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UCSD: Twin Astronauts To Reveal Health Impacts Of Space Travel

Research into the health impacts of long-duration space travel will kick into high gear next week when astronaut Scott Kelly returns from an 11-month stint on the International Space Station, UC San Diego scientists said Friday.

While he's been in space, his twin brother Mark has been earthbound, giving researchers an opportunity to compare various aspects of their health, according to UCSD. Scott's mission provides researchers with the unprecedented opportunity to compare data from two genetically identical people who have spent a long period of time in vastly different environments.

Over the past almost one year, both Scott and Mark have had their visual acuity, cardiovascular function and other things tested. Scott Kelly has also taken blood and urine samples, and they'll be brought back to earth separately for comparison by NASA's Human Research Program, the National Space Biomedical Research Institute and 10 investigative teams around the country, including UCSD.


"NASA's priority is to maintain crew member health throughout long duration missions," said Brinda Rana, a professor in the School of Medicine's Department of Psychiatry and principal investigator on the UCSD part of the study.

She said researchers want to understand how extended space flight affects an astronaut's cognition; heart, eye and immune function; the bacteria that live in the gut that make up the microbiome; and the so-called "omics" profiles — their genomics, proteomics and metabolomics.

"Our studies will provide important data on how the space environment impacts the human body at the molecular level so that NASA can identify risk factors and countermeasures for possible health issues induced by prolonged space travel, such as a mission to Mars," said Rana.

She plans to focus on identifying metabolites and proteins in the twins' blood and urine that can serve as biomarkers — biological indicators that display early signs of cardiovascular, vision and other possible physiological problems.

Metabolites are small molecules that are naturally produced byproducts of the body's processes and include sugars, vitamins, amino acids and other substances. A balance of metabolites in blood and elimination in urine is important for maintaining health, according to UCSD.


NASA and astronauts have long known that traveling through space, with its microgravity, radiation exposure, isolation, confinement and elevated carbon dioxide — which can happen on space vehicles — can produce potentially adverse side effects.

"Our bodies are adapted to a 1g environment in which gravity pulls the blood toward the feet," Rana said.

"In space, with nearly zero gravity, the blood and other fluids in the body shift upwards toward the upper body around the heart, the neck and the head," Rana said. "This fluid shift may cause changes in brain pressure and vision, which have been observed in some astronauts."

Thus far, space missions have flown for relatively short periods, most lasting less than six months. Scott Kelly's visit to the ISS is the longest an American has spent in space.

Future NASA destinations under consideration, such as Mars or asteroids, will require much longer periods in an unearthly environment, maybe 30 months or longer.

In interviews over the last few days, Scott Kelly said a trip to Mars is possible, and that he could spend another 100 days in space. He and his mission partner, cosmonaut Mikhail Kornienko, are due to return to earth Tuesday.

The researchers, who say their findings could have applications for more grounded earthlings, hope to complete their studies by December.