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 April 11, 2019 Get our newsletter! Get our newsletter! 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 You Might Also Like The Rebirth of “America by Air” January 31, 2018 Mustang and Raptor at Dusk September 21, 2015 Found September 20, 2008 The Dream is Aloft December 16, 2009 The first thing we do, let’s kill all the lawyers* May 1, 2012 Get the latest stories in your inbox every weekday. Email Powered by Salesforce Marketing Cloud (Privacy Notice / Terms & Conditions)