Space have altered the DNA of one-half of an identical pair of twin astronauts. Scott Kelly and Mark Kelly no longer share the same genetic makeup following Scott's 340-day stint aboard the International Space Station (ISS).
After six months, Scott reverted to only 93% of his pre-flight genetics. "Some of the most exciting things that we've seen from looking at gene expression in space is that we really see an explosion, like fireworks taking off, as soon as the human body gets into space," principal investigator of The Twins Study, Dr. Chris Mason, said.
After a medical assessment, scientists discovered that about seven percent of Scott's genes are now different from his brother's following the study. The genes which permanently changed involved DNA repair, bone formation and how the cells use oxygen.
"With this study, we've seen thousands and thousands of genes change how they are turned on and turned off. This happens as soon as an astronaut gets into space, and some of the activity persists temporarily upon return to Earth,” Mason explained.
The physical demands of living in a micro-gravity environment have been documented, but before the study conducted with the Kelly, twins was done scientists believe any changes to the body was reversible.
However, Scott returned to Earth in March 2016, and his body has yet to return to its original state. According to Newsweek, Scott’s body experienced oxygen deprivation stress, increased inflammation and nutrient shifts when he returned to Earth, and genes related to immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia never reverted to their pre-flight conditions.
"This study represents one of the most comprehensive views of human biology. It really sets the bedrock for understanding molecular risks for space travel as well as ways to potentially protect and fix those genetic changes," the study head said.
Born Scott and Mark have served as US Navy captains, flew on the Endeavour and Discovery space shuttles as well as aboard the ISS.