NASA Twin Study: Year in Space Changed Scott Kelly All the Way to His DNA

10_26_Scott Kelly and Mark Kelly
Astronauts Scott Kelly and Mark Kelly speak onstage at Day One of LocationWorld 2016 at Conrad New York, in New York City, on November 2, 2016. Being in space takes an immense physical toll on the body. But it may also change astronauts’ genes, scientists discovered. Brain

Scientists have long known that being in space takes an immense physical toll on the body. But it may also change astronauts' genes, according to research on NASA's Scott Kelly and his identical twin brother, Mark Kelly.

In the space agency's Twins Study—which investigates the effects of space travel on human health—researchers found that being in space encourages methylation, which is the biological process of switching genes on and off. It's when a methyl group, which is one carbon and three hydrogen atoms, is added to another molecule. It's understood that the process plays a key role in gene expression, but there's still many unknowns. Currently, many experts are exploring the link between methylation abnormalities and various cancers.

"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," Chris Mason, lead researcher of the Twins Study, said in a NASA video.

The process of thousands of genes changing "happens as soon as an astronaut gets into space, and some of the activity persists temporarily upon return to Earth," Mason, an associate professor at Weill Cornell Medicine, added.

Although the study is yet to be completed, the preliminary results shed light on understanding the microlevel changes of the body in space.

"This really sets the bedrock for our understanding of molecular risks for space travel, as well as ways to potentially protect and even fix them," Mason said.

Current findings were possible thanks to Scott Kelly's 340-day mission aboard the International Space Station. Upon returning to Earth from his record-setting journey, study authors gathered biological samples. His twin brother, Mark Kelly—who remained on Earth during the same period time—also had samples collected from him, in order for researchers to compare their DNA profiles.

The detailed findings of the study—scheduled to be published in 2018—provide "a stepping stone toward long-duration space exploration such as journeys to Mars," according to the NASA.

Another notable change the body endures in space is muscle mass meltdown. The drastic shift "is equivalent of a 20-year-old turning into a 60-year-old over a period of three months," Jeremy Curtis, of the United Kingdom Space Agency, told the BBC. In order to combat this, astronauts must follow strict exercise regimes in space that involve 2.5 hours of movement.