NASA astronauts Sunita “Suni” Williams and Barry “Butch” Wilmore have been on the International Space Station for more than eight months, even though they initially expected to stay for just about eight days. It’s finally time to come home, and their replacements have arrived.

A relief crew docked to the ISS just after midnight ET on Sunday after two days of delays getting off the ground, the first due to a hydraulic system issue with a ground support clamp arm for the SpaceX Falcon 9 rocket, the second due to weather. But on Friday, at 7:03 p.m. ET, Crew-10, consisting of NASA astronauts Anne McClain and Nichole Ayers, Japan Aerospace Exploration Agency astronaut Takuya Onishi and Roscosmos cosmonaut Kirill Peskov launched on their journey to the ISS. And on Sunday, the SpaceX Dragon spacecraft docked to the orbiting complex at 12:04 a.m. ET, while the station was roughly 260 miles over the Atlantic Ocean.

Read more: NASA Crew-10 Astronauts Launch to ISS on SpaceX Rocket

Now, there will be a two-day handover period, and then Williams, Wilmore, NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov will be on their way back to Earth. They could be on their return trip as early as March 19.

On March 7, Williams turned over command of the ISS to Roscosmos cosmonaut Alexey Ovchinin as she prepared to return home.

‘We’re not stuck’

Williams told PBS NewsHour recently that they don’t feel abandoned by NASA.

“Obviously, there’s a lot of discussion about it, so maybe people could conceive that that’s the way we are, but we’re not stuck,” she said. “We’re part of a bigger process, right?”

When asked about the practicalities of suddenly being in space much longer than anticipated, without extra supplies, Wilmore said that it wasn’t a problem.

“We did launch with fewer clothing, if you will, and that was intentional,” he said. “We brought up some extra gear that needed — the space station needed. We brought it up with us. So we took some of our clothes off. We were only going to be here a week or so.

“But we made do. It was no big deal, honestly. The space station program plans for multiple contingencies. We stockpile food to last four months beyond what is expected, at a minimum. Some — most times, it’s longer than that, food and other amenities, wet wipes, everything that you need up here.”

Wilmore told PBS that he can talk to his family from space, noting that he not only talks with his two daughters but to the boyfriend of his youngest daughter.

“As a dad to daughters, that’s my responsibilities,” he said.

Read more: NASA’s First Interactive Twitch Stream Shows How Much Astronauts Love Coffee

Record spacewalk

Because their stay was extended, Williams set a record. She went on a 5-hour, 26-minute spacewalk with Wilmore and, with that walk, surpassed the record set by a woman for time spent on spacewalks. According to Space.com, Williams now has 62 hours, 6 minutes of spacewalking, surpassing former astronaut Peggy Whitson, who had 60 hours, 21 minutes.

On this most recent spacewalk, the two worked to finally remove a faulty radio-communications unit, one that astronauts on two previous spacewalks couldn’t remove.

Williams previously teamed up with astronaut Nick Hague for a spacewalk on Jan. 16. On that spacewalk, Williams and Hague replaced a rate gyro assembly that helps maintain the orientation of the orbital outpost, NASA said. The astronauts also installed patches to cover damaged areas of light filters on the Neutron star Interior Composition Explorer X-ray telescope, replaced a reflector device on one of the international docking adapters and checked access areas and connector tools that astronauts will use for future Alpha Magnetic Spectrometer maintenance.

Who are the astronauts?

Wilmore, 61, and Williams, 58, are veteran astronauts, naval officers and former test pilots. Williams has been a NASA astronaut since 1998, and Wilmore since 2000. Both have plenty of experience in space.

Williams is the former record holder for the most spacewalks by a woman (seven) and the most spacewalk time by a woman (50 hours, 40 minutes), and in 2007, she ran the first marathon by any person in space.

In 2009, Wilmore piloted the Space Shuttle Atlantis on its mission to the ISS, and in 2014, he was part of the ISS crew that used a 3D printer to manufacture a tool — a ratchet wrench — in space, the first time humans manufactured something off-world.

What was their original mission in space?

Wilmore, as commander, and Williams, as pilot, traveled to the ISS on a 15-foot-wide, Boeing-made capsule called Starliner. They launched on June 5 and docked with the ISS on June 6. NASA hopes Starliner will give the organization a new way to get crews to and from the ISS, and the fact that it’s Boeing-made is another sign that NASA is starting to lean on the private sector for its human spaceflight options, The New York Times reported.

Wilmore and Williams’ ISS mission was supposed to last a mere eight days, during which they’d test out aspects of Starliner and see how it operates with a human crew in space. But due to complications with Starliner, the two astronauts are still up there.

How did they get stuck in space in the first place?

The Starliner was delayed in May due to a problem with a valve in the rocket. Then engineers had to fix a helium leak. That’s all bad news for Boeing. It’s competing with SpaceX, which has been transporting astronauts to the ISS since 2020, making over 20 successful trips to the space station.

On June 5, Starliner finally launched atop an Atlas V rocket, but some problems came along with the launch. NASA announced that three helium leaks were identified, one of which was known before flight, and two new ones. In addition to the leaks, the crew had to troubleshoot failed control thrusters, though the craft was able to successfully dock with the ISS. 

SpaceX has had failures too. A Falcon 9 rocket exploded on the launchpad in 2016. In July of this year, a Falcon 9 rocket experienced a liquid oxygen leak and deployed its satellites in the wrong orbit, The New York Times reported. Additionally, a Falcon 9 rocket in late August lost a first-stage booster when it toppled over into the Atlantic Ocean and caught fire.

But that said, SpaceX has more than 300 successful Falcon 9 flights to its credit. 

Stuck in space: A timeline

• May: Starliner launch delayed due to a problem with a valve in the rocket, and then a helium leak.
• June 5: Starliner launches with Williams and Wilmore on board.
• June 6: Starliner docks with ISS despite dealing with three helium leaks and failed control thrusters.
• Sept. 6: Starliner departs ISS and lands in New Mexico, leaving Williams and Wilmore behind.
• Sept. 28: SpaceX Crew-9 mission launches with Hague and Gorbunov on a Dragon spacecraft.
• Sept. 29: SpaceX Dragon docks with ISS.
• Dec. 17: NASA announces the launch of four crew members to the ISS will be delayed from February to late March.
• March 12: Crew-10, NASA astronauts, Anne McClain and Nichole Ayers, Japan Aerospace Exploration Agency astronaut Takuya Onishi and Roscosmos cosmonaut Kirill Peskov, were delayed by a day, then again the following day.
• March 14: Crew-10 launched on their 28-hour journey to the ISS. 
• March 16: Crew-10 arrived just after midnight Sunday. Now, there will be a two-day handover period.
• March 19: SpaceX Dragon spacecraft is expected to depart the ISS and return to Earth with Williams, Wilmore, Hague and Gorbunov.