What it's REALLY like to be a NASA astronaut living in space for a year

That's one of the questions NASA astronaut Scott Kelly and companion Russian cosmonaut Mikhail Kornienko have set out to answer during their year-long mission on board the International Space Station (ISS).

If the men succeed in their mission to discover how a long-term, low-gravity environment affects the human body, they'll be the first humans to ever spend a full year in zero gravity, which is twice as long as typical US missions. Their journey of more than 143 million miles is critical in preparing astronauts for future expeditions to Mars.

So far, Kelly and Kornienko have spent more than 300 continuous days aboard ISS, and Kelly shared some interesting observations so far during a Reddit AMA this weekend.