Space travel caused lasting changes to 7% of genes of astronaut Scott Kelly, according to a NASA study which compared his DNA to that of his identical twin brother, who remained on the earth.
NASA’s Twins Study brought ten research teams together to accomplish one goal: find out what happens to the human body after spending one year in space.
NASA has a grasp on what happens to the body after the standard-duration six-month missions aboard the International Space Station (ISS), but Scott Kelly’s one-year mission is seen as a stepping stone to a three-year mission to Mars.
In 2017, ten teams had presented their preliminary findings at NASA’s Human Research Programme investigators’ workshop.
Reports included data on what happened to Scott Kelly, physiologically and psychologically, while he was in space, and compared the data to Mark Kelly, as a control subject on the earth. At this year’s workshop, findings from 2017 were corroborated, with some additions.
Researchers also presented what happened to Scott Kelly after he returned to the earth. By measuring large numbers of metabolites, cytokines, and proteins, researchers learned that spaceflight is associated with oxygen deprivation stress, increased inflammation, and dramatic nutrient shifts that affect gene expression.
After returning to the earth, Scott Kelly started the process of re-adapting to gravity. Most of the biological changes he experienced in space quickly returned to nearly his preflight status. Some changes returned to baseline within hours or days of landing, while a few persisted after six months.
Scott’s telomeres — end caps of chromosomes that shorten as one ages — actually became significantly longer in space.
While this finding was presented in 2017, the team verified this unexpected change with multiple assays and genomics testing.
A new finding is that the majority of those telomeres shortened within two days of Scott’s return to the earth. Researchers now know that 93% of Scott’s genes returned to normal after landing.
However, the remaining 7% points to possible longer term changes in genes related to his immune system, DNA repair, bone formation networks, hypoxia and hypercapnia.