NASA astronaut Scott Kelly’s one-year stay on the International Space Station will be a one-of-a-kind science experiment studying the effects of long-duration spaceflight, made possible by history’s only set of two-of-a-kind spacefliers.
The mere fact that Kelly will be in space for roughly a year (actually, 342 days), starting Friday, is not a record-setter. Four Russian cosmonauts spent longer stints on the Mir space station. But this marks the first time that an American astronaut has done it, and the first time that scientists will compare a space traveler’s health with that of an identical twin on Earth over the course of a year.
Scott Kelly’s twin, retired astronaut Mark Kelly, has volunteered to be the earthly guinea pig.
“I believe in science,” said Mark Kelly, who is a space and aviation analyst for NBC News and MSNBC. “I’m very grateful for the opportunities that the U.S. government has given me, NASA in particular, so I’m glad to do it.”