When Scott Kelly came back to Earth, the astronaut wasn’t quite the same.
Research by NASA and Weill Cornell Medicine suggests long-term space flight can cause gene expression changes. The DNA of Kelly and his identical twin are being used to prove it.
NASA astronauts Mark and Scott Kelly were the subjects in the study; Mark stayed on Earth as a control subject while Scott took off in 2015 for a one-year mission on the International Space Station.
Christopher Mason, a geneticist at Weill Cornell Medicine, and a team of NASA scientists found a variety of behavioral, genetic and physiological changes in the twins including weight loss, lengthening of chromosomes, retina and carotid artery thickening, gut microbe shifts and more. It’s still unclear if the DNA changes are overwhelmingly good or bad, but researchers hope the study can help prevent or treat health issues as astronauts endure long missions.
“Gene expression changed dramatically. In the last six months of the mission, there were six times more changes in gene expression than in the first half of the mission,” Mason said.
After Scott returned to Earth, a number of the changes he experienced reversed while others, like DNA changes and cognitive deficiencies, remained intact.
“It is likely that these two astronauts have been studied at greater depth than any other person in history. They give us a really in-depth view of cellular, molecular and physiological changes that can help us learn what is in the range of what a human can endure,” Mason said.