Is There Poop on the Moon? ft. Smarter Every Day

Apollo missions solved a problem most space stories ignore: how astronauts handled waste in a cramped, sealed command module without throwing off the spacecraft’s trajectory. In the Apollo 16 command module, fecal waste was collected using a taped-on plastic fecal collection assembly—essentially a bag astronauts attached to their bodies. Urine was handled differently through a urine transfer system built around a rubbery, condom-like interface connected to a metal tube. That setup could route urine either into a collection bag or directly out into space using a differential pressure valve.

The key engineering constraint was momentum. Any fluid expelled from the spacecraft changes its motion, even if the effect is small. The transcript highlights that releasing a few hundred milliliters of urine from a roughly 45,000 kg spacecraft would alter velocity by only a few hundredths of a km/h—but over a three-day trip to the moon, those tiny changes add up enough that mission control needed to be informed when astronauts stopped using the facilities. Waste management wasn’t just hygiene; it was navigation-aware operations.

Once on the lunar surface, the tradeoffs shifted again because mass and fuel were tightly limited. The lunar module’s ascent stage could carry only enough propellant for a return, leaving little room for extra weight. That reality shaped what happened to waste: astronauts left behind a lot of items on the moon, including drills, batteries, food containers, towels, cameras—and, inevitably, feces. The transcript frames the decision bluntly: bringing poop back would have meant sacrificing something else, and the ascent stage could only accommodate a few hundred pounds of additional mass.

The discussion then pivots from space-bathroom mechanics to a more personal, museum-based detail. A fecal collection assembly and a urine transfer bag are shown at the U.S. Space & Rocket Center, with the urine bag described as a 60-year-old item still preserved from the mission era. The segment also notes that NASA had already developed a “space toilet” by that time, and it teases an additional experiment filmed on the moon—presented as something still functioning decades later—before returning to the humor of breaking the seal on the preserved urine transfer bag. The overall takeaway is that Apollo’s bathroom system was a carefully engineered compromise between bodily needs, spacecraft dynamics, and the unforgiving physics of mass and fuel.