- In full:
- Scott Joseph Kelly
- Born:
- February 21, 1964, Orange, New Jersey, U.S.
- Notable Family Members:
- brother Mark Kelly
- On the Web:
- CBS News - NASA astronaut Scott Kelly on life aboard the space station (Nov. 04, 2026)
Scott Kelly
News •
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Who is Scott Kelly?
Scott Kelly, born on February 21, 1964, is an American astronaut celebrated for his four spaceflights, including a 340-day mission, the longest by an American astronaut at the time. A U.S. Navy pilot, Kelly became an astronaut in 1996. His missions include STS-103 aboard the space shuttle Discovery and STS-118 on the Endeavour, contributing to the Hubble Space Telescope and the International Space Station (ISS).
Kelly's 340-day stay on the ISS with Russian cosmonaut Mikhail Korniyenko was part of a mission to study the effects of long-term spaceflight, including a unique twins study comparing Scott to his twin brother, Mark, also an astronaut. This research aimed to understand the impacts of space travel, relevant for future missions to Mars. Kelly retired from NASA in April 2016 and authored Endurance: A Year in Space, a Lifetime of Discovery.
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What did Scott Kelly do as an astronaut?
Scott Kelly is an American astronaut who has made four spaceflights. His longest mission lasted 340 days. On the STS-103 mission (December 19–27, 1999), he first flew into space as the pilot of the space shuttle Discovery to replace the gyroscopes and computer on the Hubble Space Telescope. He later flew to the International Space Station (ISS) as a mission commander. On the STS-118 mission (August 8–21, 2007), a truss was added to the ISS.
Kelly spent 340 days in space with Russian cosmonaut Mikhail Korniyenko as part of a special mission to the ISS. During this mission, he broke the American record for most cumulative time in space, with 520 days in orbit on his four flights. As part of the twins study, Kelly was compared with his twin brother, Mark, to understand the medical effects of long spaceflights. He and Korniyenko returned to Earth on March 2, 2016, and Kelly retired from NASA the following month.
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Which space missions did Scott Kelly participate in?
Scott Kelly, born on February 21, 1964, is an American astronaut who has undertaken four spaceflights. His missions include:
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STS-103: As pilot of the space shuttle Discovery (December 19–27, 1999), he replaced the gyroscopes and computer on the Hubble Space Telescope.
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STS-118: As mission commander aboard the space shuttle Endeavour (August 8–21, 2007), he added a truss to the International Space Station (ISS).
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Expedition 25/26: Kelly launched to the ISS on the Russian spacecraft Soyuz TMA-01M on October 8, 2010, and served as a flight engineer on Expedition 25 and became the commander of Expedition 26 (November 26, 2010–March 16, 2011).
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A special mission to the ISS (March 27, 2015–March 2, 2016) with Russian cosmonaut Mikhail Korniyenko, lasting 340 days. This was the longest spaceflight by an American astronaut at the time and included a twin study with his brother Mark to research the effects of long spaceflights.
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Why is Scott Kelly known for spending a long time in space?
Scott Kelly is an American astronaut known for his extended time in space. His most notable mission was a 340-day stay on the International Space Station (ISS) with Russian cosmonaut Mikhail Korniyenko. This mission, which launched on March 27, 2015, aimed to study the medical effects of long-duration spaceflight, relevant for future missions to Mars. Kelly also broke the American record for cumulative time in space, totaling 520 days across four flights. As part of the mission, scientists compared Scott to his twin brother, Mark, who remained on Earth, to understand the impact of space travel on the human body. He retired from NASA in April 2016 and published a memoir titled Endurance: A Year in Space, a Lifetime of Discovery in 2017.
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What was the purpose of the 'Year in Space' mission Scott Kelly joined?
The purpose of the "Year in Space" mission that Scott Kelly joined with Russian cosmonaut Mikhail Korniyenko was to study the medical effects of long spaceflights, similar to what astronauts would experience on a yearlong flight to Mars. Scientists compared Scott, who spent 340 days in space, with his twin brother Mark, who remained on Earth, to understand these effects. Kelly's 340-day flight was the longest spaceflight by an American astronaut at the time.
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How did Scott Kelly's mission help scientists learn about the effects of space on the human body?
Scott Kelly's mission significantly contributed to understanding the effects of space on the human body. As part of a special mission, he and Russian cosmonaut Mikhail Korniyenko spent 340 days on the International Space Station (ISS).
A key aspect of this mission was the twins study, which compared Scott with his twin brother, Mark, who remained on Earth. This unique study allowed scientists to investigate the medical impacts of prolonged spaceflight, relevant for future long-duration missions, such as a yearlong trip to Mars.
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Scott Kelly (born February 21, 1964, Orange, New Jersey, U.S.) is an American astronaut who made four spaceflights, the longest of which lasted 340 days. He is the twin brother of American astronaut and senator Mark Kelly.
Scott Kelly received a bachelor’s degree in electrical engineering from the State University of New York Maritime College at Throggs Neck, New York, in 1987. Scott and Mark became pilots in the U.S. Navy in 1987 and 1989, respectively. Both brothers graduated from the U.S. Navy Test Pilot School in Patuxent River, Maryland, in 1994. Scott received a master’s degree in aviation systems from the University of Tennessee, Knoxville, in 1996.
Scott and Mark Kelly began their astronaut training in August 1996. Scott first flew into space as the pilot of the space shuttle Discovery on the STS-103 mission (December 19–27, 1999), which replaced the gyroscopes and computer on the Hubble Space Telescope. He made a subsequent flight to the International Space Station (ISS) as a mission commander. On the STS-118 mission (August 8–21, 2007) of the space shuttle Endeavour, a truss was added to the ISS.
Scott launched to the ISS on the Russian spacecraft Soyuz TMA-01M on October 8, 2010. He served as a flight engineer on Expedition 25 and became the commander of Expedition 26, which lasted from November 26, 2010, to March 16, 2011. Mark was originally scheduled to arrive at the ISS in February 2011 as commander of the space shuttle Endeavour’s last mission, STS-134, and the Kelly twins would then have become the first siblings in space at the same time. However, delays in launching an earlier mission pushed STS-134’s launch to May 16, 2011.
On March 27, 2015, Scott returned to the ISS aboard Soyuz TMA-16M as part of a special mission in which he and Russian cosmonaut Mikhail Korniyenko spent 340 days in space, which was the longest spaceflight by an American astronaut. Scott broke the American record for most cumulative time in space, having spent 520 days in orbit on his four flights. (The record for longest spaceflight by an American astronaut was broken by Mark Vande Hei in 2022, and the American record for most cumulative time in space was broken in 2016 by Jeffrey Williams who spent 534 days in space.) A special part of the mission was the twins study, in which Scott was compared with the earthbound Mark to understand the medical effects of long spaceflight, such as astronauts would experience on a yearlong flight to Mars. Scott and Korniyenko returned to Earth on March 2, 2016. He retired from NASA the following month. Scott published the memoir Endurance: A Year in Space, a Lifetime of Discovery (2017).