Scientists have sent hundreds of humans (and several animals) into space. Most of these missions have been relatively short: the longest space flight ever was about 15 months, 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 reported (wall of payments) some of the most complete data about the physical changes that occur when the body remains in space for about a year. The work concluded that, in fact, human physiology adapts to the new environment and, to a large extent, adapts to life on Earth once it returns.
The space is hard. On Earth, we are used to the comfortable pull of gravity and the mantle of radiological protection 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 it is not clear why), and the combination of radiation and the emotional stress of space travel even affects which parts of our genome are open for our cells to read.
For this document, a team of dozens of researchers from NASA and several institutions based in the USA. UU They used physiological data from Scott Kelly, an American astronaut who spent 340 days aboard the International Space Station from 2015 to 2016, and his brother, Mark, who remained on earth. Scott and Mark are identical twins, which means that they essentially have the same genetic material, which makes Mark a great control for the experiment.
Each brother collected blood, urine and feces samples while taking tests to evaluate things like his cognitive abilities and the shape of his eyes. The researchers spent the next three years badyzing any differences they might find. Indeed, Scott's body underwent a series of changes in space. Some were expected, as their eyes changing shape. But the scientists also observed that their immune system was also working harder, they performed better on cognitive tests, the composition of their gut microbiome changed, and some of their cells showed signs of reverse aging while they were in space. The telomeres, the part of our DNA that is shortened over time, actually grew in space. (Scientists suspect that this may have been the result of their cells working overtime to protect themselves from additional radiation damage.)
"When we go into space and experience microgravity and travel at speeds of 17,500 miles per hour, our bodies adapt and continue to function and, in general, work extremely well," said Steven Platts, deputy chief scientist of the Research Program. Human of NASA. CNN
Upon returning to Earth, Scott's body returned to the way it had been before, similar to Mark's; Their telomeres began to shrink within 48 hours of landing. The readjustment was difficult: his body ached under the force 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 worse (although this could be the result of a readjustment to a busy program of the earth).
As a sample of two, Scott and Mark Kelly can not provide definitive answers. Each astronaut is as unique as their genome, and therefore will have their own reaction to life in space. But knowing that the changes occur sets the stage for future investigations into what would happen to the body on longer missions, such as trips to Mars.
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