It’s something we take for granted, but it’s resulted in some major headaches for NASA: the need of human beings to poop. As NASA turns its eyes toward an eventual mission to Mars, a months-long journey aboard a spacecraft means scientists will have to figure out what astronauts will do about their excrement.

Space is at a premium in the Orion spacecraft, especially for such a long trip, and every ounce counts. It’s why NASA has launched the HeroX competition to come up for solutions to “space poop,” awarding $30,000 for up to three good ideas.

It’s an issue that hasn’t cropped up with prior missions, because most have been short trips to the International Space Station in low-earth orbit. There’s a toilet on the ISS that uses a vacuum to suck up urine and fecal matter, which can be disposed of or turned into drinking water.

But if an emergency were to happen where the spacecraft lost pressure, astronauts would have no choice but to poop in their suits. That obviously would create a problem if there were months left in the journey when it happened.

NASA has introduced some mitigating measures. One is a high-calorie food bar that would great limit the amount of waste the body produces. “When you have 700 to 900 calories of something, it’s going to have some mass regardless of what shape it’s in, so we’ve taken a look at how to get some mass savings by reducing how we’re packaging and stowing what the crew would eat for breakfast for early Orion flights with crew,” said Jessica Vos, deputy health and medical technical authority for Orion, in a statement. “When you think about multi-week missions in Orion, having just one package for breakfast items for crew will help us limit the space we need to store them.”