What happens to your body after nearly a year in space? A lot. Most things return to normal once back on Earth – but not all.
This is the extremely detailed summary of NASA's "Twins Study," whose results were published Friday in the journal Science.
The study followed the physiological and cognitive changes of astronaut Scott Kelly when he spent 340 days in space and compared them to his twin brother, Mark Kelly – also a retired astronaut – back home. .
NASA collected and analyzed 317 stool, blood and urine samples from Mark and Scott during the year. He also tested elements such as the memory of twins, as well as their cardiac and ocular function. (Scott has also received an influenza vaccine aboard the International Space Station – the first vaccine ever administered in space – and his body has responded appropriately – even aboard the ISS, its immune system was much more active than her twin, according to the study.)
Although 559 people went to space, only eight of them spent more than 300 consecutive days in orbit. This has led to a dearth of information about what happens to the human body in microgravity over time – important information to possess if NASA is seriously considering sending humans to Mars at over the next decades. A trip to the red planet takes about 300 days.
Scott came back to earth about three years ago and found most of his time, NASA discovered, including his immune system, his cognition and his microbiome. But 7% of its gene expression has not yet regained its pre-flight status, potentially due to DNA damage due to increased exposure to radiation.
And in another genetic surprise, the ends of Scott's chromosomes – a protective sequence called telomeres – actually elongate in space. These generally shorten with age, and their length is correlated with age-related health risks, such as heart disease and cancer.
"We have certainly imagined, in our study, that unique types of stress and extreme environmental exposures, such as space radiation and microgravity, would help accelerate telomere loss," said Susan Bailey, Researcher. at Colorado State University and a co-author of the research, said at a press conference earlier this week. "We were surprised."
But Bailey warned against hope that NASA came across a cure for aging.
"I do not think that [the elongation] can really be considered as the fountain of youth and that people can expect to live longer because they are in space, "she said.
NASA discovered that Scott's telomeres were getting shorter "a few days after landing" on Earth. It is unclear why, even if the explanation can be decidedly terrestrial: Scott's diet in space contained more folate (vitamin B9), which probably played a role.
Overall, however, NASA researchers have returned encouraged by the results.
"The bottom line is," Scott told Space.com, "of all these studies – and, of course, it's an experience with just one data point … would be that there was nothing we had saw that would prevent us from going to Mars. "