While space exploration carries many external risks, the biggest may be the effects of space life on the human body. These changes are often completely invisible and may include things like bone density loss, radiation, or chromosomal damage. It can be hard to accurately study the effects of space on a person. NASA has found a way around the potential complications through their so-called “Twins Study.”

The Twins Study project compares two NASA astronauts who happen to also be identical twins. Scott and Mark Kelly, already educated and skilled scientists, agreed to participate in the study. Scott was sent to the International Space Station while Mark remained on Earth. While the full findings are set to be released later this year, preliminary discoveries are already remarkable.

Scott’s telomers, a part of the body that protects human chromosomes from damage, experienced a dramatic growth while in space. This finding could be revolutionary, as longer telomers have often been linked to a significantly longer lifespan. In addition to protecting chromosomes, they allow cells throughout the body to replicate and regenerate numerous times before any decay happens to the genetic material. In theory, this could slow down the aging process and reverse many diseases. Learning how to make human cells more durable and resilient could lead to hundreds of medical breakthroughs. Interestingly, Scott’s telomers shrunk back down to normal size upon his return to earth.

Another incredible discovery was the volume of genetic mutations that occurred while Scott was in space. Researchers need more time to determine the impact these mutations have, and to learn whether or not scientists can expect these mutations to reverse. It is an important discovery, as studying the impact of long-term space travel on RNA and DNA can help set the stage for longer missions in the future.