Two NASA astronauts who flew up to the International Space Station in a Boeing Starliner capsule for a round trip that was supposed to last just over a week will be stuck in space for closer to a year before they can come home. Despite the astronauts’ longer-than-expected stay at the space station, officials have insisted that Suni Williams and Butch Wilmore aren’t stranded in space.

Here’s what we know about the stuck astronauts:

Why are the astronauts stuck in space?

Williams and Wilmore blasted off to the space station in June. Their mission was supposed to take between eight and 10 days, but helium leaks in the capsule’s propulsion system and degraded thrusters, which are important for re-entry, upended plans for bringing the astronauts back to Earth.

“Eight days to eight months or nine months or 10 months, whatever it is, we’re going to do the very best job we can do every single day,” Wilmore told CBS News correspondent Mark Strassmann in September. At the time, they were expected to leave the space station in late February 2025.

The capsule safely returned to Earth in September with no one onboard.

Who are the astronauts who are stuck in space?

Williams turned 59 on the space station in September. She joined NASA in 1998 after serving in the Navy for over a decade, retiring as a captain. As a naval aviator, she logged over 3,000 flight hours in more than 30 different aircraft. At NASA, she had set a record for women with four spacewalks lasting a total of 29 hours, 17 minutes, but it was broken by Peggy Whitson with her fifth spacewalk in 2008.

Wilmore also retired from the Navy as a captain, recording over 8,000 flight hours as a naval aviator. During Operation Desert Storm in Iraq in 1991, Wilmore flew 21 combat missions. He joined NASA in 2000 and accumulated 178 days in space before the Starliner mission. Like Williams, he has also performed four spacewalks, totaling 25 hours, 36 minutes.

Why did the Boeing Starliner crew go to the International Space Station in the first place?

The June launch was the Starliner’s first piloted test flight. NASA has funded the development of the capsule and SpaceX’s Crew Dragon as the space agency looks to stop using Russian Soyuz flights to transport astronauts to and from the space station.

When will the astronauts be able to return to Earth?

On Tuesday, Dec. 17, NASA announced Williams and Wilmore would return to Earth after the agency’s new SpaceX crew arrives at the space station. That won’t happen until late March at the earliest so NASA and SpaceX can have more time to finish a new Dragon spacecraft for the mission, NASA said.

Have other astronauts been stuck in the International Space Station before?

NASA astronaut Frank Rubio and two cosmonauts’ six-month stay on the space station was unexpectedly extended to a year after their Soyuz ship became disabled. A replacement had to be launched up to the trio so they could return to Earth in 2023.

contributed to this report.