The last time humans landed on the lunar surface, in December 1972, they were all basically wearing diapers.

That’s because NASA never really bothered to design a proper toilet for the Apollo moon missions. Instead, astronauts peed into roll-on cuffs, pooped into bags, and used space diapers when they ventured out of the spacecraft in their big bulky spacesuits.

“Defecation and urination have been bothersome aspects of space travel from the beginning of manned space flight,” said an official NASA report on the Apollo missions published in 1975.

Nearly five decades later, as the US prepares to launch astronauts to the lunar surface by 2024, the space agency is hoping to do things a little more comfortably.

“The astronauts were adamant that they do not want to go back to the Apollo bags,” Mike Interbartolo, who’s part of NASA’s lunar-lander engineering team, told Business Insider.

So this time around, NASA is crowdsourcing a new toilet design for the Artemis moon lander, launching a “Lunar Loo” contest on HeroX.

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“We need a toilet that needs to work for seven days on the surface of the moon, as well as during that transit time to and from the moon,” Interbartolo said.

That means the toilet system must be functional in both the microgravity of space and lunar gravity, which is about one-sixth Earth’s gravity. The toilet must also be usable for all astronauts, regardless of sex — something the first space bathrooms decidedly were not.

Read more: Business Insider