When you're on a budget-conscious mission to Mars, you can't waste anything—including your own, well, waste. The lucky couple tapped for Inspiration Mars' private voyage to the red planet will be tasked with lining the walls of their vessel with their own poop to shield themselves from cosmic radiation, a team member tells the New Scientist. It gets even more stomach turning: all waste will first be dehydrated so that the water can be recycled for drinking.
"It's a little queasy sounding, but there's no place for that material to go, and it makes great radiation shielding," the team member says. "Those solid waste products get put into a bag, put right back against the wall." Of course, it might be a while before there's enough poo to line all the walls, so food and water will also be used as radiation shielding.