It's something many earthbound people have surely wondered about over the years: how exactly do astronauts use the toilet? After all, one of the most fundamental of human activities is actually a pretty major obstacle in a low or no gravity environment, given both the waste produced and the more practical issues of simply 'going' in the first place.

In the video below, ESA astronaut Samantha Cristoforetti walks viewers through the elaborate lavatory on board the International Space Station. She explains the devices involved, and the different procedures necessary for a 'number one' and a 'number two'.

As Cristoforetti points out, urine is recycled on board the ISS. That's in order to cut down on the amount of water delivered to the station - although obviously it goes through a complex filtration and processing system before being used again. 

Check out the clip below. It's a must watch for those whose knowledge of space toilets pretty much amounts to that inspired gag in 2001: A Space Odyssey.

And in the video below, the Italian astronaut takes viewers on a tour of a space bathroom: