Scott Kelly

Scott Kelly is an American NASA astronaut and retired United States Navy captain who spent nearly 340 consecutive days aboard the International Space Station during a 2015 to 2016 mission, at the time the longest single spaceflight by an American. He is the identical twin brother of fellow astronaut Mark Kelly, and NASA used the pair in a Twins Study comparing the biological effects of long-duration spaceflight, since Scott spent the year in orbit while Mark remained on Earth as a genetically matched control subject.