When NASA decided to put a man in space for an year to study what outer space does to humans, they picked astronaut Scott Kelly. He could have been NASA's perfect candidate because he came with an added advantage—an identical twin brother, retired astronaut Mark Kelly. And then began the Twins Study, an intriguing health experiment that connects outer space conditions with human physiology. After spending 340 days on board the International Space Station, Scott returned to earth in March 2016. During the mission, NASA simultaneously monitored the twin brothers, one floating in space and the other on earth. Recently, the space agency released some interesting preliminary findings on how his stay in space changed Scott Kelly's body and genetic make-up compared to that of his twin's.
The Twins Study
Previous outer space missions have identified many physiological side effects of microgravity on the bodies of astronauts—wasted muscles, low bone density, diminishing eyesight, altered blood count levels, and a higher risk of cancer. Now that space agencies around the world are working towards taking a man to Mars, the mission would require the crew to be in outer space for at least three years. In fact, the one-way travel alone would take nearly eight months. To counter the impact of microgravity on astronauts, scientists need to develop a plan. And this is where NASA expects the results of Twins Study to come handy. The study involves assessing the impact of different environments on individuals with same genetics. In this case, the Kelly brothers.
Researchers took biological samples from each brother before, during, and after Scott's space mission. They compared nearly identical genomes—with one of the twins in microgravity environment facing space stress factors and the other on earth engaged in normal life—to map the effect of spaceflight at a molecular level. The study employed a new technique known as Omics—a detailed branch of technology that deals with massive observations at the biomolecular level.
What did they observe?
1. Scott's telomeres got longer, then shrunk back: Telomeres are DNA sequences at the end of chromosomes that protect them form deterioration. Often referred to as 'ticking clocks of the cell', these get shorter as we age. It was observed that Scott's telomeres got longer that his brother's while in space, and they shrunk back to normal length once he was back on Earth. Though this is the opposite of what was expected, scientist's are still figuring out its meaning. It could be a result of more exercise and reduced caloric intake while he was in space, according to NASA.
2. Drop in bone formation, cognitive intelligence: The team found a decrease in Scott's bone formation in the second half of the mission, and also observed a drop in cognitive ability. But these observations aren't strong enough to make a conclusion about cognitive abilities of astronauts on longer space missions.
3. Different gut bacteria: The twins hosted different gut bacteria—microrganisms in the gastrointestinal tract that help in digestion. This could, again be due to changed diets.
4. Unique genetic mutations: Whole-genome sequencing of Mark and Scott revealed that both twins have hundreds of unique genetic mutations. RNA sequencing showed more than 200,000 RNA molecules that were expressed differently between the twins. Researchers will look closer to see if a 'space gene' could have been activated while Scott was in space, said NASA.