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So, you want to be an astronaut. Well, one of the many surprisingly difficult things you're going to have to learn is how to do your business in space, by which I mean, like, peeing and pooping and stuff.

As you might imagine, it's a little bit tricky and training begins well before you strap in for that trip to the international space station. Learning how to defecate in a microgravity environment, first of all, is the opposite of glamour. On Earth, we sit on a toilet seat that's between 30 and 45 cm in diameter. In space, you'll be working with an opening that's about 10 cm wide because, you know, you want to make sure that it all stays where you put it. So NASA has learned overtime -- and I don't want to know how -- that the best way to train astronauts for this is by installing a camera inside the toilet, allowing astronauts to watch on a nearby monitor as they figure out how best to position themselves and avoid any unfortunate mishaps. Once they master that part of the process, astronauts use restraints to help keep them in place so that you don't float away while you're doing your business.

The toilet itself works like a vacuum cleaner using differential air pressure to suck the solid waste away. That waste is then stored for the remainder of the mission. And, yeah, it could be jettisoned down into space but ISS officials have decided it would be best not to have astronaut poo orbiting the Earth at 28,000 km/hr along with all the other space junk up there. 

Urinating meanwhile requires an entirely different contraption. Each astronaut gets his or her own personal urinal funnel which is attached to a hose adapter. Fans suck the air and the urine out and into a waste water tank. Naturally, there are different set-ups for male and female astronauts, and it's actually easier for the women. They can place the top of their funnels directly against their bodies which adhere to them and then the suction is turned on. Male astronauts need to be a bit more careful though. They have to hold the funnel cone close enough that it will collect the urine but not so close that they get vacuumed in when the toilet's pressure is activated.

Though this sounds like pretty simple equipment, the ISS toilets are not cheap. The newer versions cost about 19 million dollars. Until recently, all collected urine was released into space when the waste water tank filled up. That changed though in 2008 when astronauts and cosmonauts aboard the ISS began to use a new system designed to purify or distill urine into water that could be used for drinking and bathing. 

Here on Earth, distilling water is a pretty simple process: boiling the water and then letting the steam cool and condense back into pure water. But it's a bit more complicated in space where the lack of gravity prevents contaminants in urine from separating from the steam, so the ISS creates its own kind of artificial gravity for this purpose, spinning its keg-sized distiller while boiling the liquid. The steam goes to the middle where it can be filtered out while the waste falls to the sides of the container. Despite some early kinks, the system works as astronaut Don Pettit said, "yesterday's coffee becomes today's coffee." 

So if it's so easy, why don't we do that on Earth? Well, the setup on the ISS costs about 250 million dollars, so, yeah. But now that they're getting the hang of things, scientists are trying to take the process a step further by using urine to generate electricity in addition to drinking water. NASA is currently testing a system that uses a process called forward osmosis which effectively pulls water out of urine using a concentrated solution of salt and sugar. The leftover nitrogen-rich waste from the urine can then be converted into ammonia which can be used as fuel for generators that make electricity. Now if we could only find something equally useful to do with our space poop. But, hey, now you know. That was fascinating; I hope you thought so. 

Thanks for joining me for SciShow Space. If you want to help us keep exploring the universe together, just go to subbable.com/scishow and don't forget to go to youtube.com/scishowspace and subscribe.