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Their Mission: Studying What Outer Space Does to the Body

Astronaut Scott Kelly Astronaut Scott Kelly (Photo: Bill Ingalls/NASA/Getty Images)
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Astronaut Scott Kelly recently landed back on Earth after spending nearly a year on the International Space Station with Russian cosmonaut Mikhail Kornienko. The two men lived in outer space for 340 days — the longest continuous stay, according to the Los Angeles Times. In fact, Kelly has now spent a total of 520 days in space, more than any other U.S. astronaut.

That lengthy stay was the point of the mission. Kelly and his identical twin brother, former astronaut Mark Kelly (husband of former Arizona Congresswoman Gabrielle Giffords), are part of a scientific experiment to study the effects of long-term exposure to outer space and its zero-gravity conditions. Mark stayed back on Earth while Scott was in space.

“As we prepare to go all the way to Mars in the decade of the 2030s, there's going to be a lot that we're going to have to learn,” Senator Bill Nelson (D-Fla.), a former astronaut who spent six days on the space shuttle Columbia in 1986, said in a statement.

Scott Kelly echoed that sentiment in an interview with NASA TV after he landed in Kazakhstan. “I think that expanding our envelope and our ability to operate is something that will take us further from the planet,” he said. “Developing technology to do so is very important for our economy and our way of life.”

During Kelly’s time in space, both brothers provided blood, saliva and urine samples, had ultrasounds and bone scans and even got flu shots, according to Fox News. Once Kelly returns to NASA’s Johnson Space Center in Houston, scientists will examine him and collect more samples.

Health effects of life in space

Scientists already know some of the effects that microgravity has on the body. For example, in space, blood gets redistributed, with more accumulating in the upper half than in the lower extremities, according to the National Space Biomedical Research Institute (NSBRI). For this reason, astronauts usually have a puffy face while in space, and their legs are smaller in circumference.

Brinda Rana, PhD, a molecular geneticist at UC San Diego who is involved in two of the 10 research projects, told the LA Times there are more concerning health issues related to this fluid shift, including the raising of intracranial pressure, visual impairment and inflammation potentially linked to cardiovascular disease.

Other ways living without gravity changes your body:

  • It weakens your muscles and bones. In microgravity, you float, so your bones and muscles (especially in your legs, hips and back) aren’t bearing as much weight as they normally would, NSBRI says. This leads to bones becoming brittle and weak. Muscles also become weak and can atrophy. Astronauts exercise in space to minimize the damage, but “nutritional interventions designed to reduce the muscle loss may one day be added as a complement to the exercise program,” NSBRI says.
  • It makes you taller. On Earth, gravity compresses the space between disks in your spine. In space, the lack of gravity makes the space expand, making you taller, the NSBRI says. Back pain may be a possible side effect.
  • Your heart may get smaller. Your heart doesn’t have to work as hard in a zero-gravity environment, according to NSBRI. Over time, this may lead to a decrease in the size of the heart. “There is also a concern that space radiation may affect endothelial cells, the lining of blood vessels, which might initiate or accelerate coronary heart disease,” the NSBRI says.
  • It affects your balance. In space, the inner ear, which is sensitive to gravity, doesn’t function the same way it does on Earth. Because of this, astronauts may feel motion sickness or a loss of a sense of direction once they arrive in space. Once they get back to Earth, they may have trouble balancing, standing up or steadying their gaze. The longer people are in space, the NSBRI says, the more exaggerated these effects are.
  • It changes your sleep. The stress of being in space, the loss of a 24/7 light cycle and the need to adjust your internal body clock can all negatively affect sleeping. The NSBRI says scientists hope to help astronauts increase alertness through improvements to spacecraft lighting and shift schedules.

Related: America, Home of the Sleep-Deprived?