Later this year, astronauts on the American module of the ISS will be able to test out the toilet before NASA puts it on crewed vehicles for deep-space missions.
The International Space Station is one of the most advanced laboratories ever made. It’s home to the coldest spot in the known universe, “organs on a chip,” a supercomputer, and quantum lasers. And later this year, it will also have the distinction of hosting the most advanced bathroom ever made. Known as the Universal Waste Management System, this high-tech porta potty was under development for six years and cost more than $23 million to build. It is scheduled to be delivered to the space station in a Northrop Grumman Cygnus cargo capsule in September.
Unlike the two bespoke versions currently on the space station, NASA’s new space toilet is designed to work with a variety of future crewed spacecraft. In the near term, it will be installed on Orion, the capsule that will carry NASA astronauts to the moon in just a few years. Melissa McKinley, who leads the NASA team working on the Universal Waste Management System, says that the toilet may also eventually be used in crewed lunar landers or in spacecraft headed to Mars. But before any of that happens, NASA is sending it to the ISS for a three-year test to make sure everything works as planned.
The new toilet is a compact white cylinder that shares many features with NASA’s previous space toilet designs. It has a funnel for suctioning pee, a removable waste compactor where astronauts drop their droppings, and a seat with a protruding lip around the small opening to help an astronaut aim. One of the biggest differences in NASA’s new toilet is that it is compact and completely self-contained, whereas the old ISS system was hidden behind the bulkhead and made repairs difficult. It also has a system built in that pretreats urine before passing it off to the space station’s life-support system to be recycled for water.
But McKinley says one of the biggest improvements was changing the design to better meet the needs of female crew members. “It’s more complex for female crew to urinate and defecate at the same time because of the placement of the urine funnel and where they have to place themselves to do defecation,” says McKinley. “There was a proximity issue, so the seat and urine funnel have both been engineered to improve the experience for female crew.”
The new version will be placed in a stall next to an existing toilet on the ISS, but the cabin wasn’t designed to host two bathrooms side by side. So early last year, the astronauts on board the space station donned their plumber hats and set to work preparing for the new laboratory lavatory. While setting up the new stall, the old space toilet sprung a leak and spilled a few liters of water before it was fixed. The toilets on the ISS have malfunctioned on several occasions, but McKinley hopes NASA’s new simpler design will help avoid these issues in the future.
Hitting the loo in microgravity may not be glamorous, but astronauts today have it a lot better than the first humans to venture into the final frontier. In the early days of human spaceflight, NASA didn’t even bother putting bathrooms on the spacecraft. During the Apollo 11 mission to the moon, the three astronauts in the command capsule peed into a condom-like sleeve that collected the urine in a bladder worn under the clothing; feces went straight into bags. NASA’s first space station, Skylab, marked the first time a toilet was integrated into a NASA spacecraft. It consisted of a hole in the wall that sucked in urine and poop and stored it in bags for analysis.
The waste collection system installed on the space shuttle was the first one that kind of resembled a toilet you might find on Earth. It had a cylindrical metal bowl equipped with fans to pull feces away from the astronauts in microgravity and a suction hose connected to a funnel for urine. Although the first shuttle missions had some problems with the toilet, “the Universal Waste Management System builds on that legacy,” says McKinley. “As we progress through space exploration, there’s an evolution of the toilet as well.”
Pooping in microgravity is always going to be a challenge, despite NASA’s attempts to make the experience as hassle-free as possible for astronauts. But Zachary Taylor, a space architect at NASA’s Johnson Space Center, has some ideas about how to make extraterrestrial bathrooms even better. In a forthcoming paper in Acta Astronautica, Taylor outlines what he calls a bathroom “manifesto” that calls for rethinking the way astronauts do their business in space.
“The bathroom is more than just a room with the toilet shoved in the corner,” says Taylor. “There’s a lot more room for innovation than most people assume.”
For starters, there’s the issue of comfort. The toilet seats in the space station’s bathrooms have such small openings that crew heading to space actually have to do target-practice as part of their training. This involves sitting on a simulated space toilet with a camera in the bowl and practicing alignment by watching, via a screen in front of them, where their butt is positioned. “It’s been a running joke that the toilet is easy to miss,” Taylor says.
Most design choices NASA makes for the space toilet are utilitarian, and the small seat is no exception. In space, everything floats in microgravity, so the toilet is designed to use air flow over the seat to whisk feces away from the astronaut into a plastic bag placed in the bowl. The small opening helps create a seal and prevents anything from escaping into the bathroom. Once it has been captured in the bag, it is stored in an airtight container for shipping back to Earth. It’s essentially the same low-tech—and giggle-worthy—solution that NASA has used since we first sent astronauts to the moon.
“The poop bags come up again and again, and it frustrates me because we’ve made so many advances elsewhere, but this topic just gets ignored,” Taylor says about space toilet design. “It makes some people uncomfortable, but I think it’s just as important for the long-term health and performance of the crew as a good cockpit design or bed.”
The small opening may be here to stay, but Taylor says there are other ways to increase astronaut comfort while they’re on the pot. For example, to maintain contact with the seat, astronauts typically have to use finger latches on either side of the bowl. But Taylor says astronauts don’t like this system much because they can’t use their hands for reading or accessing storage compartments in the bathroom. Instead, his paper proposes hands-free restraints that are more like a seatbelt or a lap restraint on a roller coaster.
Arguably a more pressing problem for long-duration missions is how different designs can affect astronaut health. The Universal Waste Management System is designed like a conventional Western toilet, where astronauts’ thighs are at a right angle to the floor. But research by an Israeli physician demonstrated that this position can put unnecessary strain on a person’s bowels. When it comes to pooping, the ideal position is a squat in which a person’s thighs are pressed against their chest. This position can help prevent hemorrhoids and anal fissures by reducing straining and help completely empty the bowels. (It’s unclear whether squatting also reduces the risks of more serious health problems like colon cancer.)
For long missions, reducing health risks, however small, is the name of the game. Changing the design for the toilet interface is a relatively straightforward way to improve an astronaut’s health. In his paper, Taylor proposes four modified designs of the Universal Waste Management System. He says his goal wasn’t to change the underlying hardware, which McKinley and her team spent years perfecting to meet the exacting requirements of future crewed space vehicles. Instead, he says, “it’s about how to add a bit more of a human-friendly interface to it.”
His designs change the toilet’s position to make it closer to the wall or floor and incorporate a new seat to enable squatting positions. Other proposed changes are to improve the sanitariness of the bathroom, such as by swapping out 90-degree corners for curved surfaces that are easier to clean. Importantly, all of these designs work with NASA’s current design. “This thing isn’t going to go anywhere,” Taylor says of the Universal Waste Management System. “It’s going to go on Orion, on the Lunar Gateway, and maybe even in a commercial lunar lander, so I had to make it work.”
For now, Taylor’s alternative bathroom designs are destined to remain on paper. NASA already delivered a Universal Waste Management System to Kennedy Space Center for integration into the Orion capsule that will carry astronauts on a journey around the moon as part of the planned Artemis-2 mission in 2023.
In the meantime, NASA is exploring other ways to improve its waste systems for future missions. For example, the agency is researching how to extract water from solid waste so it can be recycled for crewed missions. Water is a precious resource in space, and even though feces are up to 75 percent water by mass, all of it currently goes to waste. If water could be extracted from astropoop, it could allow other sources of recycled water, such as urine, to be put to use as a building material or fertilizer. NASA will be harvesting data from the test toilet on the space station as well as feedback from the crew that will inform design changes to the Universal Waste Management System. “We’re going to learn a lot from trying this thing out,” McKinley says. “We’re already thinking of ways to improve the next version.”
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