Inspiration Mars is an appropriately named proposed mission to Mars with the goal of inspiration rather than actually landing on Mars (perhaps oddly). The proposed journey is set to embark in 2018, and take 501 days for a round trip coming within 100 miles of the red planet. The trip will have two passengers, a man and woman, preferably of older age so as to avoid the potential risks radiation has on insemination and child birth. The dangers of radiation exposure are myriad, so to help mitigate said exposure, the ship will be lined with food, water, and poop. Specifically, poop from the astronauts that will be riding in the craft.

On a spacecraft, there isn’t exactly a plumbing system that leads to a large plant somewhere upstate, so there isn’t anywhere for urine or fecal matter to go. A member of the Inspiration Mars planning team, Taber MacCallum, said that human waste makes great radiation shielding, so it’ll be stuffed into bags and then lined along the walls of the ship. As an appetizing bonus, the waste will be dehydrated, so the wastewater can be recycled for drinking. The beginning of Waterworld doesn’t seem so silly now, does it?

Along with the literal bags of poop, food will pushed up against the craft’s walls as well, but wouldn’t become radioactive, as it would simply block the radiation rather than absorb it. That said, we can only hope the food wouldn’t be sharing a wall with the poop bags. The crew’s drinking water will also be used as shielding, as nuclei block cosmic rays, and water has more nuceli-per-volume than metal does.

The waste that will line the walls of the craft creates a layer that is 40 centimeters thick, and would initially be filled with drinking water. The bags would then be filled with the waste as the water levels dwindle.

If you live in a big city, you might be used to eating on the run, or at least outside at a cafe’s extra seating or on the steps of your office building. Every now and then, you end up in visual or olfactory range of something quite unappetizing, like rats or, quite frankly, puddles of urine. You might find it difficult to eat something perfectly edible while that unappetizing sight or smell is nearby. In a small spacecraft filled with bags of poop and pee, this is actually a legitimate concern. While opaque bags can be used to remove the sight of human waste, the smell might be much more difficult to control, and is something on which the team is currently working.