Imagine you are Bob Behnken or Doug Hurley (NASA astronauts) struck in a 6-hour spacewalk in your spacesuit, and feeling the urge to pee.
So do astronauts wear diapers for peeing? NASA Astronaut Mike Mullane explained that male astronauts choose to either wear space adult diapers called Maximum Absorbency Garments (MAG) or wear a urine-collection device. The space diaper can collect 900cc (around 3 soda cans) of urine and poop during a spacewalk or landing.
Historically, Apollo astronauts wore space diapers in their suits, which NASA called Maximum Absorbency Garments (MAG). PBS shared more about space diaper in a video by women astronauts.
The MAG is worn under the spacesuit and provides for the hygienic collection, storage, and the eventual transfer of astronaut urine and feces discharged during extravehicular activities
Mike Mullane further shared with Men's Health that the urine-collection device is much cleaner than the diaper but you cannot confirm or feel whether it is there. To pee in a diaper during spacewalk or landing, he just had to elevate his legs. Therefore, it is safer for an astronaut to wear diapers as gross and uncomfortable as it is.
According to former NASA astronaut and current SpaceX consultant Garrett Reisman, "I can tell you from personal experience, and data collected by NASA — its kind of like going on a camping trip, in the sense that, for the first 24 hours, your body kind of shuts down a little bit as far as the digestive system goes," Reisman told Space.com. "So, I guess where I’m going with this is, I don’t think there's going to be a whole lot of pooping on Dragon.”
Astronauts urinated into a "relief tube" (designed only for male astronauts, since NASA only employed male astronauts at the time) which emptied into a bag and did the rest of their "business in bags that they had to knead, roll up, and take back to Earth to be tested. (Source: Space.com)
During the initial days, Disposable Absorption Containment Trunk was used first before the invention of MAG.
Disposable Absorption Containment Trunk
The DACT are like pads and first used during the 1983 Challenger mission to address the needs of women since they were leak-resistant, manageable, and comfortable.
Most astronauts get an enema before launch to clear their pipes so they don't have to do anything other than pee aboard the tiny, privacy-free space toilet, NASA astronaut Leroy Chiao wrote for Gizmodo.
Space Toilet
Besides the long hours during landing and spacewalk, astronauts could urine without diapers in a space toilet.
In International Space Station, the space toilet recycles 93% of the urine for an astronaut for drinking. This reduces the ISS's dependence on water.
Besides urine, sweat had to be recycled. NASA shared that Astronaut Scott Kelly will drink 730 liters of recycled sweat and water in time.
For poop, it gets collected onto an uncrewed space ship that jettisons from the space station and burns up as it returns to Earth also known as "burning poop."
SpaceX who sent Bob Behnken and Doug Hurley to the ISS in 2020 also invented a new waste removal system in the Crew Dragon capsule. However, the details are not available and only will be shared during its return.
Poop and Urine in Moon
Besides diapers and space toilets, human waste can be found in the Moon. Apollo 16 astronaut Charlie Duke spent 71 hours on the moon in 1972. On a recent phone call with Vox, he confirmed that the Apollo crew left human waste behind in the moon.
“We did,” he says. “We left urine that was collected in a tank ... and I believe we had a couple of bowel movements — but I’m not sure — those were in a trash bag. We had a couple of bags of trash we kicked out on the lunar surface.”