Of all the endless wonders of our universe, from the distant twinkling stars to the promise of alien life forms, one of the most common questions about NASA's missions into space is all about humankind's most basic function.

In a very... uncomfortable video, National Geographic's "Known Universe" tackles the question of how exactly astronauts use the bathroom while in space. With star travelers floating through their gravity-free environment, the question surely is a curiosity. And while a comedic fantasy might involve byproduct bouncing lightly through the cabin, the reality is a lot more cold and precise.

Let's just say it involves switches, levers, nozzles, hoses and vacuums. And that answering nature's call isn't exactly the best part of traveling the great beyond.

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