People are very messy creatures. For example, within every 27 days we shed our skin and it’s replaced with a new layer. If you’ve ever sneezed then you know of more stuff coming from our bodies. And of course there’s digestive waste. About that, the single most common question to astronauts is about going to the toilet in space. None of these are issues on Earth as they are part of the natural cycle and the messes get naturally recycled.

Now imagine being in a lunar colony. There is no natural environment. Everything about you has come from Earth at an exorbitant cost. The costly food you eat and the costly water you drink every few hours will get processed in your stomach and the waste excreted out. On the ISS, the waste is simply discarded and burnt during re-entry of the garbage container. On the Moon, that option is not available. So either the lunar colony will grow a mound of biological waste or it will have a cycle of its own to turn the waste into something useful.

Yet on Earth there’s a similar problem. Mainly, there’s so many people that the natural cycle can’t deal with all the waste. An indication of this is the Swachh Bharat Mission in India that’s aiming to stop open defecation. Perhaps if you live in a city and gone on a wilderness hike then you’ve had a similar challenge? What to do to keep nature natural while still responding to one of life’s necessities?

Now joining these two issues; space toilets and open defecation may seem unlikely. But there is a similar need. That is, humans need to clean up their messes rather than just walk away. Can you think of something that will address both? Tell us! Or talk with ESAs Space for Sanitation program. Or the USAs Universal Waste Management System (UWMS). And with it we can reduce the messes that we leave behind.