Mark Edward Kelly (born February 21, 1964) is an American politician, former astronaut, and United States Navy captain who has served as the junior United States senator from Arizona since 2020. A member of the Democratic Party, he was elected in the special election held following the death of Senator John McCain, defeating incumbent Republican Martha McSally.
Kelly flew combat missions during the Gulf War as a naval aviator before being selected as a NASA Space Shuttle pilot in 1996. He flew his first space mission in 2001 as pilot of STS-108, piloted STS-121 in 2006, and commanded STS-124 in 2008 and STS-134 in 2011, the final mission of Space Shuttle Endeavour. His identical twin, Scott Kelly, is also a retired astronaut; they are the only siblings to have both traveled into orbit.