Scientists have sent hundreds of humans (and several animals) in space. Most of these missions were relatively short – the longest flight in space was about 15 months. It was performed by Russian cosmonaut Valery Polyakov more than two decades ago. As a result, scientists do not have much data on the physiological changes that occur in the body after long periods of time in space.
On April 11, a team of scientists (Paywall) released some of the most comprehensive data on the physical changes that occur when the body stays in space for about a year. The research concludes that human physiology is adapting to the new environment and is largely reshaping life on Earth once it returns.
The space is hard. On Earth, we are used to the gravity and radiological protection blanket of the atmosphere. Without gravity, our bones and muscles, which no longer have to support the body, weaken. The eyes also seem to change shape (although we do not know why), and the combination of radiation and emotional stress related to space travel affects even the parts of our genome open to reading by our cells.
For this article, a team of dozens of researchers from NASA and several US institutions used the physiological data of Scott Kelly, a US astronaut who spent 340 days aboard the International Space Station from 2015 to 2016, as well as his brother , Mark on Earth. Scott and Mark are identical twins, which means that they have essentially the same genetic material, which makes it an excellent control for the experiment.
Each brother took blood, urine and stool samples, while passing tests to assess such things as their cognitive abilities and the shape of their eyes. Researchers have spent the next three years analyzing potential differences. Indeed, Scott's body has undergone many changes in space. Some were expected, as his eyes changing shape. But scientists also observed that his immune system also worked harder, he had better results on cognitive tests, the composition of his gut microbiome had changed, and some of his cells showed signs of reverse aging in the space. Telomeres, the part of our DNA that is shrinking over time, have developed in space. (Scientists suspect that his cells would have had to work longer to protect themselves from the additional damage caused by radiation.)
"When we go into space, we live in microgravity and we travel at a speed of about 17,000 km / h, our body adapts and continues to work, and works globally extremely well. well, "said Steven Platts, deputy chief scientist of NASA's human research program. CNN.
When he returned to Earth, Scott's body became as before, in the manner of Mark; his telomeres began to contract within 48 hours of landing. The readjustment was difficult – his body was suffering again under the effect of gravity, for example.
However, some changes remained permanent six months later: a fraction of Scott's genes were still read differently by his cells and his cognitive abilities were less good (although this may be the result of a readjustment to a busy terrestrial calendar) .
Scott and Mark Kelly can not provide definitive answers to the sample. Each astronaut is as unique as his genome and will therefore have his own reaction to life in space. But knowing that changes are happening paves the way for future research on what would happen to the body during longer missions, such as trips to Mars.
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