NASA astronaut Sunita 'Suni' Williams retired from the agency on December 27, 2025, following a 27-year career that included three space missions. Williams accumulated 608 days in space and performed nine spacewalks, holding several human spaceflight records, including the most spacewalk time by a woman. Her final mission was an extended test flight aboard Boeing's Starliner spacecraft.
Retirement Announcement and Acknowledgment
Williams' retirement was announced by NASA Administrator Jared Isaacman, who acknowledged her contributions to human spaceflight and commercial missions. Vanessa Wyche, director of NASA's Johnson Space Center, also highlighted Williams' leadership and dedication, particularly during the Boeing Starliner mission.
Career Milestones and Records
Williams, who joined NASA in 1998, completed three flights to the International Space Station (ISS). Her total time in space, 608 days, ranks as the second-longest cumulative time for a NASA astronaut. She holds the record for the most spacewalk time by a woman, with nine spacewalks totaling 62 hours and 6 minutes, placing her fourth on the all-time cumulative spacewalk duration list.
During her career, Williams set several other records:
- She is credited with the sixth-longest single spaceflight by an American, at 286 days, a duration she shared with NASA astronaut Butch Wilmore during the NASA Boeing Starliner and SpaceX Crew-9 missions.
- She was the first individual to complete a marathon in space in 2007.
- In 2012, she became the first person to complete a triathlon in space, utilizing specialized equipment.
Space Missions
Williams's spaceflight career includes three principal missions:
- First Mission (2006-2007): She launched in December 2006 aboard Space Shuttle Discovery (STS-116) and returned with Space Shuttle Atlantis (STS-117). During this period, she served as a flight engineer for Expeditions 14 and 15 on the ISS and conducted four spacewalks.
- Second Mission (2012): In 2012, Williams launched from the Baikonur Cosmodrome for a 127-day mission as part of Expedition 32 and 33. She commanded the space station during Expedition 33 and performed three spacewalks for tasks such as repairing a radiator leak and replacing a power component.
- Third Mission (2024-2025): Her most recent mission began in June 2024, launching with Butch Wilmore on Boeing's Starliner spacecraft for NASA’s Boeing Crew Flight Test. They joined Expeditions 71 and 72, with Williams again commanding the space station for Expedition 72. She completed two spacewalks during this mission before returning to Earth in March 2025 as part of the SpaceX Crew-9 mission.
Boeing Starliner Crew Flight Test Context
The Starliner mission, initially projected for approximately one week, extended to over nine months. This extended duration was attributed to technical issues encountered with the Starliner vehicle during its transit and while docked at the ISS, including thruster outages and gas leaks. NASA subsequently decided to return the Starliner spacecraft to Earth uncrewed for safety considerations.
Following the mission, Williams commented on the Starliner's capabilities, noting that while some aspects required adjustments, it was a capable spacecraft with distinct features. Both astronauts indicated they enjoyed their time in orbit despite the unexpected extension.
NASA has stated that the next Starliner mission is planned to be uncrewed, serving as an additional test flight in response to the issues observed during Williams and Wilmore's flight. Williams' retirement follows that of fellow Starliner test pilot Butch Wilmore.
Other Contributions and Background
Beyond her spaceflights, Williams held various leadership and operational roles within NASA. In 2002, she participated as a crew member in the NEEMO (NASA Extreme Environments Mission Operations) program. She later served as deputy chief of NASA’s Astronaut Office and as director of Operations in Star City, Russia. More recently, she contributed to establishing a helicopter training platform designed to prepare astronauts for future lunar landings.
A native of Needham, Massachusetts, Williams holds a bachelor’s degree in physical science from the United States Naval Academy and a master’s degree in engineering management from Florida Institute of Technology. She is a retired U.S. Navy captain with extensive experience as a helicopter and fixed-wing pilot, accumulating over 4,000 flight hours across 40 different aircraft types.
In her farewell statement, Williams expressed appreciation for her time at NASA and her colleagues, stating that space was her preferred environment. She voiced hope that the work accomplished would facilitate future exploration to the Moon and Mars.