Living in space for almost a year has had interesting effects on American astronaut Scott Kelly.
Scientists have discovered signs of increased activity in its immune system, the body's natural defenses against diseases. Life in space has also changed the activity of some of Kelly's genes compared to those of her identical twins brother, who stayed on Earth.
Scientists presented their findings at a conference earlier this month. But they admit that they do not know yet whether the changes are good or bad.
The results are part of a larger, special twin study conducted by NASA, the US space agency. The study raises new questions for doctors as agency officials plan to send people to the planet Mars.
The tests of Kelly and her genetically identical brother gave scientists an unprecedented chance to study the details of human biology. They are able to examine how an astronaut's genes light up and go out in space differently from those of the Earth.
An unexpected change announced at the recent meeting of the American Association for the Advancement of Science: Kelly's Immune System was hyperactivated.
The geneticist Christopher Mason helped lead the study. Mason works at Weill Cornell Medicine, Cornell University School of Medicine in New York. He told The Associated Press that doctors are now looking for this unusual disease in other astronauts.
"It's like the body reacts to that extraterrestrial a bit like a mysterious organism within you, "said Mason.
The effects of space exploration on health
Since the beginning of space exploration, NASA has studied its effects on the body of astronauts. One of the effects is bone loss, which results from being in a low-gravity environment over a prolonged period. As a result, astronauts must now perform physical exercises during long space flights.
Usually, astronauts are in space about six months at a time. Kelly, who lived on the International Space Station, spent 340 days in space and set an American record.
"I never felt completely normal in space," writes Kelly in an email to The Associated Press. He noted congestion and headaches, attention problems and stomach problems.
But this study was a glimpse of the molecular level, with former astronaut Mark Kelly, Scott's twin brother, on the ground for comparison purposes.
A number of genes related to the immune system have become hyperactive, said Charles Mason. This is not a change DNA, carrying genetic information, but in what is called "gene expression". This term is used to describe how genes deactivate and increase or decrease their protein production.
Mason also noted an increase in blood flow from another marker that prepares the immune system. However, at the same time, Kelly's blood had fewer cells of another type of early defense against viruses.
It is not surprising that gene activity changes in space – it changes in response to all kinds of conditions.
The good news is that almost everything returned to normal shortly after Kelly's return to Earth in March 2016. However, these immune-related genes, "seemed to have this memory or need to be almost at the top alert"Even six months later, Mason added.
Craig Kundrot directs scientific research on life in space and NASA. He seemed satisfied with the results.
"There are no major new warning signs. We are seeing changes that we do not necessarily have to anticipate"But we do not know if these changes are important," said Kundrot.
NASA already knew that it was possible for the Russians to spend a lot of time outside the Earth, while four Russians had been living in space for over a year, Kundrot specified. He added, "We are also aiming more than we can. We want our astronauts to do more than survive. "
In the end, the twin study gives NASA a list of things to look for in the future Assignments to see if other astronauts react in the same way. Astronauts in future flights will be able to do some of these tests in space instead of freezing blood and other materials for scientists returning home, Mason said.
A human mission According to Kundrot, Mars, which NASA hopes will be available in the 2030s, would take 30 months, including time spent on the surface.
Radiation is a major concern. The trip would be exhibit astronauts at radiation levels above NASA's safety limits. It's "just a little over," he said.
On the Earth and even on the space station, the Earth's magnetic field protects astronauts from high levels of radiation. There would be no such protections on the way to Mars and back, but special structures could help them on the planet, Kundrot said.
I am Anna Matteo.
And I'm Pete Musto.
Lauran Neergaard and Seth Borenstein reported this story to the Associated Press. Pete Musto adapted it for VOA Learning English. George Grow was the publisher.
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Words in this story
identical double – not. either a member of a pair of two babies who are produced from a single egg and who are exactly alike
hyperactivated – adj. made more active than usual or desirable
extraterrestrial – adj. unfamiliar or like other things you've known
congestion – not. a condition in which part of the body is blocked by a liquid, such as blood or mucus
DNA (Deoxyribonucleic acid) – not. a substance that carries genetic information in the cells of plants and animals
alert – not. the state of being ready for something for which you have been warned, such as an attack
to anticipate – v. think of something that will or may happen in the future
exhibit – v. bring someone to experience something or to be influenced or affected by something
mission – not. A flight made by a plane or a spaceship to perform a specific task