The two test pilots for the inaugural crewed flight of Boeing's Starliner spacecraft - NASA's Suni Williams and Butch Wilmore - left Earth for the International Space Station under the assumption their journey would only last about a week.
Months later, after determining that the technical problems the Starliner experienced during the first part of their journey posed too great a risk, NASA decided to return Williams and Wilmore home aboard a SpaceX Crew Dragon capsule.
But that didn't mean the astronauts would get the first flight back to Earth.
A SpaceX Crew Dragon, on a mission called Crew-8, left the International Space Station on Wednesday, but Williams and Wilmore will once again be left behind for the simple reason that they are not assigned to that specific spacecraft.
Notably, the four astronauts assigned to the Crew-8 mission - Matthew Dominick, Michael Barratt and Jeanette Epps of NASA and Alexander Grebenkin of Russia's Roscosmos space agency - have been on the ISS since March 5, about three months longer than Williams and Wilmore.
That's because the Crew-8 team is part of a regular crew rotation in the orbiting laboratory, and routine missions typically last about six months.
The team disembarked from the ISS on Wednesday afternoon and is headed for a landing off the coast of Florida. According to NASA, that will happen at 3:30 a.m. ET on Friday.
Williams and Wilmore, meanwhile, are ordered to return home aboard SpaceX's Crew-9 mission.
NASA and SpaceX even had to reconfigure the Crew-9 capsule and astronaut assignments before the mission launched on September 28 to ensure Williams and Wilmore would have enough room to return home aboard the vehicle when it will complete its ISS mission no earlier than February 2025.
That's just one reason why the duo can't just take the next ride home. Space flights are often more complex - and require more advance planning - than that.
How Williams and Wilmore got here
Williams and Wilmore did not go to the ISS as part of a normal crew rotation.
Instead, the pair ventured into orbit as part of a historic effort: Starliner's first crewed flight. They left on June 4, largely without their own toiletries and other personal comforts, expecting to return to Earth soon.
Williams and Wilmore were then left in limbo by several critical issues, including gas leaks and thruster issues, that plagued their Starliner capsule during the first part of their journey. NASA then chose to leave the capsule - along with Williams and Wilmore - at the ISS while engineers tried to figure out what went wrong.
After weeks of uncertainty, NASA made the call in late August that it would be too risky to return Williams and Wilmore home aboard Starliner.
And the space agency had scrambled to find an alternate route home. This is how NASA came to the decision to put Williams and Wilmore on Crew-9, a mission that had not yet left Earth at the time.
Two astronauts who were scheduled to fly with Crew-9 before the Boeing Starliner debacle - NASA's Zena Cardman and Stephanie Wilson - had to be booted to make room for Williams and Wilmore on the return trip.
The Crew-9 mission then launched with just two astronauts, two empty seats, and some ballst (or dead weight) to balance the physics of flying without a full crew of four. The Crew-9 spacecraft arrived at the ISS on September 29.
Williams and Wilmore, for the record, have now been on the space station for more than 18 weeks.
And Boeing's Starliner finally returned home from space empty on September 6.
How the astronauts will spend their time
So what exactly would Williams and Wilmore do in space for the next four or five months?
When the couple arrived at the ISS, they were guests. But now they're at work, having joined Expedition 72, or the international crew of astronauts currently serving as the space station's official staff.
Williams even took over as commander of the entire space station on September 22.
NASA has said they have seamlessly integrated with the group and taken over daily tasks aboard the orbiting laboratory.
As part of Crew-9 and the formal expedition, Williams and Wilmore will handle typical crew duties, including conducting spacewalks outside the space station, maintaining the orbiting laboratory and conducting a tight schedule of scientific experiments.
And NASA previously confirmed that the Starliner astronauts are prepared to make such a change.
"A few years ago we made the decision - knowing this was a test flight - to ensure we had the proper resources, supplies and training for the crew in case they needed to be on the ISS for any reason . for an extended period of time," said Dana Weigel, NASA's manager of the International Space Station Program, during an Aug. 7 briefing.
"Butch and Suni are fully trained," Weigel added. "They are capable and current in EVA (spacewalks), in robotics, in all the things we need from them."
During recent updates on NASA's ISS activities, the space agency said Williams, Wilmore and their crewmates, NASA astronaut Nick Haag and Russian Aleksandr Gorbunov, will help move their Crew-9 capsule from its current port to the port that was opened when Crew-9 opened. 8 began its journey home from space. According to updates from NASA, they recently spent some time training for that task.
Williams and Wilmore have also had some downtime lately as they had to wait for days to support Crew-8's departure, which had been repeatedly postponed due to bad weather around Florida.
But the pair also occupied themselves with experiments and other daily tasks. For example, an Oct. 18 update from NASA states that during a half-day of work, Williams took a cognition test and "checked the connections on radio frequency identification hardware," while "Wilmore activated a fluorescent microscope to observe how particles of different sizes gel and coarsen." "
Williams and Wilmore had already spent a total of 500 days in space before embarking on this year's Starliner test flight. Williams even said she cried after leaving the space station after her last mission in 2012 because she wasn't sure she would ever return.
"This flight is a dream for her," said a NASA commentator during a June 5 livestream of the Starliner launch.
Long-term stay in space
It is not unusual for astronauts to unexpectedly extend their stay aboard the space station - by days, weeks or even months.
For example, NASA astronaut Frank Rubio would spend about six months aboard the International Space Station for his inaugural trip to low Earth orbit, which launches in September 2022. Instead, he logged 371 days in space after discovering a coolant leak. from its original ride - a Russian Soyuz capsule - while docked with the orbiting outpost.
Rubio's yearlong stay eventually set an American record for the number of continuous days in orbit.
Astronauts also routinely extend their stays on station for days or weeks at a time due to various factors, including bad weather on Earth or other schedule adjustments.
When asked at a press conference in September if he was having trouble adjusting to the prospect of waiting months longer to get home, Wilmore said, "I'm not going to worry about it." I mean, there's no benefit to it at all. So my transition was - maybe it wasn't immediate - but it was pretty close.
Williams said during the same news briefing that she missed her family and pets and was disappointed to miss some family events this fall and winter. But, she added, "This is my happy place. I love being here in the room. It's just fun. You know, every day you do something that's work, quote, unquote, you can do it upside down. You can do it sideways, so it adds a slightly different perspective.
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