Biography of Scott Kelly, Astronaut Who Spent a Year in Space

Astronauts Scott Kelly And Mikhail Kornienko Give A Press Confence At UNESCO in Paris
US astronaut Scott Kelly at a press conference with Russian cosmonaut Mikhail Kornienko at the UNESCO on December 18, 2014 in Paris, France. Kelly and Kornienko embarked on a year-long mission to the International Space Station (ISS) in March 2015. Chesnot / Getty Images

On March 2017, Scott Kelly, astronaut, blasted off to the International Space Station (ISS) on his fourth flight to orbit. He spent a year aboard, racking up a record total of 520 days in space over his career. It was both a scientific and personal achievement, and his time on orbit continues to help scientists understand the effects of microgravity on the human body.

Fast Facts: Scott Kelly

  • Born: February 21, 1964 in Orange, New Jersey
  • Parents: John and Patricia Kelly
  • Spouses: Leslie Yandell (m. 1992-2009) and Amiko Kauderer (July 2018-present)
  • Children: Charlotte and Samantha (with Yandell)
  • Education: United States Merchant Marine Academy, University of Tennessee (MS)
  • Published Works: "Endurance: A Year in Space," "My Journey to the Stars," and "Infinite Wonder: An Astronaut's Photographs From a Year in Space"
  • Accomplishments: Spent a year in space as part of the Twins Study of long-term effects of microgravity on humans

Early Life

Astronaut Scott Joseph Kelly and his identical twin brother Mark (who also served as an astronaut) were born on February 21, 1964, to Patricia and Richard Kelly. Their father was a police officer in Orange, New Jersey. The twins went to school at nearby Mountain High, graduating in 1982. During high school, Scott trained and worked as an emergency medical technician. From there, Scott went to college at the University of Maryland in Baltimore.

In his memoir Endurance: My Year in Space, a Lifetime of Discovery, Kelly wrote that his early college years were difficult, and he lacked direction in his studies. By his own admission, his high school grades were bad and his SAT test scores weren't impressive. He wasn't sure what to do with himself. Then, he picked up a copy of Tom Wolfe's The Right Stuff and the words he read impressed him deeply. "I felt like I had found my calling," he wrote about that time in his life. "I wanted to be a naval aviator...The Right Stuff had given me the outline of a life plan."

To pursue that plan, Scott transferred to the New York Maritime Academy, where his twin brother Mark was already attending college. He graduated in 1987 with a degree in electrical engineering and went on to earn a masters' degree in Aviation Systems from the University of Tennessee. As a commissioned officer in the U.S. Navy, Kelly attended flight school in Pensacola, Florida, and later flew jets at various duty stations. In 1993, he attended Naval Test Pilot School at Patuxent in Virginia, and over the course of his career amassed more than 8,000 hours of flying time in dozens of different aircraft in both land and carrier landings.

Mark and Scot Kelly, twin astronauts.
Astronauts Scott Kelly (right) and Mark Kelly (left) in an interview about their work with the Twins Study and as astronauts. NASA 

NASA and Dreams of Flight for Astronaut Kelly

Scott Kelly and his brother Mark both applied to become astronauts and were accepted in 1996. Scott was trained in caution and warning systems for the ISS. His first flight was aboard space shuttle Discovery on STS 103, a Hubble Space Telescope servicing mission. His next assignment took him to Star City, Russia, where he served as Director of Operations there for joint Russian-American flights. He also served as backup for crew members on several ISS missions. Due to the Columbia accident in 2002 (for which he flew search and recovery operations), flights were postponed until NASA could investigate the causes of the tragedy.

Scott next worked as the Astronaut Office Space Station Branch Chief in Houston before doing a stint on the NEEMO 4 mission. That underwater training laboratory in Florida was developed to study the similarities between living in space and underwater for long periods of time in enclosed quarters under simulated space conditions.

Kelly's next two flights were to the International Space Station for STS-118, and Expeditions 25 and 26, where he worked for several months. He participated in installing instruments for the station, as well as a variety of science experiments.

Scott Kelly in a selfie in the cupola of the ISS.
Astronaut Scott Kelly in the cupola section of the international Space Station. NASA

Scott Kelly and the Astronaut Twins Experiment

The final mission for Scott Kelly was part of the famous "Twins Study." For that, he spent nearly a year in microgravity while his brother Mark, who is now a retired astronaut, stayed on Earth. Scientists devised the experiment to study the effects of prolonged microgravity on Scott, and compare changes in the two over the course of the mission and beyond. The study also provided valuable information about how astronauts living and working in space on long-term voyages to the Moon and Mars can be affected. The mission began for him on March 27, 2015, when he blasted off from Earth with Russian cosmonaut Mikhail Korniyenko. Kelly was on for two missions and was commander for the second one. He returned to Earth on March 11, 2016.

In addition to the Twins Study, Mark worked with Russian colleagues aboard the station and was commander for the mission during part of his stay. He traveled to and from the station aboard a Russian rocket and capsule. Among other activities, Kelly performed an extravehicular activity with fellow astronaut Timothy Kopra to repair a mobile transporter aboard the station. He also did an EVA with Kjell Lindgren to service several parts of the station, including the Canadarm 2 and installation of docking equipment for future missions by SpaceX and NASA crew vehicles.

Scott Kelly personal quarters on ISS.
Scott Kelly's personal living quarters aboard the International Space Station were quite small and include a sleeping and personal work area.  NASA

The ongoing research into changes in both men has uncovered some significant effects of space flight. During his time in on orbit, Scott grew two inches in height due to weaker gravitational pull on his skeleton. Upon return to Earth, his skeletal structure returned to nearly the same as it was before the mission. Genetically, the men remain the same, but scientists noted some ways that his body's gene expression had changed. This is not the same as his actual genes changing, but has more to do with how they prepare the body to respond to changes in the environment.

In addition, Scott participated in research to help doctors understand why astronaut eyesight can change drastically over time in space. He, like many other astronauts, noted a distinct change in mental viewpoint and also how personal relationships are affected by lengthy stays in space.

Kelly noted that one unique aspect of the mission was that time on the station flowed at a slightly different rate than it did for his brother on Earth. It made him slightly younger than Mark and medical scientists are still assessing the effects of his trip on his body. He wrote that his part as a scientific lab rat never ends. "I will continue to be a test subject for the rest of my life," he wrote. "I will continue to participate in the Twins Study as Mark and I age...for me, it's worth it to have contributed to advancing human knowledge, even if it's only a step on a much longer journey."

Personal Life

Scott Kelly married his first wife, Leslie Yandell in 1992 and they had two daughters, Samantha and Charlotte. The couple divorced in 2009. Kelly married his second wife, Amiko Kauderer, in 2018.

Scott Kelly retired from NASA in 2016 and has worked with the United Nations Office for Outer Space Affairs since that time. The memoirs of his time in space were published in 2017, and he spends time giving public talks about space and space travel. "I've been traveling the country and the world talking about my experiences in space," he wrote. "It's gratifying to see how curious people are about my mission, how much children instinctively feel the excitement and wonder of spaceflight, and how many people think, as I do, that Mars is the next step."

Honors and Awards

Scott Kelly received many medals and much recognition for his work, among them the Legion of Merit, the Navy and Marine Corps Commendation Medal, the NASA Distinguished Service Medal, and the Medal for Merit in Space Exploration from the Russian Federation. He is a member of the Association of Space Explorers and was one of Time Magazine's Influential 100 in 2015.


  • Kelly, Scott, and Margaret Lazarus Dean. Endurance: My Year in Space, a Lifetime of Discovery. Vintage Books, a Division of Penguin Random House, LLC, 2018.
  • Mars, Kelli. “Twins Study.” NASA, NASA, 14 Apr. 2015,
  • Mars, Kelli. “NASA Twins Study Confirms Changes to Mark Kelly's Genes.” NASA, NASA, 31 Jan. 2018,
  • Northon, Karen. “NASA Astronaut Scott Kelly Safely Back on Earth after One-Year Mission.” NASA, NASA, 2 Mar. 2016,
  • “Scott Kelly.” Scott Kelly,
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Petersen, Carolyn Collins. "Biography of Scott Kelly, Astronaut Who Spent a Year in Space." ThoughtCo, Aug. 28, 2020, Petersen, Carolyn Collins. (2020, August 28). Biography of Scott Kelly, Astronaut Who Spent a Year in Space. Retrieved from Petersen, Carolyn Collins. "Biography of Scott Kelly, Astronaut Who Spent a Year in Space." ThoughtCo. (accessed March 20, 2023).