crew-9. They've been conducting experiments and maintenance on the ISS just like everyone else, with the promise of coming home in February.

Now, they'll have to wait another month.

"We appreciate the hard work by the SpaceX team to expand the Dragon fleet in support of our missions," Stich said in the Wednesday statement, adding his appreciation for "the flexibility of the station program and expedition crews."