Senior Science Journalist
NASAAfter an epic nine months in space, Nasa astronauts Butch Wilmore and Suni Williams are finally getting ready to head home.
Their stay on the International Space Station (ISS) was only supposed to last eight days, but their mission was dramatically extended after the spacecraft that they arrived on suffered technical problems.
The pair are travelling back to Earth in a SpaceX capsule along with Nasa astronaut Nick Hague and Russian cosmonaut Aleksandr Gorbunov.
They are expected to undock from the ISS at 05:05 GMT (01:05 EDT) on Tuesday and then splash down off the coast of Florida later that day at 21:57 GMT (17:57 EDT) .
Their landing time, however, could change if the weather conditions are not good enough.
It will mark the end of a mission that has grabbed the world’s attention, however the final stages of their journey won’t be easy.
The SpaceX Dragon capsule will make a fast and fiery re-entry through the Earth’s atmosphere, enduring temperatures of up to 1600C.
As it rapidly slows, the astronauts will experience significant g-forces, about four times the Earth’s gravity.
Finally, four large parachutes will open, allowing the craft to land gently in the ocean.
Helen Sharman, Britain’s first astronaut, said the thrilling ride would be worth it.
“They’re experienced astronauts but they will feel fantastic to be back on Earth. The fresh air is the first thing that gets you,” she told BBC News.
NASAThe saga of Butch and Suni began in June 2024.
They were taking part in the first crewed test flight of the Starliner spacecraft, developed by aerospace company Boeing.
But the capsule suffered several technical problems during its journey to the space station, and it was deemed too risky to take the astronauts home.
Starliner returned safely to Earth empty in early September, but it meant the pair needed a new ride for their return.
So Nasa opted for the next scheduled flight: a SpaceX capsule that arrived at the ISS in late September.
It flew with two astronauts instead of four, leaving two seats spare for Butch and Suni’s return. The only catch was this had a planned six month mission, extending the astronauts stay until now.
The arrival of a replacement crew on Sunday was the final step needed for Butch and Suni’s return – and after a short hand over with the new team, their mission is now at an end.
NASAThe Nasa pair have embraced their longer than expected stay in space.
They’ve carried out an array of experiments on board the orbiting lab and conducted spacewalks, with Suni breaking the record for the woman who’s spent the most hours outside of the space station.
And despite the astronauts being described as “stranded” they never really were.
Throughout their mission there have always been spacecraft attached to the space station to get them – and the rest of those onboard – home if there was an emergency.
Speaking in the weeks before their departure, Butch Wilmore said they weren’t fazed when their mission was extended.
“We came up prepared to stay long, even though we plan to stay short. That’s what we do in human space flight. That’s what your nation’s human space flight programme is all about,” he said.
Suni added that she was sad this would probably be her last mission.
“I think just the fact that we’re living up here, in this very unique place, gives you an amazing perspective,” she said. “I don’t want to lose that spark of inspiration when I leave, so I’m going to have to bottle it somehow.”
NASAThe pair’s mission attracted even more publicity last month after SpaceX CEO Elon Musk said that the astronauts had been left in space for political reasons, and his company could have brought them home sooner.
But Nasa officials said their decisions were based on flight scheduling and the space station’s needs.
Garrett Reisman, a former Nasa astronaut and former director of space operations at SpaceX, said there were good reasons why Nasa didn’t opt for a dedicated rescue mission.
“It wasn’t going to reduce the amount of time that Butch and Suni spent in space by very much – I mean, you’d shave a couple of months off, so the benefit wasn’t that great,” he told BBC News.
“And the cost was high – these crew missions cost hundreds of millions of dollars…. I think Butch and Suni would have been the first ones to say ‘no, that’s not worth it’.”
NASAOnce the astronauts have arrived home, they will be taken to the Johnson Space Centre in Houston, Texas, where they will be checked over by medical experts.
Long duration missions in space take a toll on the body, astronauts lose bone density and suffer muscle loss. Blood circulation is also affected, and fluid shifts can also impact eyesight.
It can take a long time for the body to return to normal, so the pair will be given an extensive exercise regime as their bodies re-adapt to living with gravity. But the first priority for Butch and Suni will be to see their families, friends – and pets.
Garrett Reisman has been in touch with his friend Suni while she’s been in space.
“I had an email from Suni just the other day where she talked about missing sitting on the porch in her house in Maine with the dogs, and smelling the fresh air, feeling the sun on your face,” he told the BBC.
“It’s the basic things about life here on Earth that you miss.”