When astronauts Butch Wilmore and Sunita Williams embarked on Boeing’s Starliner capsule on June 5, 2024, they expected to be away from home for just over a week.
Instead, they spent around 9 months in orbit on the International Space Station. But after over 286 days, their extended stay in space is finally coming to a close, as the two astronauts make their way back to Earth on a SpaceX capsule that’s set to splash down off the coast of Florida on Tuesday. 
Wilmore, 62, and Williams, 59, are both veteran NASA astronauts and retired U.S. Navy test pilots. Williams became an astronaut in 1998 and Wilmore in 2000. The two were the first crew aboard what was meant to be a quick test flight for the Starliner. But the vessel was plagued with problems that almost prevented it from making it to the ISS, including a helium leak and thruster malfunctions. NASA ordered the Boeing capsule to return unmanned in September, while Wilmore and Williams were left aboard the space station awaiting a safe flight home.
At the end of January, President Donald Trump and SpaceX CEO Elon Musk blamed the Biden Administration for delaying the astronauts’ return—which former space station commander Andreas Morgensen called “a lie.” Musk claimed in posts on X that SpaceX offered to bring Williams and Wilmore home months earlier, but that it was denied for “political reasons.” (Former NASA officials said no offer was made to the space agency, and former NASA administrator Bill Nelson said the decision to wait until February for the stranded astronauts to return home rested on safety procedures).
In August, NASA decided to bring them back on a SpaceX capsule. The Dragon-9 vessel launched in September but remained docked at the ISS while waiting for a relief crew. That relief mission saw hold-ups: the scheduled flight was meant to launch in February but was delayed due to battery work on the SpaceX capsule. A hydraulics issue delayed another launch attempt last Wednesday with a new SpaceX capsule. On Friday, NASA and SpaceX successfully launched the Crew-10 mission to orbit with four astronauts aboard a SpaceX capsule that arrived at the ISS on Saturday to relieve Wilmore and Williams.
Such a long time spent in space can take a physical and mental toll, but Wilmore and Williams’ expedition isn’t the longest spaceflight. Five previous American astronauts—including the U.S. record-holder Frank Rubio as well as Peggy Whitson, who has spent the most cumulative days in space for an American astronaut—have spent more days in space on a single mission. And Russian cosmonauts hold the worldwide records for both consecutive and cumulative days in space.
World’s longest single stay in space: Valery Polyakov
Russian cosmonaut Valery Polyakov set the world record for the longest single spaceflight in history in 1995, spending 437 days, 17 hours, and 38 minutes in space and orbiting the Earth 7,075 times, according to the New Mexico Museum of Space History.
Having studied astronautical medicine at Moscow’s Institute of Medical and Biological Problems, Polyakov became an asset to the study of the effects of space on the human body.
At the age of 46, he launched to the Mir space station aboard Soyuz TM-6 on Aug. 29, 1988—16 years after becoming a Soviet cosmonaut in 1972. He was accompanied by fellow Soviet cosmonaut Vladimir Lyakhov and Abdul Ahad Momand, Afghanistan’s first astronaut. While the rest of his crew returned to Earth just a week later, Polyakov stayed on to monitor the health of cosmonauts Vladimir Titov and Musa Manarov, who endured the first year-long spaceflight. After Titov and Manarov returned to Earth in December 1988, Polyakov remained on Mir for another four months to await two new crewmembers.
Polyakov ultimately returned to Earth in April 1989, marking more than 240 days in space, according to the Moscow Times.
For his record-setting second mission, Polyakov was aboard Mir for 14 months, beginning on Jan. 8, 1994. Across 25 experiments and investigations, he studied the physical and cognitive functions of rotating crews from Russia, Kazakhstan, Germany, and the U.S. On March 22, 1995, Polyakov boarded the Soyuz TM-20 spacecraft, alongside Aleksandr Viktorenko and Yelena Kondakova, to return to Earth.
Upon his return, Polyakov refused the standard practice of being carried out of the spacecraft, instead insisting on walking himself with some assistance, according to author of The Story of Manned Space Stations, Philip Baker. His extended expedition allowed scientists to study how human bodies might be affected by long-distance voyages, such as to Mars. Tests found that he was neither physically nor cognitively impaired.
Polyakov died on Sept. 19, 2022, at the age of 80.
U.S. longest single stay in space: Frank Rubio
With 371 consecutive days spent in space, Salvadoran American astronaut Frank Rubio broke the record for the longest spaceflight by an American and the longest time spent aboard the International Space Station. He landed in Kazakhstan on the morning of Sept. 27, 2023, more than a year after leaving Earth.
Rubio was launched into space on Sept. 21, 2022, aboard the Russian spacecraft Soyuz MS-22—his first mission since becoming a NASA astronaut in 2019. The mission was initially expected to take six months, but the spacecraft suffered a coolant leak, forcing the trip to be extended. Russia’s space agency sent an uncrewed Soyuz MS-23 spacecraft to bring home Rubio and his crewmates, Russian cosmonauts Sergey Prokopyev and Dmitri Petelin.
Rubio’s time in space spanned 5,963 orbits of the Earth and more than 157 million miles. He beat the previous record for an American astronaut of 355 days set by Mark Vande Hei.
World’s longest total time in space: Oleg Kononenko
Another Russian cosmonaut holds the record for total time spent in space. Oleg Kononenko became the first person to log a total of 1000 days in space last June—an equivalent of 33 months.
Kononenko broke the previous record of 878 cumulative days in orbit set by fellow cosmonaut Gennady Padalka. His time in space spanned 16 years, five ISS expeditions, and 16,000 orbits around the Earth.
U.S. longest total time in space: Peggy Whitson
Whitson, 65, has broken several records over the course of her astronautical career. In 2017, she broke the U.S. record for the longest cumulative time spent in space of 534 days set by NASA astronaut Jeff Williams, and has held the record since, accumulating 675 total days. She also holds the record for the longest cumulative and consecutive times spent in space for a woman of any nationality, and became the first female commander of the ISS in 2008—and the first woman to command it a second time in 2016. She has flown on three long-duration missions with NASA, and one flight with Axiom Space.
Williams moves just behind Whitson notching a total of 608 cumulative days in space after her third spaceflight. (Wilmore, meanwhile, will have spent a total of 404 cumulative days in space across his three spaceflights.)
