On March 1st, 2016 we learned about

Kelly and Kornienko return from 340 days of studying how our bodies survive living in space

As I write this, three astronauts are in a controlled descent towards the Kazakhstani desert. For two of them, it will be the first time they’ve touched the Earth in 340 days, having spent twice the normal amount of time astronauts are deployed living on the International Space Station (ISS). As such, they’ll be met not only with warm greetings, but also with a battery of tests, ranging from walking in a line to getting off the ground from a prone position. While the three men conducted various experiments on the ISS, this unusual time in orbit made American Scott Kelly and Russian Mikhail Kornienko the premier experiments of the mission.

While Kelly and Kornienko spent an usual amount of time on the ISS, they were there to help us prepare for journeys when a year-long voyage is the norm. Under optimal conditions, a one-way trip to Mars will likely take a around a year to complete, which means that future astronauts will need to be prepared for environments the human body has not evolved to cope with. Even allowing for climate controlled vehicles, microgravity and higher radiation exposure in space seem to pose challenges to our physiology.

Adjusting to life off the Earth

Microgravity, as experienced on the ISS, hits the body in a number of ways. The ease of floating everywhere deprives muscles and bone of the exercise and resistance that normally strengthens them. Even with two hours of exercise in weighted belts each day, astronauts all show a notable loss of muscle and bone density. Fluids normally subject to the pull of the Earth are allowed to float around more, which leads to puffier cheeks, but more seriously, additional pressure on the optic nerve in the eye. Both conditions have been found even after shorter visits to space, so Kelly and Kornienko will surely show similar symptoms.

Astronauts also face additional exposure to radiation. While we are all hit by radiation every moment of our lives, the Earth, it’s atmosphere and magnetic field all provide a degree of shielding that mitigate our exposure more than an astronaut can count on. The goal of subjecting Kelly and Kornienko to a longer voyage in this case would be to help understand how aggressively shielded future spacecraft need to be. Radiation shielding generally adds weight to a ship, which then makes them harder to get off the ground. Any changes in health will be watched for years to come, and in the case of Commander Kelly, compared to the health of his twin brother, Mark Kelly, who will act as the best control NASA could hope for.

Beyond being lab rats

While their health was monitored closely, Kelly and Kornienko did more than subject themselves to tests. Both men were veterans of the space program, and conducted a variety of experiments, including growing plants for consumption and at least one impromptu space-walk to repair the ISS. It’s likely their last time in space, but Kelly said that after this long he feels like he’s been on the ISS his whole life. He’s not bringing any new souvenirs back that he hadn’t brought up with him, aside, of course, from the cache of data contained in his body’s experience.

We’ll learn more about the effects of living in space in the coming years, but for now, as the screen in the Russian command center reads “Есть Посадка!” (we have a landing!) it’s time to just welcome these guys home.

Source: What Did a Year in Space Do to Scott Kelly? by Sarah Zhang, Wired

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