The effects of long-term space travel are still murky, but it’s something we’ll need to understand if humanity is ever going to take a trip to Mars and beyond. NASA is hoping to answer some of these questions with the aid of astronaut Scott Kelly. It just so happens Scott has an identical twin brother who could serve as a control. After a year in space, NASA says Scott Kelly’s genes behave differently, and the effect may be permanent.
Scott Kelly is a veteran of four space flights, and the last one was a doozy. For the so-called “year in space,” Kelly spent 340 consecutive days on the ISS, ending in March of 2016. His brother Mark Kelly is himself a former NASA astronaut of some repute, but he retired in 2011. He spent his fair share of time in space, but not for as long as his twin brother. This offered a unique opportunity for NASA to assess the effects of a year in space.
Some early media reports erroneously reported that Scott Kelly’s DNA had changed, making him no longer identical to his identical twin. However, that’s not an accurate description of what happened. It’s Kelly’s gene expression that is different, and the changes aren’t going away. That means his DNA has the same sequence it had before, but what his cells get from the DNA has changed.
What does that mean? Your DNA sequence consists of base pairs (signified by A, C, T, and G). Put a bunch of bases together, and they can form a gene. Cells read the DNA and build proteins based on the sequence that can be used internally or secreted into the body. However, not all genes are active, and there are often complex regulatory systems that tell cells which genes need to be turned into proteins.
NASA has found a 7 percent shift in Scott Kelly’s gene expression that has not gone away after two years back on Earth. To track the changes, NASA analyzed Scott Kelly’s cellular function before, during, and after the mission. These results were also compared with similar readings from Mark Kelly. Researchers theorize the changes are related to oxygen-deprivation stress, spaceflight-induced inflammation, and nutrient shifts.
A 7 percent shift in gene expression may not be significant, according to NASA. The greater concern may be the physiological stresses of long-term weightlessness. Kelly suffered from immune system hyperactivity, as well as bone and collagen formation abnormalities from his year in space.
This one-year mission could help NASA plan for a much longer trip to Mars and back. While some private space firms are looking to take people to the red planet very soon, it’s clear there’s still a great deal we don’t understand about the effects of space travel on humans.
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