Mankind’s quest to become an interplanetary species is a bold one that will have a lot of challenges in the coming decades, not simply in terms of technology or creating a colony on an alien planet, but also because space has drastic effects on the human body. As we reported recently, scientists found that 7 percent of DNA belonging to NASA astronaut Scott Kelly changed in the time he was aboard the International Space Station, a remarkable finding with big implications on future space travel.

It shows that space has huge effects on the human body, and we do not quite understand what risks we face in that regard. A trip to Mars would last months, and then there’s also the question of how the Martian environment would affect us as well. Suffice to say, there are a lot of unknowns in the race to colonize the Red Planet.

Researchers examined Kelly’s psychology and physiology, as well as genetics, and found that while most of the readings went back to normal after he returned to Earth, about 7 percent of genes did not. Scott Kelly gave NASA a unique opportunity to conduct this study, as he has a twin brother, Mark, who remained on Earth that scientists could compare his DNA to.

“Scott’s telomeres (endcaps of chromosomes that shorten as one ages) actually became significantly longer in space,” the NASA statement reads. “While this finding was presented in 2017, the team verified this unexpected change with multiple assays and genomics testing. Additionally, a new finding is that the majority of those telomeres shortened within two days of Scott’s return to Earth.

“Another interesting finding concerned what some call the “space gene”, which was alluded to in 2017. Researchers now know that 93% of Scott’s genes returned to normal after landing. However, the remaining 7% point to possible longer term changes in genes related to his immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia.”