The Apollo Waste Management Problem: Human Biology vs. Zero Gravity

Here’s a question that aerospace engineers at NASA had to solve with a straight face and a government contract: how do humans go to the bathroom in zero gravity, inside a spacecraft the size of a car, while wearing a spacesuit, for up to two weeks?

The answer, arrived at after years of development and millions of dollars, was: badly. The Apollo Waste Management System was by nearly universal astronaut consensus the worst part of going to the Moon. Worse than the risk. Worse than the confinement. Worse than the freeze-dried food. The toilet situation was so awful that some astronauts deliberately modified their diets for days before launch to minimize the need to use it.

The Urine Collection Device: The Easy Problem

Urine collection was the straightforward half of the equation, relatively speaking.

Each astronaut was fitted with a Urine Collection and Transfer Assembly (UCTA). During suited operations, this was essentially a condom-like sheath connected to a collection bag worn inside the suit. The sheath came in three sizes, though NASA diplomatically labeled them “small,” “medium,” and “large” rather than any anatomical description.

There was a persistent and well-documented problem with astronauts selecting sheaths that were too large, which caused leakage. NASA eventually relabeled the sizes to “large,” “gigantic,” and “humongous” to accommodate crew ego while ensuring proper fit. This is a real thing that actually happened.

When unsuited in the Command Module, astronauts used a hose-and-bag system that connected to the urine dump system. Collected urine was periodically vented overboard through a dump nozzle in the spacecraft hull. The urine immediately froze and sublimated into a cloud of ice crystals that dispersed into space.

Astronauts consistently described urine dumps as one of the most visually spectacular sights of the mission. The cloud of ice crystals caught the sunlight and sparkled against the blackness of space. Wally Schirra reportedly called it “the most beautiful sight in orbit.”

The dump nozzle itself posed an engineering challenge: it had to vent fluid to space without allowing cabin atmosphere to leak out, and it had to prevent ice from forming and blocking the nozzle. A heater element kept the dump port above freezing temperature.

The Fecal Containment System: The Hard Problem

And now we arrive at the engineering challenge that nobody wanted but everyone needed to solve.

The Apollo Fecal Containment System (FCS) was, in the bluntest possible terms, a plastic bag that taped to the astronaut’s buttocks. That’s it. That’s the system. The most technologically advanced space program in human history sent men to the Moon with a plastic bag and some tape.

The bag was a multi-layered affair, about the size of a standard kitchen garbage bag. It had an adhesive flange that stuck to the skin around the buttocks, creating a seal that was, in theory, supposed to contain everything.

The procedure was as follows:

Remove clothing (in zero gravity, in a spacecraft with two other people floating nearby)
Position the adhesive bag
Complete the bowel movement (in zero gravity, where nothing falls away from the body)
Manually separate the waste from the body using the supplied tissues (a step that merits no further description)
Add a germicidal pouch to the bag and knead it into the waste to prevent bacterial gas production
Seal the bag
Stow the sealed bag in a waste storage compartment
Clean up

The entire process took approximately 45 minutes per event in zero gravity. On Earth, the same biological function takes most people three to five minutes.

The problems were legion. The adhesive didn’t always seal properly against skin that was sweaty, hairy, or both. Zero gravity meant waste didn’t fall into the bag—it floated, sometimes in unexpected directions. The germicidal kneading step was universally despised.

Frank Borman, commander of Apollo 8, called it “a miserable operation.” Jim Lovell described the waste management system as the single biggest quality-of-life problem on the spacecraft.

The Apollo 10 Incident

On May 22, 1969, during Apollo 10’s mission, the following exchange was recorded in the official mission transcript. The speakers are Commander Tom Stafford, Command Module Pilot John Young, and Lunar Module Pilot Gene Cernan.

Cernan: ”…Where did that come from?”

Stafford: “Give me a napkin quick. There’s a turd floating through the air.”

Young: “I didn’t do it. It ain’t one of mine.”

Cernan: “I don’t think it’s one of mine.”

Stafford: “Mine was a little more sticky than that. Throw that away.”

Young: “God almighty.”

And then, moments later, a second one appeared.

This transcript is from the official NASA records. It is not folklore. It is not embellished. Three highly trained test pilots were floating in a spacecraft 200,000 miles from Earth, trying to catch feces with napkins while denying ownership.

The incident perfectly encapsulates the failure mode of the adhesive bag system. The bags didn’t always seal. Sometimes they came loose entirely. In zero gravity, the consequences drifted freely through the cabin.

Chemical Warfare in a Small Cabin

Beyond the mechanical challenges, there was the gas problem.

Human digestion produces gas. In a sealed spacecraft with a volume of 218 cubic feet shared by three people, flatus was not merely a social inconvenience—it was a potential engineering concern.

The Environmental Control System’s lithium hydroxide canisters removed carbon dioxide but did nothing for methane, hydrogen sulfide, or other gaseous byproducts of digestion. These gases accumulated in the cabin atmosphere.

NASA’s food scientists attempted to address this by designing the space food to be as low-residue as possible—food that would be almost completely absorbed by the body, producing minimal solid waste and gas. This partially worked, but no diet eliminates digestive gas entirely.

The hydrogen gas produced by normal digestion also posed a theoretical flammability concern in the pure oxygen atmosphere. While the concentrations never reached dangerous levels, NASA engineers had to actually perform the analysis to confirm this. Somewhere in the NASA archives, there is a formal engineering study on the flammability risk of astronaut flatulence in a pure oxygen environment.

What the Astronauts Actually Did

Faced with a waste management system this unpleasant, astronauts developed their own coping strategies.

Many astronauts took Lomotil (diphenoxylate/atropine), an anti-diarrheal medication, before and during the mission to reduce bowel activity. Some modified their pre-flight diets to minimize residue. The result was that many astronauts went the entire mission—up to 12 days—with as few bowel movements as physically possible.

This approach had its own medical consequences. Constipation was common post-flight. Some astronauts reported significant discomfort during the mission from deliberately suppressing normal bodily functions.

The medical staff at NASA were aware of these self-imposed dietary restrictions and were concerned about them, but the alternative—requiring astronauts to use the bag system regularly—was considered worse for crew morale and operational efficiency than the health risks of temporary constipation.

Suited Operations: Even Worse

During suited operations—launch, reentry, and EVA—the fecal containment system was even more primitive. Astronauts wore a Fecal Containment Garment, which was NASA’s technical term for a diaper.

The garment was a pair of shorts made of absorbent material, designed to contain waste during periods when the crew couldn’t access the bag system. It was a contingency device, not intended for regular use, but the reality of spaceflight meant that biological needs didn’t always align with the mission timeline.

During the Apollo 11 lunar surface EVA, Buzz Aldrin’s first act on the Moon—before the famous small step—was dealing with a full urine collection device inside his suit. The details were not included in the CBS broadcast.

Why It Never Got Better During Apollo

The waste management system saw only minor improvements across the Apollo program. The basic adhesive bag remained the primary fecal collection method from Apollo 7 through Apollo 17.

Several factors prevented improvement:

Weight constraints: Any waste management system with mechanical complexity would add weight. In a program where engineers were machining the spacecraft skin to the thickness of aluminum foil to save ounces, a flush toilet was not an option.

Volume constraints: The Command Module cabin was already packed. There was no room for a dedicated waste facility. Astronauts used the bag system in the Lower Equipment Bay, with their crewmates floating nearby.

Zero gravity physics: The fundamental problem—that waste doesn’t separate from the body or fall into a container in zero gravity—has no simple solution. Earth-based plumbing relies entirely on gravity. Remove gravity and everything about waste management has to be reinvented from scratch.

Mission priority: NASA’s engineering resources were focused on getting to the Moon and back alive. The waste management system worked, in the sense that it didn’t kill anyone or compromise the mission. It was awful, but it was functional, and that was good enough for a program racing against a deadline.

The Legacy

The Space Shuttle eventually introduced a zero-gravity toilet that used airflow instead of gravity to direct waste into a collection chamber. The International Space Station has further refined the design. But even today, space waste management remains one of the most-complained-about aspects of spaceflight. NASA’s current toilet for Artemis missions cost $23 million to develop.

The Apollo waste management system is a reminder that even the most ambitious engineering programs have mundane, unglamorous problems that resist elegant solutions. NASA could navigate to the Moon using a 16-bit computer with woven memory. They could land on another world with a spacecraft made of aluminum foil. They could bring astronauts home through an atmosphere at 25,000 miles per hour.

But they could not build a decent toilet.