(CNN) – NASA has learned that after astronaut Scott Kelly returned from space, not all of his genes returned to normal.
The NASA Twins Study looked at what happened to Scott Kelly before, during and after he spent one year aboard the International Space Station through an extensive comparison with his identical twin, Mark, who remained on Earth.
According to researchers, the preliminary results show 7 percent of Scott Kelly’s genes changed because of his space travel, so the twins are no longer genetically the same.
NASA says the changes suggest longer-term changes in the genes related to the immune system, DNA repair, bone formation, oxygen deficiency and excessive carbon dioxide in the bloodstream.
Some of the gene mutations, found only after spaceflight, are thought to be caused by the physical stresses of space travel.
What? My DNA changed by 7%! Who knew? I just learned about it in this article. This could be good news! I no longer have to call @ShuttleCDRKelly my identical twin brother anymore. https://t.co/6idMFtu7l5
— Scott Kelly (@StationCDRKelly) March 10, 2018
The Twins Study is helping NASA gain insight into what happens to the human body in space beyond the usual six months astronauts spend on the ISS.
Scott Kelly’s one-year mission is said to be a stepping stone to a three-year mission to Mars.
But NASA says more research into how the human body adjusts to weightlessness, isolation, radiation and the stress of long-duration spaceflight is needed before any Mars missions can begin.
More details are expected to be released later this year.
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