Whenever people meet astronauts or visit spaceflight facilities like the Johnson Space Center, one of those standard boilerplate questions that always gets asked is, "How do astronauts go to the bathroom in space?" Most people already know the gist - it's somewhat cumbersome and there's suction involved, as well as the perilous hazard of an ungodly mess in zero-G if done incorrectly. But given the two recent announcements in off-world toilet technology, 1) the International Space Station is getting a new toilet installed later this year (link here), and 2) NASA is seeking public input in designing the next-generation toilet to be used on the moon for the Artemis Program (link here), I believe a detailed history of cosmic commodes is in order!!

The history of American space toilets definitely didn't get off to an auspicious start. In 1961, Alan Shepard found himself strapped to his Mercury-Redstone rocket aiming to be the first American in space, but as his suborbital flight was only expected to last 15 minutes, the engineers didn't bother providing him a diaper or some other waste management system. After hours of launch delays with no method of relief, Shepard pleaded with Mission Control to let him out of the spacecraft ("Man, I gotta pee"), and although fellow astronaut Gordon Cooper dutifully relayed his request up the chain of command ("Look, the man has got to go"), it was emphatically denied by Wernher von Braun himself. So instead, Shepard told Mission Control he would simply pee in his suit despite concerns he might short circuit the medical sensors, and soon after, an audible "ahhhhhhh" emanated over the intercom. His suit dried before he finally launched, but what an ignominious way for America to send its first astronaut into space!

By the time the Space Race was in full swing, mission planners were far more thoughtful regarding waste collection on Gemini and Apollo missions, but the procedures were still anything but graceful. Michael Collins provides a fantastic description of what waste collection was like: in his autobiography Carrying the Fire, he explains in great detail the 20-step procedure (holy cow!) involved in using the Chemical Urine-Volume Measuring Subsystem (CUVMS):

Collins also describes the enormous entertainment the astronauts all got from the overboard urine dumps in space. Since the urine freezes immediately, the yellowish crystalline particles would whiz past the spacecraft windows in a display that astronaut Wally Schirra dubbed as the constellation "Urion"

And if that weren't unpleasant enough, Collins' description of pooping in space is even more comically barbaric:

"It was bad enough to have to unzip your pressure suit, stick a plastic bag on your bottom, and defecate - with ugly old John Young [his crewmate on Gemini 10] sitting six inches away!"   

The advent of the Space Shuttle's Waste Collection System brought some slightly improved comforts, such as a vacuum exposure system to kill bacteria in solid waste and prevent odor problems, airtight bags to hold used toilet paper, and detachable urine receptacles adapted for both male and female astronauts (NASA picked its first female astronauts in 1978). In fact, female astronauts have tended to have an easier time with the liquid waste adapter than their male counterparts: the men have to hold the tube's cone at just the right distance - close enough to catch the urine, but not so close that the suction vacuums them in! "We do not want men docking," says NASA crew habitability trainer Scott Weinstein

Nowadays, the International Space Station features two space toilets, one on the Tranquility module of the American side derived from the Space Shuttle's toilet, and one on the Zvezda module of the Russian side. I found astronaut Scott Kelly's book Endurance provides the most detailed and humorous account of the orbital laboratory's facilities, particularly since he spent so much of his famous year in space struggling with the insolent water closet:

The new toilet NASA is sending up, dubbed the Universal Waste Management System (UWMS), incorporates the crew feedback from numerous ISS expeditions over the last two decades in an effort to build a more compact, more reliable plumbing system capable of recycling more water and preventing microbial cross-contamination. As NASA looks to send people back to the moon and onward to Mars, future space toilets must be self-sufficient, as reliance on constant repairs or water resupply are simply impossible on deep space missions. Here are the specifications NASA set forth to the public for its Lunar Loo challenge: