When astronaut Scott Kelly started the process of readapting to Earth's gravity after returning from a year on the International Space Station — the longest ever for a NASA astronaut — most of the biological changes he experienced in space quickly returned to normal. Yet some changes persisted after six months: most notably that 7 percent of his DNA remained alien "space DNA," NASA reported last week.
Not only that, Scott Kelly's telomeres — the caps at the end of DNA strands that protect the chromosomes and deteriorate with age — lengthened, and he came back 2 in. taller, although both his telomeres and his height reverted to normal proportions back on Earth.
NASA's findings are part of the Twins Study, conducted by NASA's Human Research Program, to observe how the body responds to extended periods in outer space, in light of NASA's goal of a human-crewed mission to Mars by the 2030s, a round-trip expected to take about two and a half years.
Reports included data on what happened to Scott Kelly, physiologically and psychologically, while he was in space, and compared the data to his identical twin brother, Mark Kelly, as a control subject on Earth. What researchers observed were changes in Scott's gene expression, which is how your body reacts to your environment.
There is no doubt that space does mysterious things to a body. Astronauts commonly report vision problems; others get post-flight kidney stones, most likely a result of the high level of carbon dioxide in the ISS air supply, which produces high concentrations of calcium oxalate in the bloodstream and thus stones to form in the kidneys.
Recent studies in the past two years examining astronauts bodies before, during and after spaceflight reveal cellular changes in their spinal cords, eyes and brains that, in many cases, resemble deterioration due to diseases on Earth, particularly those related to aging. Many of these, including arthritis, osteoporosis, glaucoma and vertigo, currently have no cures.
In order to succeed in a long-term trip to Mars and beyond, astronauts will need solutions to these issues. Scientists studying how to overcome them are translating what they find to generate solutions for similar medical conditions here on Earth.