Caption:
NASA Expedition 45/46 Commander, Astronaut Scott Kelly along with his brother, former Astronaut Mark Kelly at the Johnson Space Center, Houston Texas, 2015. Mark and Scott Kelly are identical twins, and will be studied for changes in their health, comparing a body in space to a body on earth. Scott Joseph Kelly (born February 21, 1964) is an American astronaut, engineer and a retired U.S. Navy Captain. A veteran of three previous missions, Kelly was selected along with Mikhail Korniyenko in November 2012 for a special year-long mission to the International Space Station. Kelly commanded the International Space Station (ISS) on Expedition 26. Kelly's identical twin brother, Mark Kelly, is a former astronaut. The Kelly brothers are the only siblings to have traveled in space. Mark Edward Kelly (born February 21, 1964) is a retired American astronaut, engineer and U.S. Navy Captain. He is the husband of former Congresswoman Gabrielle Giffords, an author, a political activist, and an aerospace executive and consultant.