Scott Kelly Biography

Astronaut (1964–)
Scott Kelly is a retired American astronaut who's served on four space flights in his career. His identical twin brother, Mark Kelly, is also a retired American astronaut, and together, they are the only siblings in history who've traveled to space.

Who Is Scott Kelly?

Born in 1964, Scott Kelly is a retired American astronaut, former military pilot, engineer and retired U.S. Navy Captain who's served on four space flights. For his first spaceflight, Kelly served as a pilot on the Space Shuttle Discovery in 1999, followed by Expedition 26, 45, and 46, serving as commander for the last three. In his final expedition, Kelly achieved his biggest feat in his NASA career by spending a year aboard the International Space Station (ISS) from March 2015 to March 2016. Shortly after returning to Earth, he announced his retirement on April 1, 2016. Kelly has an identical twin brother, Mark, who is also a retired astronaut and is married to Congresswoman Gabrielle Giffords. The brothers are the only siblings who've traveled to space.

Scott Kelly Photo

Scott Kelly


In July 2018 Kelly married his longtime girlfriend, Amiko Kauderer, in Houston, Texas.

Kauderer, who used to be a public relations officer at NASA, faithfully stood by Kelly while he spent his final year-long mission in space. 

Kelly was previously married to Leslie Yandell until 2009. They have two daughters, Samantha and Charlotte.

Early Life and Education

Scott Kelly was born Scott Joseph Kelly on February 21, 1964 in Orange, New Jersey to Irish parents Richard and Patricia Kelly.  

Although he was a self-admitted troublemaker in school who often fought with his twin brother, Scott finished high school in 1982. He then matriculated to the State University of New York (SUNY) Maritime College, receiving his four-year degree in electrical engineering in 1987 before finishing up his master's degree in aviation systems almost a decade later at the University of Tennessee, Knoxville.

Scott and Mark Kelly's DNA

One of the goals of Kelly's year-long spaceflight (the mission was actually 11 months) was to test how space's extreme environment affects the human body and how to better prepare future astronauts on future missions. 

When Kelly returned to Earth in March 2016, his genes were compared to that of his brother Mark. The initial findings showed that Kelly had a seven percent change in gene expression from Mark and that even six months later, those changes remained.

While Kelly's DNA did not change, "his body quieted some of his genes while amplifying others, so that his body produced more or less of certain key proteins in an attempt to adjust to the weird conditions of space and microgravity," explained Live Science. 

But that's not the entire story. According to Kelly, being in space for such a long time takes an immense physical toll on the body. Upon his return to Earth, Kelly told The Guardian he had to deal with "... stiffness, swelling of my legs, rashes where my skin hasn’t touched anything, nausea. In space you lose a significant amount of blood volume. You regain it when you get back very quickly, but what you don’t regain is the red blood cells you lost with it and that takes months to recover. That makes you feel fatigued. It’s a six- to eight-month recovery."

So is there any physical consolation to traveling to space? Perhaps. Technically, it shaved 13 milliseconds off Kelly's age. Considering he was already six minutes younger than his brother Mark, now he can say he's "six minutes and 13 milliseconds younger." 

Naval Career

In 1989 Kelly became a Naval Aviator and completed his training at the Naval Air Station Oceana, Virginia, before being deployed overseas. He later became a test pilot, eventually logging in over 8,000 flight hours and working up to the rank of U.S. Navy Captain before retiring from active duty in 2012.

NASA Spaceflight Career

STS-103 on the Space Shuttle 'Discovery' 

Kelly was a pilot on the Space Shuttle Discovery for his first spaceflight in December 1999. The mission, which spanned eight days and three spacewalks, installed updates and upgrades to the Hubble Space Telescope. 

STS-118 on the Space Shuttle 'Endeavor'

In August 2007, Kelly was chosen as the commander for the STS-118 Endeavor, whose mission was to install a new system that allowed electricity to power docked shuttles to extend their stay at the International Space Station (ISS). Three crew members conducted four spacewalks to complete the mission, which lasted a little over 12 days.

ISS Expedition 25 and 26

On October 7, 2010, Kelly flew with two Russian cosmonauts, Commander Aleksandr Kaleri and flight engineer Oleg Skripochka, aboard an enhanced Soyuz TMA-01M rocket to the ISS. Serving as a flight engineer, Kelly and the Russian cosmonauts arrived two days later to the ISS, which started the second half of Expedition 25 and expanded the crew to six members, the three others being Commander Douglas H. Wheelock and flight engineers Fyodor Yurchikhin and Shannon Walker. The mission involved bringing 2.5 tons of supplies to the space station.

Once half of the crew returned to Earth on November 25, 2010, Kelly began his command of Expedition 26 and during his two-month stay, he and the rest of the crew members were visited by multiple international space vehicles that brought supplies and technical services. Among them was the STS-133 on the Space Shuttle Discovery, but because it experienced launch problems, it caused a delay in the subsequent shuttle mission STS-134, which was commanded by Kelly's twin brother, Mark. 

Had there been no delay, Expedition 26 would've coincided with STS-134, and the twin brothers would've had an overlap of eight days in space together, making them the first siblings and twins to be in space simultaneously. Instead, however, Mark's mission would take off later that May.

When Kelly's mission ended and he landed back on Earth on March 16, 2011, he rushed to aid Mark, whose wife, Congressman Gabrielle Giffords, had been shot earlier that January in Tucson, Arizona. 

One Year in Space

In 2012 Kelly, along with Russian cosmonaut Mikahail Kornienko, were chosen by NASA for a year-long space mission (technically, 11 months) aboard the ISS. Kelly and Kornienko were already familiar each other, having flown together on earlier missions. 

On March 27, 2015 the two veteran space explorers took off to the ISS in a Russian Soyuz spacecraft from a spaceport in Kazakstan. Their year-long mission focused on collecting data on how the human body is affected by the harsh climate of space, which in turn could better prepare astronauts on future missions — even to Mars. Researching genetic variations, NASA used Kelly as an experimental subject, while his Earth-bound twin, Mark, functioned as the control group. 

While in space, Kelly set a space record. According to his website: "In October 2015, he set the record for the total accumulated number of days spent in space... by an American astronaut" which clocked in at 520 days. (His record was later broken in 2016 and 2017 by astronauts Jeff Williams and Peggy Whitson, respectively).

During his 11-month mission, Kelly orbited the Earth 5,440 times and performed three spacewalks.

So was Kelly anxious when he conducted his first spacewalk?

"Not especially. I’ve had a knack for compartmentalizing since my days in the navy," Kelly told The Guardian. "There are so many little tasks to take care of on a spacewalk – eight hours is barely enough time to complete everything we’re assigned. So I just kept focused on what was in front of me: my gloves, the pieces of the station in front of me. I barely even looked at the Earth looming just outside my field of vision."

Kelly returned to Earth on March 1, 2016 and retired from NASA exactly a month later.


In October 2017, Kelly published a memoir, Endurance: A Year in Space, a Lifetime of Discovery, which chronicles his career with NASA and his year-long mission in space.

Fact Check

We strive for accuracy and fairness. If you see something that doesn't look right, contact us!