Astronaut's DNA no longer identical to twin after year in space

Mark (left) and Scott (right) Kelly. NASA

Scott Kelly's DNA changed in space, but that doesn't mean what you think it means

Scott Kelly is no longer genetically the same as his brother Mark - after the Nasa astronaut spent a year in space.

Scientists compared the effects of space travel to Scott's twin, Mark, who remained on Earth and was treated as the control subject in the study. NASA's Twins Study is giving researchers insight into the effects of space travel on the body.

"Scott's DNA did not fundamentally change", a NASA statement. Preceding this, the space office distributed its initial round of preparatory outcomes at the 2017 Investigator's Workshop. Generally, the 2018 discoveries verified those from 2017, with a few additions.

It's believed the disrupted genes were caused by the stresses of space travel, such as oxygen deprivation. Those stresses contribute to the existence of hundreds of "space genes", explains Cornell University researcher Chris Mason. But the other 7% remained changed, even after Kelly returned to earth, signaling space travel can have longer-term changes on a person's body.

Other than his DNA, the study found most of the biological changes Scott Kelly experienced in space returned to normal after just hours or days on Earth, although some took months.

Mark (left) and Scott (right) Kelly. NASA
One Year In Space Changed Astronaut's DNA By 7 Percent, Compared To Twin On Earth

Yet as genes turn on and off, change in the function of cells may occur.

Kelly said he was surprised by that change in a recent interview with Marketplace.

- Scott's telomeres on the ends of his chromosomes in his white blood cells lengthened while in space. First, there was a significant increase in average length while he was in space, and then there was a decrease in length within about 48 hours of his landing on Earth that stabilized to almost preflight levels.

Scientists measured Kelly's metabolites, proteins, and cytokines to track physical changes caused by time in space. Ten groups of researchers, including Mason's team, are looking at a wide variety of information about the Kelly twins' health, including how gut bacteria, bones and the immune system might be affected by living off planet. Kelly's one-year on the ISS is a good precursor for a three-year mission NASA hopes to soon launch to Mars.

International Space Station (ISS) crew member Scott Kelly of the USA reacts after landing near the town of Dzhezkazgan, Kazakhstan, on March 2, 2016.

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