Astronaut Scott Kelly experienced many changes during his 340-day stay at the International Space Station (ISS), ranging from changes in genes and intestinal microbes to the thickening of his carotid artery, NASA researchers said the astronaut involved and his identical twin, Mark Kelly.
The body of the astronaut is almost back to normal after returning to Earth in March 2016. However, Kelly said that it had taken her at least six months to feel like before.
"The return was far worse than the fit to ride there, especially for the year flight," Kelly told reporters. "I felt like I had the flu after the first few days, I was tired for a very long time."
While Mark Kelly stayed on Earth during the experiment, he is also a NASA-trained astronaut who has completed several space shuttle missions between 2001 and 2011.
Mark Kelly, pictured in his NASA uniform in 2011, is also an experienced astronaut.
Surprise for researchers
The study, published in the journal Science On Friday, watched Kelly twins aged 55 before, during and after Scott Kelly's trip to assess the effects of a prolonged space flight on the human body. Some of the results, such as weight loss and bone loss in the space twin, were in line with scientists' expectations. At the same time, the results showed that Scott Kelly was suffering from damage to DNA and changes in the way his genes were activated and deactivated.
What is most confusing to the researchers, they also indicated that Scott Kelly's telomeres, the protective ends of the chromosomes that were progressively shortening as we get older, actually took longer when he was in space.
"We were surprised," Susan Bailey, telemetry expert at Colorado State University, told the press, but noted that the change did not mean that Kelly had become biologically younger during her trip.
After returning to Earth, Kelly's telomeres generally returned to their pre-flight average, but he had more short telomeres than before. However, a small percentage of its genes related to the immune system and DNA repair remained impaired, indicating possible permanent damage.
Road map for Mars
The flight also resulted in changes in the structure of Kelly's eye and a thickening of her retina, which affects about 40% of astronauts. Another discovery of the study is that a flu vaccine works as well in space as it does on the Earth, according to the study.
The data collected during the study would help scientists plan long lunar missions and three-year trips to Mars, where space radiation is far more important than on board the ISS.
Scott and Mark Kelly are both retired and Mark goes to the US Senate as a Democratic Party candidate in Arizona.
dj / ng (Reuters, dpa, AP)
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