Permanent mutation in the astronaut DNA! New discovery! The NASA astronauts stayed in space for 340 days and the DNA was permanently mutated.

Did NASA’s Twin Study Results Just Change Spaceflight Forever? NASA astronaut Scott Kelly spent 340 days at the International Space Station. Scientists wondered if his physical condition had changed. So he found the same twin brother Mark Kelly to compare, and found that Scott's "immune system and DNA repair function" mutation, from the genetic point of view, is a permanent damage that cannot be recovered.