Sunita (Suni) Williams, the American astronaut of Indian origin, announced her retirement from NASA after 27 years of service, NASA said on January 20. Her retirement, effective from December 27, 2025, followed completing three missions aboard the International Space Station and setting multiple human spaceflight records during her career.
Williams ranks second among NASA astronauts for cumulative time spent in space and holds the record for the most spacewalk time by a woman. She also became the first person to run a marathon in space.
Williams logged 608 days in orbit across three missions. She completed nine spacewalks, totalling 62 hours and six minutes, which places her fourth on the all-time cumulative spacewalk duration list. She is also tied for sixth place on NASA’s list of longest single spaceflights by an American astronaut, after logging 286 days on a single mission.
“Anyone who knows me knows that space is my absolute favourite place to be,” Williams said in the statement. “It’s been an incredible honour to have served in the Astronaut Office and have had the opportunity to fly in space three times. I am super excited for NASA and its partner agencies as we take these next steps, and I can’t wait to watch the agency make history.”
Williams first travelled to space in December 2006 aboard the space shuttle ‘Discovery’ as part of the STS-116 mission. She returned in June 2007 on space shuttle Atlantis with the STS-117 crew. During this mission, she served as a flight engineer on Expeditions 14 and 15 and completed four spacewalks, a record at the time.
NASA Administrator Jared Isaacman said Williams played a key role in advancing human spaceflight. “Suni Williams has been a trailblazer in human spaceflight, shaping the future of exploration through her leadership aboard the space station and paving the way for commercial missions to low Earth orbit,” he said.
In 2012, Williams launched aboard a Russian Soyuz spacecraft from the Baikonur Cosmodrome in Kazakhstan for a 127-day mission aboard the International Space Station. She served as a member of Expeditions 32 and 33 and later took command of the station during Expedition 33. During this mission, she carried out three spacewalks to repair a station radiator leak and replace a power distribution component.
Her most recent mission began in June 2024, when Williams and astronaut Butch Wilmore launched aboard Boeing’s Starliner spacecraft for NASA’s Crew Flight Test mission. The mission marked the first crewed test flight of the Starliner. Williams and Wilmore later joined Expeditions 71 and 72, during which she again served as space station commander.
Williams completed two spacewalks during the mission and returned to Earth after 9 months in space in March 2025 aboard SpaceX’s Crew-9 mission.
Vanessa Wyche, director of NASA’s Johnson Space Center in Houston, said Williams’ career set a benchmark for future astronauts. “From her indelible contributions and achievements to the space station, to her groundbreaking test flight role during the Boeing Starliner mission, her exceptional dedication to the mission will inspire future generations of explorers,” she said.
Beyond her missions, Williams held several leadership and operational roles at NASA.
She served as a crew member on the NASA Extreme Environments Mission Operations programme in 2002, spending nine days living and working in an underwater habitat. After her first spaceflight, she became deputy chief of NASA’s Astronaut Office.
Following her second mission, Williams served as director of operations in Star City, Russia. In her later years at NASA, she helped establish a helicopter training platform designed to prepare astronauts for future Moon landings.
Scott Tingle, chief of the Astronaut Office at NASA Johnson, said Williams was widely respected within the astronaut corps. “She’s inspired so many people, including myself and other astronauts in the corps,” he said.
Williams is also a retired US Navy captain and a trained helicopter and fixed-wing pilot with more than 4,000 flight hours across 40 aircraft.
Reflecting on her career, Williams said her work was shaped by the people and missions she supported. “The International Space Station, the people, the engineering, and the science are truly awe-inspiring and have made the next steps of exploration to the Moon and Mars possible,” she said.
