A new Twins Study by Nasa has revealed that spending time in space causes subtle physiological and chromosomal changes in the human body.

The Twins Study conducted by Nasa’s Human Research Program from 2015-2016 investigated retired astronauts Scott Kelly and his identical twin brother Mark.

It provides the first integrated biomolecular view into how the human body responds to the spaceflight environment.

It also serves as a genomic stepping stone to gain better knowledge on how to maintain crew health during human expeditions to the Moon and Mars.

Nasa Headquarters chief health and medical officer JD Polk said: “The Twins Study has been an important step toward understanding epigenetics and gene expression in human spaceflight.

“Thanks to the twin brothers and a cadre of investigators who worked tirelessly together, the valuable data gathered from the Twins Study has helped inform the need for personalised medicine and its role in keeping astronauts healthy during deep space exploration, as Nasa goes forward to the Moon and journeys onward to Mars.”

“The Twins Study has been an important step toward understanding epigenetics and gene expression in human spaceflight.”

As part of the study, Mark provided a baseline for observation on Earth, and Scott provided a comparable test case during the 340 days spent by him in space onboard the International Space Station for Expeditions 43, 44, 45, and 46.

The Nasa Twins Study released key results related to gene expression changes, immune system response, and telomere dynamics.

It was also found that chromosomes broke and rearranged themselves in chromosomal inversions.

Scott said that the telomeres in his white blood cells were unexpectedly longer in space then shorter after his return to Earth. Average telomere length returned to normal after six months. His immune system responded appropriately in space.

In contrast, the telomeres of Mark remained stable throughout the entire period.

The Nasa Twins Study incorporated ten investigations and helped establish a framework of collaborative research that serves as a model for future biomedical research.