There was a great scene in the film The Right Stuff where Alan Shepard, America's first man in space, had been sitting in the Mercury capsule for more than four hours on the launch pad and was starting to feel some discomfort.
Shepard ate a hearty breakfast that morning, including two cups of coffee and orange juice. Nature took its course, and Shepard's bladder began signaling his brain that it was time to relieve himself.
The only problem was that NASA had never planned for an astronaut to urinate in space. It wasn't even considered because Shepard was only going on a 15-minute sub-orbital flight.
NASA told him to "hold it," and the countdown continued.
When another "hold" in the countdown occurred, Shepard, played beautifully by Scott Glen, said in a strained voice over the intercom, "Request permission to relieve bladder." It was either that or NASA would have to unscrew the hatch, which involved removing forty bolts, and take Shepard to the little boys' room.
Mission control opted to allow Shepard to "do it in his suit," which risked a short circuit, given that the docs had loaded his suit with sensors to monitor his bodily functions. So the astronaut turned off the power to his sensors and did his business.
The collection and elimination of human waste in space is no laughing matter. With four people riding the Artemis rocket to the Moon, it was critical for the astronauts’ health and mental well-being to have a working toilet.
Waste management systems at NASA have perplexed engineers for decades. The first "system" was a prophylactic that astronauts would pee into and then store until landing. John Glen's flight in Friendship 7 featured a rudimentary system that captured the urine and vented it into space.
It wasn't until the 1980s that NASA began to seriously examine the problem of waste control and management, especially in long-duration flights. The agency developed a super-absorbent garment called "MAG" that functioned like a high-tech diaper. It proved adequate for the first woman in space, Sally Ride, solving the problem of how to accommodate the female physique.
The Space Shuttle actually had a "throne-like" design that relied on air suction rather than gravity. For female astronauts, NASA developed a contoured urine collection funnel designed to be held against the body to ensure a seal, preventing liquid from escaping in microgravity.
In 2020, NASA launched the Universal Waste Management System (UWMS), which features a more compact, ergonomic, and "universal" toilet designed to be easier for female crew members to use. It was re-engineered to better accommodate female anatomy for simultaneous urination and defecation, while high-speed fans create powerful suction to ensure waste is pulled away from the body immediately. It even uses advanced chemistry to prevent the build-up of "biofilms" in the wastewater tank.
Even with advanced technology, microgravity waste management remains difficult. During the Artemis II mission, NASA encountered issues with the urine venting system becoming clogged.
"The toilet remains operational," Artemis 2 Flight Director Rick Henfling said during a press conference on Tuesday afternoon.
"The challenge that we're working through is evacuating the tank," he added. "The vent is a lot less than we were expecting, and so we're having to fall back to some other alternate means, other than the toilet."
The mission team had hypothesized that ice may be blocking the vent nozzle on Orion's exterior, Henfling explained. But that doesn't seem to be the case; the problem persists, even after heaters were engaged and Orion was tilted toward the sun to "bake away" the proposed ice.
So what's actually going on?
"The latest theory is related to some of the chemistry that goes into ensuring that the wastewater doesn't develop any biofilms," Henfling said. "And there may be something going on with a chemical reaction where there's some debris that's generated as part of that reaction, and it's getting clogged in a filter."
That theory needs to be checked out, however. The mission team likely won't get any concrete answers until they can examine Orion up close, Henfling and others stressed.
On the ill-fated Apollo 13 mission that was nearly lost after an oxygen tank exploded on the way to the Moon, astronauts were forced to store the waste in plastic bags. NASA engineers were rightly concerned that venting urine into space would change the Lunar Module's trajectory, throwing the craft off course, since they had an extremely limited amount of fuel. It only added to the misery of the astronauts who spent nearly three days in freezing cold, dark conditions.
On future space missions, astronauts will find uses for the waste. Urine is already being repurposed on the International Space Station (ISS). NASA developed the Urine Processor Assembly (UPA). This system distills urine into pure water, which is then used for drinking, food rehydration, and oxygen production. Modern systems can recover 98% of all water that astronauts bring into space by recycling both sweat and urine.
Once we set up a base on the Moon, urea, the main organic compound in urine, can act as a plasticizer. When mixed with lunar regolith (moon dust), it creates a type of "lunar concrete." Of course, solid waste can be used as fertilizer to increase crop yields.
Every ounce of human waste used or repurposed is one less ounce that has to be lifted from the surface of the Earth. The current cost for NASA has dropped from about $25,000 per pound in the Shuttle era to SpaceX's Falcon Heavy at $750-$900 per pound. Once the massive SpaceX Starship enters service and can be rapidly reused, the cost could drop to under $100 per pound.
The waste disposal problem will be solved as every other hurdle to space travel is being solved: through imagination, perseverance, and inspiration.
