On a two-year trip to Mars, according to one estimate, a crew of six humans will generate more than six tons of solid organic waste–much of it feces. So what do you do with all that? Right now, astronaut waste gets shipped back to Earth. But for long-term exploration, you’d want to recycle it, because it holds resources that astronauts will need. It will provide pure drinking water. It will provide fertilizer. And, with the help of a recently discovered microbe, it will also provide electricity.