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From his eyes to his immune system, the body of astronaut Scott Kelly has sometimes reacted in a strange way after nearly a year in orbit, at least compared to his twin identical to that related to the Earth – but recently published research shows nothing that can cancel even longer trips to space, such as on Mars. .
The good news: Kelly has largely bounced back after returning home, said scientists who published the final results of NASA's "twin study," an unprecedented opportunity to track the biological consequences of spaceflight in double genetics.
It marks "the dawn of human genomics in space," said Dr. Andrew Feinberg of Johns Hopkins University. He led one of 10 teams of researchers who examined the health of twins at the molecular level before, during, and after Kelly's 340-day stay at the International Space Station.
More importantly, the study "represents more than a step forward for humanity" by highlighting the potential risks of long-duration spaceflight that need to be studied by more astronauts, said Markus Lobrich of the university. German Darmstadt and Penny Jeggo of the University of Sussex, who said: not involved in the work.
The results were published in the Friday edition of the journal Science, on some notable anniversaries in space – when Soviet cosmonaut Yuri Gagarin became the first person in space in 1961 and the first launch of the space shuttle in 1981.
Main conclusions
NASA already knew some of the negative consequences of space travel, such as bone loss, which requires physical exercise. This time, scientists funded by NASA have searched for a range of physiological and genomic changes that Scott Kelly has experienced in space, comparing them to his double ground DNA, former astronaut Mark Kelly. Some results were reported in February.
Perhaps the most bizarre discovery is that of telomeres, the protective ends of chromosomes. As we get older, these tips gradually shorten and are thought to be related to age-related diseases, including some cancers.
But in space, Scott Kelly's telomeres have become longer. "We were surprised," said Susan Bailey, a telomere expert at Colorado State University. She can not explain it well that does not mean that Kelly has become younger. Back on Earth, his telomeres have generally returned to the mean before the flight although he has had more short telomeres than before.
Then, Kelly's DNA has not been mutated in space, but the activity of many of its genes – their mode of activation and deactivation – has changed , especially during the last part of the trip, which ended in March 2016.
The immune system genes in particular have been affected, placing it "almost in a state of alert to try to understand this new environment," said co-author of the study, Christopher Mason, geneticist of Weill Cornell Medicine in New York.
Again, most genes returned to normal in their home country, but some of the immune-related genes were hyperactive six months later.
Other findings:
– Some changes in the structure of Kelly's eye and the thickening of his retina suggest that, like about 40% of astronauts, he exhibited symptoms of "neuro-ocular syndrome associated with spaceflight". This may be due to fluid movement in the absence of gravity.
– He experienced chromosomal instability that may reflect exposure to radiation in the space.
– A given flu shot in space worked, as well as another on Earth.
– Kelly was tested in space, but slowed down after her return, perhaps as more things were competing for her attention.
Ultra long distance test
The researchers needed several months of blood, urine and stool samples, as well as cognitive and physical tests and ultrasounds.
This involved being creative: some blood samples required such a quick analysis that Kelly calculated the sampling time so that blood could circulate in Russian Soyuz capsules carrying other astronauts to Earth.
It would not be an option for a three-year trip to Mars. One of the technological advances in the study: a portable DNA sequencing equipment that will allow astronauts to perform some of their own genomic analyzes in future missions, said Mason de Weill Cornell.
And after?
The study of a pair of twins can not prove the risks of spaceflight, the researchers warned. And longer missions, to the Moon or Mars, will result in greater exposure to stress and radiation.
Bailey, of the state of Colorado, plans to study 10 more astronauts on missions lasting one year, using twin results as a roadmap.
"We need to get out of low Earth orbit and ask astronauts to spend more time actually evaluating some of these health effects," she said.
Image credit:
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