AIR & SPACE MAGAZINE

NASA’s Study of Astronaut Twins Creates a Portrait of What a Year in Space Does to the Human Body

Wide-ranging research compares astronaut Scott Kelly to his earthbound twin brother, Mark

Scott and Mark Kelly
Identical twin astronauts, Scott and Mark Kelly, are subjects of NASA’s Twins Study. Scott (right) spent a year in space while Mark (left) stayed on Earth as a control subject. NASA

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