Leaving this planet does some very weird things to the human body. Burping, for instance, becomes a real mess, because gravity isn't pulling the rest of your stomach contents down as the air rises through your esophagus.

So, in space, burps come with liquid bonus features. There are other more serious issues too, like muscles atrophying because they aren't resisting the pull of gravity anymore. And vision suddenly becomes blurry, and immune systems that go totally haywire.

The fact is, we still don't have a handle on exactly what happens to us in space, when we're exposed for long periods to weightlessness, cosmic radiation, changing sleep cycles and isolation.

So, when US astronaut Scott Kelly heads to the international space station in March, NASA is hoping to do a lot more research, because Kelly and his mission partner Mikhail Korniyenko will be undertaking an historic, record-breaking mission: They'll be in space for an entire year.

We usually don't send people into orbit for more than six months or so at a time. So this new mission will be a great opportunity to find out more about the effects of long term stays in space.

But, the subject of the research won't just be Korniyenko and Kelly themselves. Turns out, Scott Kelly has an identical twin brother, Mark, who's a retired astronaut himself.

This means that for the first time, we'll be able to see what happens to a person when he goes to space and compare him to another person with identical DNA back on earth.

Obviously, the opportunities for research here are practically limitless. So NASA scientists had a hard time narrowing down their studies down to just ten major areas.

For example, we know that the human immune system goes wonky when we're in orbit. It sometimes doesn't respond to threads as well as it should, but other times, it gets way too aggressive.

To figure out why and how this happens, researchers from Stanford will give both twins flu shots before, during, and after the mission.

By monitoring how the immune systems respond to the vaccinations, the researchers hope to learn more about how the body responds to viral threats in space.

Another study will look into the problems that many astronauts experience with their body fluids. All sorts of things are circulating in our bodies after all: blood, lymph, cerebrospinal fluid, and normally, our bodies compensate for the pull of gravity by working extra hard to make sure that these fluids get pumped up toward the brain.

When astronauts go to space however, that downward pull is gone, but their bodies keep compensating for the force that isn't there. As a result, cerebrospinal fluid can end up collecting in the astronauts heads, creating symptoms ranging from what feels like a horrible head cold to pressure behind the eyes, causing blurred visions.

So, researchers from the University of California will track changes in the proteins that control the production of these fluids and their transport.

Since proteins are build according to the instructions coded in DNA, using identical twins will eliminate any differences that are caused by genetics.
 
Another experiment by John Hopkins University will analyze the twins' entire genomes, and look for changes that happen in Scott's genomes compared his brother's over the course of the missions.

Those changes will help researchers understand the epigenetic effects of space flight, which are changes in the genes that are caused by the environment, in this case low-gravity, high radiation environment.

Other studies will be more general, like a study from the University of Pennsylvania, that will use a battery of tests to look for changes in cognition.

Another from Northwestern University will even look at the different types of bacteria that inhabit the twins' digestive systems, and see how space travel affects them.

The hope is, that by better understanding of these changes, scientists will be able to control them, making even longer missions to asteroids, to Mars and beyond, much safer. It may find even a way to make space burps worry free.

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