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Space oddities: the twins helping us reach for the stars

Space oddities: the twins helping us reach for the stars

The overall takeaway, she said, is that the immune system is revved up under the stressors of space flight.

The idea for the NASA Twins Study came from Scott Kelly himself, during preparations for his 340-day-long mission in space with Russian cosmonaut Mikhail Kornienko, said co-lead investigator Dr. Andrew Feinberg, director of the Center for Epigenetics at Johns Hopkins University.

These findings ran counter to what Bailey thought might occur, and are confirmed in "The NASA Twins Study: A multi-dimensional analysis of a year-long human spaceflight", published in Science April 12.

The Kelly brothers were part of a year-long study to assess how spaceflight affects the human body.

Results of from a comparison of genetic changes in an astronaut who spent almost a year in space and an identical twin brother who remained in Earth have demonstrated that chromosomes changed in space returned to normal on Earth, with limited permanent changes in gene expression, NASA announced in a press release on Thursday.

While Mark Kelly stayed Earth-bound during the experiment, he is also a qualified NASA astronaut who flew several space shuttle missions between 2001 and 2011.

Supply vessels transported urine, blood and stool samples from Scott back to Earth. Mark underwent identical tests.

"When we looked at individual telomere length and distributions, he did have many more short telomeres after flight than he did before", Bailey said.

There was also a spike in circulating markers of inflammation, especially so called c-reactive proteins (CRP), which are predictive of cardiovascular problems.

The flu shot Scott Kelly received in space worked just as it would have on Earth, which suggests the immune system functions normally during spaceflight.

His immune system took a hit too. Kelly retired from NASA soon after his return.

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"A lot of the genes that got activated were part of his DNA damage response, or his radiation response". "They included things that affect DNA maintenance and fix, as well ramping up the immune system when it's needed".

Going forward, a critical issue NASA must tease out is what changes in astronauts' bodies are due to shifts in gene activity and expression, versus the novelty of living in such a foreign environment. Not all of the changes disappeared-or at least not quickly-after Scott's return.

The study is exceptionally detailed ("They measured as many things as they possibly could", said Richard Gronostajski, a geneticist at the State University of NY at Buffalo), but when it's all distilled down, the message about spending a year in space - exposed to microgravity and mildly higher levels of radiation - is relatively clear. "At a point nine months after return, we still saw elevated inversions".

Even so, the question of spaceflight-associated aging and the accompanying risk of developing age-related diseases like dementia, cardiovascular disease and cancer - during or after a mission - is an important one, and one that we aimed to address directly with our study of telomere length. "Radiation exposure will certainly be a very big concern", Bailey said.

Having shorter telomeres puts a person at higher risk for accelerated aging, said Bailey. Long-term effects of research, such as the ongoing telomeres investigation, will continue to be studied. "We couldn't have been more surprised by what we saw". "We're seeking correlations that can explain how this is happening".

"And I got people coming to my house for tubes of blood", Mark replied.

What's more, scientists may see clear biological changes in space - like the lengthening of Scott Kelly's telomeres - but it's uncertain what that means, if anything. In space, the diet and the environment are more or less consistent, producing an unusually stable microbiome. Six months after his return to Earth, the majority of his levels were back to normal.

But in an interview with The Washington Post, Scott Kelly, now 55, said that after landing he suffered flulike symptoms and felt bad for many weeks, and that altered his cognitive performance. More troubling, in zero-g, about two liters of fluid shift from the lower half of the body to the upper half, leading to pressure on the optic nerve and changes in the shape of the eyeball and the integrity of the retina. Another enduring change, scientists found, was a collection of genetic mutations that Kelly gained in space. "However, with only two people in the study, we're limited in the conclusions we can draw about the effect of space travel on the genome".

That wouldn't be an option on a three-year trip to Mars. Kelly's near-year is the record for an American.

What is unknown is exactly why space travel impacts age and health.