In the first look, one might say that Scott Kelly and Mark Kelly are identical twins, as they really are, but with two different sets of DNA.
In 2015, while Scott spent a year in space, his sibling Mark remained on Earth, giving NASA a one of a kind chance to perceive how spaceflight changes the human body and brain.
After spending a year in space when Scott came back, NASA uncovered some fascinating results - about 7 per cent of Scott Kelly's DNA changed in space.
What is the study about?
When NASA astronaut Scott Kelly stood up last March after spending a year in space, he was two inches taller. The engineer and veteran of four space flights is part of a long haul NASA study that aims to figure out how being in space changes our bodies and brains.
Scott Kelly is specially assigned to give NASA key insight into these changes because he is both an astronaut and a twin. For its research, NASA is comparing Scott Kelly's DNA with the identical DNA of his twin brother, Mark Kelly.
Mark remained on Earth for Scott's 340-day stretch on board the International Space Station, giving NASA the rare opportunity to compare how being in space acted upon his genes.
Although each Kelly brother was born with the similar set of DNA, life has exposed each set of genes to a range of divergent experiences - space being one of them. Those experiences affect the way the Kellys' genes are expressed.
What were the results?
- Scott's newly discovered height ended up being just a brief aftereffect of his spine being physically stretched in a gravity-free environment, and not a change to his genes
- But it's just one of the many alterations the researchers have documented up until this point
- Deep within Scott's DNA, they are finding a scope of changes that are not present in his brother Mark
- While some were temporary and seemed to occur only while he was in space, others were durable
Here's what the principal investigator on the NASA twins study, Christopher Mason
"When he went up into space it was like fireworks of gene expression," said Christopher Mason, a principal investigator on the NASA twins study. "But the changes that seem to have stuck around include changes in immune system function and retinal function related to his eye health."
In numerous regards, Kelly's genes show the signs of a body responding to what it perceives as a threat, he included.
"Oftentimes when the body encounters something foreign, an immune response is activated. The body thinks there's a reason to defend itself. We know there are aspects of being in space that are not a pleasant experience and this is the molecular manifestation of the body responding to that stress."
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