By Rajni Pandey | March 18, 2025
The most experienced NASA astronaut, Whitson completed three ISS missions and added 9 days with Axiom-2 in 2023, securing the record for the most cumulative days in space by an American.
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With 322 days from past missions, Williams’ 2024 Starliner mission was unexpectedly extended due to technical issues, adding about 284 days, making her one of NASA’s most seasoned space travelers.
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A veteran of four spaceflights, Williams spent a cumulative 534 days in space, with his longest mission being 172 days aboard the ISS during Expedition 47 in 2016.
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Vande Hei held the U.S. record for the longest single spaceflight (355 days in 2021-22) until Frank Rubio surpassed him. His total space time from two missions stands at 523 days.
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Kelly’s “One Year Mission” aboard the ISS (340 days in 2015-16) provided critical data on long-duration spaceflight, making him one of the most studied astronauts in space history.
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With 178 days from earlier missions, Wilmore launched aboard Starliner in June 2024 for a short mission, which was extended due to technical issues, adding around 284 days to his total.
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A physician-astronaut, Barratt logged 447 days in space across two ISS missions, contributing to extensive medical research on long-duration human spaceflight.
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Kimbrough, a veteran of three spaceflights, accumulated 388 days in orbit, including multiple spacewalks during his ISS missions to upgrade and maintain station systems.
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With three ISS missions (2004, 2008-09, 2011), Fincke is among NASA’s longest-serving astronauts, contributing 382 days in space over his career.
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