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What Did a Year in Space Do to Astronaut Scott Kelly? And What Does It Mean for a Trip to Mars?

astronaut scott kelly on earthFor the past year, NASA has been conducting an experiment that is—quite literally—out of this world! And this week, that experiment came to an end.

One year ago, astronaut and identical twin Scott Kelly shot up to the International Space Station while his identical-except-for-the-mustache twin, retired astronaut Mark Kelly, stayed firmly planted on Earth. And now, after 340 consecutive days in outer space, Scott is finally coming home to Earth. But now the big question is—what has a year in space done to Scott Kelly? And what does it mean for NASA’s plans to go to Mars?

A year is twice as long as the typical ISS trip—but it is how long astronauts will have to spend in interplanetary space to get to Mars and back. That’s one year for the body to slowly break down in space thanks too little gravity and too much radiation. So, for the past year, both Scott (in space) and Mark (on Earth) have been sending all kinds of samples to NASA. And we do mean all kinds of samples—blood and urine, saliva, and even poop—for science! By comparing the data, scientists hope to get a better handle on what happens to human bodies in space. explains some of the effects that microgravity can have on the human body while in space. Some of these effects are obvious. When bones and muscles no longer have to bear the weight of walking, they start to weaken. Bones thin, muscles atrophy. To counteract that, ISS astronauts spend an average of two hours a day exercising, strapped onto a treadmill with elastic bands or doing weight resistance training. Supplements like vitamin D also seem to help.

Less obvious are the effects of gravity on internal fluids—like blood and urine, or all the interstitial fluid between the cells of your body! Without gravity, for example, the heart shrinks because it no longer has to work as hard to pump blood to the legs and back. It also accounts for the Charlie Brown effect, where fluids in the face make astronauts more round-cheeked than they typically are on Earth. This makes it harder to smell food, but more seriously, also harder to see. To counteract some of this, NASA has a device called a chabis, basically an uncomfortable-looking pair of pants that pull fluids back down to the legs.

The big risk of travelling into deep space is the cosmic radiation that stars and other astronomical objects give off, and this still remains a big danger for astronauts. The ISS sits low enough in Earth’s orbit that it still enjoys some protection from the Earth’s mass and magnetic field; however, once astronauts travel out into open space en route to Mars, radiation becomes an even more pressing problem. NASA needs to find out exactly how big a dose of space radiation is dangerous before attempting to send their scientists into the dark corners of outer space.

But all of that negativity aside, the good news is that astronaut Scott Kelly is now home! He has been reunited with his loving family and, just as importantly, his identical twin Mark. And even though most of the data collecting for this wacky outer space twin study will be over, the real science of analyzing the two men has only just begun!

Photo credit: Associated Press via PBS

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