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After A Year Of Space Travel, This Astronaut Returned To Earth With DNA That No Longer Matched His Twin Brother’s

Bill Ingalls/NASA via Getty Images

NASA astronaut Scott Kelly returned to Earth after a year of space travel and new studies reveal that his DNA is now different from that of his identical twin brother, Mark Kelly.

The results of the NASA study show how the physical and mental impact of living in space for a year can significantly change the human body.

“Researchers learned that spaceflight is associated with oxygen deprivation stress, increased inflammation, and dramatic nutrient shifts that affect gene expression,” NASA’s website explains.

The telomeres, or caps, of Scott’s chromosomes (which aid the human aging process) lengthened as a result of space travel. Ninety-three percent of Scott’s DNA has gone back to normal after landing, but seven percent still appears different from his identical twin brother’s. But not all changes were internal.

The findings also include observations of external changes on Scott’s body caused by space travel. According to Live Science, after the astronaut’s return to Earth, he “was two inches taller than he’d been when he left. His body mass had decreased [and] his gut bacteria were completely different.”

Scott also experienced a decrease in speed and accuracy, but that could have been a result of feeling gravity again and the busy schedule that met him as soon as he stepped off his flight.

This study tells us a lot about the impact long-term space travel has on the human body, and how the health and safety of astronauts can be studied and protected as space-travel technology continues to improve with time.