When NASA sends astronauts back to the Moon, they’ll need a place to go to the bathroom when they reach the lunar surface. And in order to create the best Moon toilet the Solar System has to offer, NASA wants to hear from members of the public who might have ideas on the best way to manufacture an easy-to-use lunar restroom.

Today, NASA is announcing the “Lunar Loo Challenge,” a competition in partnership with HeroX to come up with the best space toilet for the agency’s future human lunar lander. As part of NASA’s Artemis program, which aims to send the first woman and the next man to the Moon by 2024, the lander will take astronauts from lunar orbit down to the Moon’s surface. That means the restroom on board has to be versatile: it will need to work in orbit, where the astronauts will be weightless, and also when astronauts are experiencing one-sixth of Earth’s gravity on the lunar surface. And without much gravity, things can get a little messy if you don’t prepare.

After more than half a century of sending humans to space, NASA has gotten pretty good at building space toilets. But the agency wanted to look outside the box, especially since bathroom technology has advanced a lot here on Earth. “We wanted to see what’s out there — what the unknown unknowns are and put the power of the crowd to find those citizen scientists who’ve got different perspectives,” Mike Interbartolo, project manager for the Lunar Loo Challenge who is working on the Human Lunar Lander System at NASA, tells The Verge. NASA plans to award up to $35,000 in prizes, and some form of the winning space throne may be included on the lander.

The Apollo Urine Transfer System, which used a rubber tube that attached to a hose.
Image: NASA

Whatever NASA and the public come up with, it will likely be way better than what the Apollo astronauts had at their disposal. The Apollo spacecraft that took humans to the Moon didn’t have any toilets at all. To urinate, they had to pee into a rubber tube (which basically worked like a condom) that transferred the liquid either outside the spacecraft or into a storage container. Pooping was even worse. The crew had to use plastic bags with sticky rings around the rim, which attached to their behinds.

“It was messy,” Interbartolo says. “You didn’t have any odor control. The crew hated it. It wasn’t easy to get a good seal on the bag without your buddy having to help. And that’s just not the way we want to go back to the Moon 50 plus years later.”

NASA’s facilities have definitely evolved since then. There are currently two toilets on the International Space Station, both of which rely on suction. To go No. 1, astronauts pee into a cup attached to a hose that has a fan system inside, creating suction that pulls the liquid into the hose. For No. 2, astronauts “squat” over a white seat with a hole that attaches to a storage container; the same fan system is used to help to make sure the poo actually goes inside the hole. Though that can also be a challenge. “It’s pretty small, so you have to have pretty good aim,” NASA astronaut Suni Williams once said during a video touring the toilet.

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NASA also plans to test out a new toilet on the space station later this year. Called the Universal Waste Management System, the toilet will eventually be used in the agency’s future Orion spacecraft, which will take astronauts to lunar orbit. But NASA wants something a little different for the lander. ”All those toilets are primarily microgravity toilets,” Interbartolo says. “They don’t have to worry about going down into a gravity well and coming back up again, like a lander does.”

NASA expects it could take between 20 to 24 hours for the lander to travel from lunar orbit down to the surface. “So that’s obviously outside the realm of them just holding it in or using a diaper in their spacesuit,” Interbartolo says. The astronauts will then spend potentially six and a half days on the Moon, and a toilet will become even more necessary at that point. Interbartolo says this new lunar lander toilet might shift to a different position or functionality when on the Moon’s surface and then shift again when in weightlessness.

To win the best Lunar Loo design, participants need to follow a series of specifications laid out by NASA. The toilet must be able to accommodate both women and men since this will be the first time a woman steps onto the surface of the Moon. The toilet has to be a certain size and weight; it can’t use up too much energy, and it can’t be too noisy. It also can’t be too time-consuming to use.

But perhaps the best specifications relate to how much waste the toilet must be able to collect. NASA did a lot of research to determine just how often astronauts will need to go on the Moon. So the agency wants a toilet that can collect up to “1 liter of urine per use,” and “accommodate 500 grams of fecal matter per defecation.” The toilet must accommodate all sorts of fluids, including period blood, as well as vomiting and diarrhea from a sick crew member. Above all, resiliency is key. “We want to make sure it has enough redundancy so that if there’s a failure in the toilet, it doesn’t spread fecal matter or urine all over the cabin and contaminate things,” Interbartolo says.

An artistic rendering of Blue Origin’s proposed lunar lander.
Image: Blue Origin

In addition to the main challenge, there’s also a junior competition for kids under the age of 18 to submit designs. A panel of NASA engineers will ultimately decide which toilet submitted through the main competition works best. In addition to winning money, winners will get a tour of NASA’s Johnson Space Center in Houston, Texas, and the opportunity for some version of their toilet to be used by actual astronauts. “We’ll have some follow on discussions to make sure we fully understand their design concept and ask any questions,” Interbartolo says. “But after that it’s up to the NASA design team to take the technology concept and run it to ground.”

Right now, NASA doesn’t know the exact lunar lander it’s taking to the Moon. In April, NASA gave contracts to three companies — SpaceX, Blue Origin, and Dynetics — to develop lander design concepts. But whichever design gets chosen, NASA will be in charge of the toilets. “At this point the toilet is considered NASA government furnished equipment, so it was always planned that NASA would provide a toilet waste management system,” Interbartolo says. However, if one of the private companies really wants to create their own toilet, NASA will work with them on that. SpaceX recently developed a toilet for its Crew Dragon spacecraft, which takes astronauts to and from the space station (though the company won’t go into details about the toilet publicly).

Of course, the agency’s primary focus is actually building the lander hardware that will take humans to the Moon, which is nowhere near ready yet. But while private companies and NASA continue to toil away at the spacecraft needed for lunar travel, they hope the public can help out with this key aspect of sending humans to space. “Going to poop on the Moon is not a top priority, but we don’t want to make it a miserable experience for the crew,” Interbartolo says. “We want to make it as comfortable and as close to home life as possible.”