NASA astronauts Butch Wilmore and Sunita Williams went on an eight-day test flight on Boeing’s Starliner. Still, they ended up remaining aboard the International Space Station (ISS) for 286 days after their propulsion system failed on their spacecraft.
Released on June 5, 2024, they aimed to fly Boeing’s first Starliner crew. Technical complications, though, made NASA hold them in the ISS until they could devise a safe return. On March 19, 2025, both the astronauts ultimately splashed down safely off the Florida coast in the SpaceX Crew-9 Dragon spacecraft.
Their extended stay makes them part of the astronauts who have stayed the longest in space on one mission.
Top 10 Longest Space Missions by Astronauts
Valeri Polyakov – 437 Days: Set the record for the longest solo spaceflight on Mir (1994-1995), circling the Earth more than 7,000 times.
Sergei Avdeyev – 379 Days: Remained on Mir Space Station (1998-1999) for 379 days following an unplanned mission extension.
Frank Rubio – 371 Days: Establish the U.S. spaceflight record on ISS (2022-2023) following a coolant leak that prolonged his stay.
Vladimir Titov & Musa Manarov – 365 Days: First to orbit the sun once in space on board Mir (1987-1988).
Mark Vande Hei – 355 Days: Lived for 355 days on ISS (2021-2022), helping with research on muscle wasting and space agriculture.
Scott Kelly & Mikhail Kornienko – 340 Days: Completed NASA’s “One-Year Mission” on ISS (2015-2016), supporting Mars exploration research.
Christina Koch – 328 Days: Remained on ISS for 328 days (2019-2020), conducting six spacewalks, including the first two all-female ones.
Peggy Whitson – 289 Days: Set the record for the longest single woman spaceflight (2016-2017), totaling 675 days in space.
Sunita Williams & Butch Wilmore – 286 Days: Remained on ISS longer than scheduled (2024-2025) due to Boeing Starliner propulsion problems.
Andrew Morgan – 272 Days: Took 272 days aboard ISS, logging seven spacewalks and undertaking a dark matter study.
Sunita Williams broke the record for the total cumulative spacewalking time of a female, standing at 62 hours and six minutes, exceeding that of Peggy Whitson, 60 hours and 21 minutes.
