It was 8:15 AM on May 5, 1961, and astronaut Alan Bartlett Shepard Jr. was facing an unexpected crisis. Chosen to be the first American – and the second human – in history to blast into space, at 5:15 AM Shepard had been strapped into his Mercury spacecraft Freedom 7 and the hatch bolted shut behind him. Liftoff was scheduled for 7:20 AM, but a series of delays caused by cloud cover over Cape Canaveral and various technical glitches resulted in Shepard sitting atop his Redstone rocket for over three hours. Soon, an unwelcome feeling began to creep over Shepard’s body, growing worse and worse with every passing minute. At first he tried to ignore it, but eventually the feeling became so unbearable Shepard was forced radio his Capsule Communicator or CapCom: he had to urinate – badly. Mission Control was stunned. No one had even considered how Shepard was supposed answer the call of nature; after all, his suborbital mission was only supposed to last 15 minutes. It was a problem which has plagued astronauts ever since, prompting engineers to develop a variety of weird, wonderful – and sometimes disgusting – solutions. This is the story of how astronauts boldly “go” where no one has gone before.

Prior to the Space Race, little thought was given to how future astronauts would relieve themselves during missions. The first system for collecting urine during long flights was developed in 1955 for pilots of the Lockheed U2 spy plane, who, flying at altitudes in excess of 21,000 metres, had to wear partial-pressure suits in order to survive. This system took the form of an in-dwelling catheter, a small plastic tube threaded up the pilot’s urethra into their bladder which automatically siphoned urine through a hose into a collection bag. As you can imagine, this system was extremely uncomfortable and decidedly less than popular with pilots. It also ran the risk of irritating or damaging the urethra walls and causing urinary tract infections. Later, an external system was developed that used a condom-like latex sleeve that rolled over the pilot’s penis. But while significantly more comfortable than the catheter, this Urine Collection Device or UCD was not without its problems. Indeed, in a 2010 survey of U2 pilots based at Beale Air Force Base in California, 60% of respondents reported problems with their UCDs, including poor fit, leakage, and skin irritation from prolonged contact with urine.

Furthermore, due to the extreme secrecy within the CIA – which operated the U2 – external UCD technology was not shared with NASA. And while in 1957 a group of British inventors patented a similar device for use with pressure suits “or equipment whose position or body harness makes normal urination highly inconvenient or impossible” which diverted urine into a bag of absorbent material, this design does not appear to have reached NASA planners either.

Following the launch of Project Mercury – the first American manned space programme – in 1958, the United States Air Force sponsored a study on human waste collection in a spacecraft. For the short-duration Mercury missions then being planned, faecal collection was not deemed necessary, though urine collection would likely be required. The study examined contemporary urine collection devices then on the market and concluded that the designs in use aboard military aircraft were inadequate due to excessive leakage – a problem that would only be exacerbated by microgravity. Instead, the final report recommended the use of commercial UCDs used in hospitals on bedridden male patients, which formed a tight seal around the penis and featured a one-way valve to preventback flow. Strangely, however, NASA seemingly ignored this and similar studies, and both the original Mercury Seven astronauts’ training and the testing of the Mercury Spacecraft and the Navy Mk.IV space suit were conducted entirely without any form of UCD. Indeed, when a 12-year-old Pennsylvania schoolgirl wrote to NASA in February 1961 to ask:

Dear Sir,

In our science class we were talking about the first man that would go into space and we would like to know where they go to the toilet when there [sic] up in space and there’s no gravity.

Yours truly,

Brenda Kemmerer

…Dr. Freeman H. Quimby of NASA’s Office of Life Science Programs replied that “…the first space man is not expected to have ‘to go’”. As the first spaceflights would last only 15 minutes, astronauts were simply expected to “hold it” until brought aboard the recovery ship after splashdown.

…which brings us back to the morning of May 5, 1961, and Alan Shepard’s awkward pre-flight dilemma. While NASA records indicate that a urine collection container was installed near the capsule’s entrance hatch, this would have been impossible for Shepard to use, being firmly strapped into his form-fitting flight couch. And letting Shepard out to use the regular facilities would have required the pad crew to laboriously unfasten the 70 bolts holding the hatch shut, further delaying the launch. Unable to resist the urge any longer, Shepard requested permission to urinate in his spacesuit. At first Mission Control refused, fearing that the urine would short out the biosensors monitoring Shepard’s vital signs. But when Shepard suggested they simply switch the sensors off, they relented, and a very relieved Shepard proceeded to – well, relieve – himself. Due to Shepard’s supine, legs-up position, the urine pooled in the small of his back and soaked into his one-piece wool undergarment, where the cool pure oxygen flowing through the spacesuit quickly dried it out. The crisis averted, the countdown resumed, and at 9:34 AM Shepard blasted off into the wild blue yonder, reaching an altitude of 187.5 kilometres before reentering the atmosphere and splashing down in the Atlantic Ocean 487 kilometres east of Cape Canaveral. Though less impressive than Soviet cosmonaut Yuri Gagarin’s historic orbit of the earth less than a month before, the flight of Mercury Redstone 3 finally put the United States firmly in the Space Race – and for more on the – shall we say less than stellar – early days of the U.S. space program, please check out our previous video ‘Kaputnik’: America’s Largely Forgotten Disastrous First Attempt to Launch a Satellite.

Alan Shepard’s embarrassing experience as an incontinent ballistic missile prompted NASA to pursue a practical UCD design in time for the next Mercury mission – the July 21, 1961 Mercury-Redstone 4 flight of astronaut Virgil I. “Gus” Grissom. A popular legend holds that Dolores B. “Dee” O’Hara, nurse to the Mercury Seven astronauts, cobbled together the first UCD on the eve of Grissom’s flight using a condom and a woman’s girdle. In reality, Grissom wore two pairs of rubber incontinence pants such that the urine would collect between the two layers. He was also denied his morning coffee – a known diuretic. In the event, Grissom never ended up needing to relieve himself, which is perhaps unsurprising given the sphincter-tightening turn his mission took shortly after splashdown – and for more on how America’s second astronaut was nearly lost at sea, please check out our previous video Forgotten History: NASA and the Sinking Spacecraft.

Meanwhile, NASA assigned James McBarron to oversee efforts at B.F. Goodrich – the company that produced the Mercury astronauts’ Navy Mk.IV spacesuits – to develop a standardized UCD for subsequent spaceflights. The company was unable to produce a satisfactorily leak-proof system, leading McBarron, along with Al Rochford and Joe Schmitt of NASA’s Manned Spaceflight Center Suit Laboratory, to tackle the problem themselves. McBarron purchased condoms from various commercial manufacturers and tested them for fit and durability until he found the ideal brand, then worked with that manufacturer to develop the finalized urine-collection sleeve. The final UCD consisted of an elasticized belt worn beneath the astronaut’s spacesuit, to which was attached the latex sleeve, a short rubber hose, a one way valve to prevent flow reversal, a clamp to seal off the system after splashdown, and a flat polyethylene collection bag. The whole assembly was held in place by a set of tight-fitting undergarment.

Another popular myth associated with the early American space program is that NASA had to change the size classifications on its UCDs in order to accommodate the astronaut’s legendary egos. This story seems to have originated with engineer Donald Retake – nicknamed “Dr. Flush” due to his extensive work on astronaut waste-collection systems – who stated in the 2008 Science Channel documentary series Moon Machines:

“Inside the urine collection assembly, which we call the pee pouch, is a one liter bag. And the attachment to the body was a condom with a hose on the end of it which allowed the urine to flow freely into the bag. The condoms initially came in three different sizes: small, medium and large. But few astronauts, whatever their real dimensions, refused to accept that they were anything but large. We changed the names to large, gigantic, and humongous.”

Apollo 11 astronaut Michael Collins repeated this anecdote in his 1974 autobiography Carrying the Fire: an Astronaut’s Journeys, writing that:

“…Then it’s time to don a triangular yellow plastic urine bag by inserting the penis into a rubber receiver built into one corner of it. There are three sizes of receivers (small, medium, large), which are always referred to in more heroic terms: extra large, immense, and unbelievable.”

In reality, this sizing system seems to have been merely an informal joke among the astronauts rather than a psychological trick played by NASA. Indeed, whatever their preconceptions and insecurities, the astronauts quickly learned from experience what size of sleeve to use, as Apollo 9 astronaut Russell “Rusty” Schweickart later recalled:

“There’s always the possibility that in maneuvering around in a suit you can end up pulling off the condom, and there’s always — we have three sizes you know, small, medium and large — in diameter, and there’s always this little ego thing about which one you do pick. Of course the smart guy picks the right size, because it’s very important. But what happens is, if you get too small a size it effectively pinches off the flow and you just turn yellow because you can’t go; and if, on the other hand you’ve got an ego problem and you decide on a large when you should have a medium, what happens is you take your first leak and you end up with half of the urine outside the bag on you. And that’s the last time you make that mistake. So it’s a cute little trick there.”

Whatever the case, McBarron’s UCD was first used during the February 20, 1962 Mercury-Atlas 6 mission, during which astronaut John Glenn became the first American to orbit the earth. Over the course of his three orbits, Glenn used his UCD once, depositing 756 millilitres of urine into the collection bag. Remarkably, this is over 30% greater than the capacity of the average male bladder – a result of the strange effects of microgravity on human physiology. Normally, gravity pulls urine towards the bottom of the bladder, causing the walls to gradually expand. When the bladder is approximately two-thirds full, nerves begin to register this expansion and signal the body that it is time to urinate. In microgravity, however, urine tends to collect in a sphere, and does not begin to press on the walls until the bladder is already far beyond its regular capacity. While overshadowed by his other achievements, in its own modest way John Glenn’s orbital whiz was a milestone in space systems engineering – which is probably why his UCD has been on public display at the National Air & Space Museum in Washington, D.C. since 1970.

Though sometimes prone to leakage if improperly sized or fitted, James McBarron’s UCD design became the NASA standard throughout the Mercury, Gemini, and Apollo programs. During flights to and from the moon, Apollo astronauts could connect their UCDs via a hose to a Urine Transfer System or UTS, which collected the urine in an onboard tank. Most of this urine was then vented overboard, but some was retained for analysis by flight surgeons after the mission. And when the astronauts were working on the lunar surface, the urine drained into a polyethylene bag worn under their spacesuits. Amusingly, while only second to step off the Lunar Module, Apollo 11 astronaut Edwin “Buzz” Aldrin did achieve a space first of his own, becoming the first person to relieve themselves on the lunar service. The act, performed just before Aldrin stepped off the Lunar Module ladder, remains a minor a source of pride for the astronaut, with Aldrin later stating:

“Everyone has their firsts on the moon, and that one hasn’t been disputed by anybody.”

Unfortunately, however, the experience was somewhat less tidy than Aldrin might have hoped. Mission commander Neil Armstrong’s landing was so soft that the Lunar Module’s legs didn’t compress as much as expected. So when Aldrin jumped off the ladder onto the lunar surface, he fell farther than anticipated and the resulting jolt damaged his UCD, causing urine to collect not in the proper bag, but rather in one of Aldrin’s spacesuit boots. That’s right: throughout the mission’s historic 2 hour, 31 minute lunar EVA, Buzz Aldrin was walking around with urine sloshing around in his boot. We’ve all been there, Buzz…

The UCD remained in use into the early Space Shuttle program, when it was replaced by the Disposable Absorption Containment Trunk or DACT – effectively an advanced set of adult diapers. The DACT was developed in response to NASA’s 1978 opening of the astronaut corps to female candidates, whose anatomy was incompatible with the original UCD. They were first flown in space on April 4, 1983 by the all-male crew of STS-6, the first mission of the Space Shuttle Challenger, while two months later on June 18 they were worn by the United States’ first female astronaut, Sally Ride, during the STS-7 mission. However, NASA quickly realized that the custom-fabricated DACTs were not economical, and that it would be far more cost-effective to purchase commercial off-the-shelf adult diapers. Known as Maximum Absorbency Garments or MAGs, these units replaced the DACT starting in 1988 and contain enough sodium polyacrylate material to absorb two litres of urine or other bodily fluids. They are still worn by American astronauts under their launch entry suits during liftoff and reentry and under their Extravehicular Mobility Units or EMUs during extravehicular activities or “spacewalks” – and for more about the surprising engineering challenges of working out in the hostile vacuum of space, please check out our previous video Touching the Void: the Story of the Space Jet Pack.

At this point in the video, you’ve likely noticed that we’ve left out an important part of the waste-disposal equation. Namely: #2. Yes, that #2. Even more than urine collection, early NASA planners and engineers were loath even to consider the problem of solid waste management, and simply chose to sidestep the issue entirely. After all, early Mercury missions weren’t supposed to last more than a day – and for more on the incredible badassery of the last and longest Mercury mission, please check out our previous video “I’ll do it Myself” – the Greatest Feat of Piloting in Space. However, in order to avoid accidents, in the days leading up to a mission astronauts were fed a “low residue” diet high in protein and low in fibre – for example steak and eggs, which has since become the traditional pre-flight breakfast for American astronauts. This diet also minimizes the production of intestinal gases, which in the reduced atmospheric pressure of a spacecraft cabin can expand and produce severe pain. Even today, Russian cosmonauts follow a similar practice. Though the Soyuz spacecraft typically takes only a few hours to reach the International Space Station, depending on orbital maneuvers crews can sometimes spend several days in orbit before docking. And while the Soyuz does feature a rudimentary space toilet – more on that later – cosmonauts don’t like to use it, and will often combine their low-residue diet with a pre-flight enema to completely clean out their bowels.

But while this strategy worked well enough for Mercury, as NASA transitioned over to the longer-duration Gemini and Apollo flights, the problem of collecting #2 could no longer be ignored. But the solution they came up with, the Fecal Collection Assembly or FCA, would prove to be one of the most reviled pieces of hardware in the history of spaceflight. Manufactured by the Whirlpool Corporation, the FCA consisted of a small clear plastic bag with an adhesive gasket intended to seal the opening to the astronaut’s bare buttocks. Ordinarily, back on earth bowel movements are separated from the anus by good old gravity, but in the microgravity of space, this does not occur. The FCA thus featured a small pouch or cot in its side wall into which the astronaut could insert their finger to help dislodge stubborn turds. Lovely. Once the deed was done, the FCA came packaged with sheets of toilet paper and wet wipes with which the astronaut could clean themselves, which were disposed of inside the bag along with the astronaut’s…leavings. But if this whole process already sounds completely undignified – especially if performed in front of others in the cramped confines of a spacecraft – brace yourselves, because it gets even worse. Unlike urine, there was no mechanism to jettison the filled FCAs, which instead had to be stored onboard. But without further treatment, the bacteria-riddled droppings would quickly ferment and produce gases like methane, causing the bags to inflate and possibly burst – resulting in the most literal manifestation of the expression “the shit hitting the fan.” Each FCA thus came packaged with a packet of germicidal liquid, which the astronaut was supposed to insert into the bag before sealing it. They would burst the packet by squeezing it, then thoroughly knead the germicide into the poop to ensure that all the gas-generating bacteria were killed.

As you can imagine, astronauts hated using the FCAs, and tried to avoid defecation by any means possible, such as simply holding it in or eating only half of their assigned meals – and to learn more about how astronauts stay properly fed and hydrated in space, please check out our previous video What’s Up With Space Food? And really, you can’t blame them. As NASA’s own officials history states:

“The fecal collection system presented am even more distasteful set of problems. The collection process required a great dead of skill to preclude escape of feces from the collection bag and consequent soiling of the crew, their clothing, or cabin surfaces. The fecal collection process was, moreover, extremely time consuming because of the level of difficulty involved with use of the system. An Apollo 7 astronaut estimated the time required to correctly accomplish the process at 45 minutes. Good placement of fecal bags was difficult to attain; this was further complicated by the fact that the flap at the back of the constant wear garment created an opening that was too small for easy placement of the bags.”

Furthermore, improper use of the FCA could lead to disgusting situations, as the crew of Apollo 10 – the dress rehearsal for the Apollo 11 lunar landing – discovered in May 1969:

[Lunar Module Pilot Eugene] Cernan: “Where did that come from?”

[Commander Tom] Stafford: “Get me a napkin quick. There’s a turd floating through the air.”

[Command Module Pilot John] 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” (laughter)

Cernan: “Here’s another goddam turd. What’s the matter with you guys? Here, give me a —”

(laughter from Young and Stafford)

Stafford: “It was just floating around?”

Cernan: “Yes.”

Stafford (laughing): “Mine was stickier than that.”

Young: “Mine was too. It hit that bag —”

Cernan: “I don’t know whose that is. I can neither claim it nor disclaim it (laughter).”

Young: “What the hell is going on here?”

Just who was responsible for this close encounter of the turd kind remains a mystery to this day, though we did a deep dive investigation on it and our theory of who done it in our video To Boldly Go Where No Fecal Matter Has Gone Before if you care to watch after this video.

And even if waste remained safely inside the bags, with space inside the Gemini and Apollo capsules at a premium, finding storage for used bags and other trash quickly became a challenge. This lack of adequate waste disposal led Gemini V astronauts Leroy “Gordon” Cooper and Charles “Pete” Conrad to dub their August 1965 mission “eight days in a garbage can.” Gemini VII astronauts Frank Borman and Jim Lovell fared even worse, orbiting the earth for 14 days in a space no larger than the front seat of a Volkswagen Beetle with no good way of disposing of their trash. Yet despite their enduring notoriety, FCAs remain in use to this day as a backup in case the space toilets aboard the ISS fail.

By the end of the 1960s, it became clear that if astronauts were to spend long periods of time in space, they needed a more comfortable – and dignified – means of answering nature’s call. The Soviets were the first to fly a proper space toilet, which has been standard equipment on the Soyuz spacecraft since its maiden flight in 1967 – and to learn more about this flight’s tragic ending, please check out our previous video The Most Disastrous Space Mission Ever Executed. This installation was made possible by the Soyuz’s large elliptical orbital module, which sits above the bell-shaped descent module and is jettisoned just before reentry. Like nearly all space toilets developed since, the Soyuz facilities consist of two main parts: a suction hose with a funnel for collecting urine, which is vented into a chamber lined with absorbent foam; and a commode which uses a fan and airflow to suck faeces into plastic bags, which are then sealed and stored onboard.

Meanwhile, the first American space toilet was flown aboard the Skylab space station, which hosted three crews between May 1973 and February 1974. Like the Soyuz facilities, the Skylab toilet – designed by the Fairchild Republic Corporation – used a fan to suck faeces into a plastic bag. The astronauts then used an electric heater and vacuum from outside to dry the excrement, preventing it from fermenting and fouling the space station air. A separate suction hose was used to collect urine. Adding to the sanitary arrangements, Skylab was unique in being the first and last spacecraft in history to feature a microgravity shower. This was enclosed in a telescoping cylindrical curtain and featured foot restraints, a water sprayer nozzle on a flexible hose, and a vacuum system for carrying away wastewater. Astronauts were provided with 420 terrycloth towels, colour-coded to each astronaut. Today, astronauts aboard the ISS keep themselves clean using wet wipes, no-rinse shampoo, and similar products.

For the Space Transport System or STS program – better known as the Space Shuttle – NASA developed a new, more sophisticated space toilet known as the Waste Collection System or WCS. Like earlier systems, the WCS used a vacuum hose to collect urine, though it featured two different detachable heads for male and female astronauts. The male head was funnel-shaped, while the female head was elliptical, with small holes around the rim to allow airflow and prevent excessive suction. The collected urine was then jettisoned overboard. For #2, the WCS featured a special seat with foot stirrups, handholds, a seatbelt, and roller-coaster-esque thigh restraints to hold the astronaut in place. Early versions of the design featured a rapidly-spinning “slinger/shredder” mechanism to break up the waste and direct it onto the walls of the collection tank; however, astronauts understandably objected to having what amounted to a giant garbage disposal so close to their private parts, so the design was changed to use a suction fan as in earlier space toilets. This fan distributed the waste onto the walls of a cylindrical collection tank; after they were finished their business, astronauts would open a valve to expose the tank to the vacuum of space, flash-freeze drying the contents and preventing odours from forming. Toilet paper, wipes, and other hygiene products were placed in sealed plastic bags and disposed of in a separate compartment.

To ensure a tight seal and minimize leakage, the hole in the WCS seat was only 100 millimetres or 4 inches in diameter – much smaller than on a conventional toilet. Precise positioning of the user’s body was therefore essential, and prior to flight astronauts underwent extensive training on a space toilet simulator – no, really – at NASA’s Johnson Space Centre in Houston, Texas. This simulator featured lights to indicate to the trainee if they were in the proper position, as well as an internal camera to allow an instructor to check the trainee’s alignment (and you thought your work onboarding was awkward…). As every body is different, each astronaut quickly learned what position worked best for them. As veteran American astronaut Mike Massimo explains:

“I think of Peter Fonda in Easy Rider. That’s the right position for me.”

Adding to the indignity, the genuine article aboard the Space Shuttle itself featured a microphone so flight surgeons back on earth could monitor the astronauts’ bowel sounds and gauge their overall digestive health. This, in turn, led to the creation of what has to be the least glamorous job in the history of space exploration. In the early days of the Shuttle program, NASA was often contracted by the U.S. military to deploy top-secret surveillance satellites from the orbiter’s cargo bay. Military intelligence worried that the microphone on the WCS might accidentally pick up conversations about the classified payload, and so some unfortunate officer was tasked with listening to days of astronaut bowel sounds to ensure that no national secrets leaked out. Now your boring day job doesn’t sound so bad, does it? The only saving grace is that while the flight surgeon could hear an astronauts’ every sound, their fellow crewmates couldn’t. Despite the WCS being separated from the rest of the cabin by only a thin curtain, the sound of various pumps and other onboard systems was so loud that the astronauts could use the facilities in relative sonic privacy.

But while far superior to the hated Apollo FCA bags, the WCS was not without its faults, and over the Space Shuttle’s 30-year service life the system suffered a number of major malfunctions. During STS-3, the third shuttle flight in March 1982, the WCS failed on its first use, forcing the two-man crew, Commander Jack Lousma and Pilot C. Gordon Fullerton, to use FCA bags for the rest of the eight-day flight. On September 3, 1984 during STS-41D, the maiden flight of the Space Shuttle Discovery, a malfunction in the liquid disposal system led to the formation of a 60 centimetre or two foot long frozen “pee-sicle” on the orbiter’s hull. Thankfully, the following day mission commander Henry Hartsfield Jr. managed to break off the obstruction using the Shuttle’s Remote Manipulator Arm – AKA the Canadarm. The WCS also had a more fundamental design flaw: sometimes bits of freeze-dried faeces would flake off the tank walls and float out through the bowl into the cabin, fouling the air – ew.

But the most serious malfunction of the WCS occurred on November 23, 1989 – Thanksgiving Day – during STS-33, Discovery’s ninth flight. Early that morning, mission Commander Fred Gregory awoke to use the facilities. Everything went well at first, but when Gregory made to seal off and depressurize the collection tank, the valve connecting the tank to the outside opened but the slider valve connecting the tank to the bowl failed to close. Suddenly, the cabin – and Gregory’s backside – were exposed to the vacuum of space, suctioning him fast to his seat. To make matters worse, the vent for topping up the Shuttle’s atmosphere with fresh oxygen was located right above the WCS. So not only was Gregory stuck in place, the Shuttle’s precious air roaring past his most delicate bits, but he was also being doused with a shower of ice-cold, recently liquefied oxygen. Immediately the cabin depressurization warning klaxon blared, and Gregory’s crewmates rushed over to the rescue. Mission specialist Story Musgrave managed to wrestle the stuck slider valve shut, freeing a grateful – if very chilled – Gregory, but now the crew if STS-33 faced an unpleasant dilemma: if they could not fix the troublesome valve, they would be forced to use the dreaded FCA bags for the rest of the five-day mission. Unsurprisingly, the crew overwhelmingly voted to scrub the mission and return to earth early rather than face this option. However, this would have required the Shuttle to come down at one of its alternate landing sites in Africa, as it was off-track for a conventional landing at the Kennedy Space Centre.

Thankfully, after consulting with Mission Control, the astronauts determined that by ripping off the front cover of the WCS and clamping a pair of vise-grip pliers to the slider valve lever, they could continue to safely use their cosmic commode – proving that Clint Eastwood was right in Gran Torino: you can fix anything with duct tape, WD-40, and vise grips. Their scatological scare averted, the crew tucked in to their Thanksgiving dinner of turkey, potatoes, and broccoli, and enjoyed a largely uneventful mission.

In the year 2000, NASA introduced a new toilet for use aboard the International Space Station, which had just begun construction two years before. Though broadly similar to the Space Shuttle WCS, the ISS toilets use not a single collection tank, but rather 20 litre or 5 gallon micro-perforated plastic bags held in an aluminium container. The microperforations allow air but not liquids or solids to flow through the plastic, allowing the toilet fan to pull waste to the bottom of the bag. Once full, the containers are sealed and, along with the rest of the space station’s trash, loaded aboard unmanned Grumman Cygnus or Russian Progress supply spacecraft to burn up in the atmosphere. So now you know: if you look up into the night sky and see a particularly bright shooting star, there’s a good chance it might be burning astronaut poop.

Yet despite numerous improvements to the design, using the ISS toilet is still far from a pleasant experience, with most astronauts listing going to the bathroom as their least favourite part of spaceflight. As veteran astronaut Peggy Whitson – who holds the NASA record for most time spent in space at 665 days – explains:

“After [the collection bag] starts getting full, you have to put a rubber glove on and pack it down.”

Meanwhile, urine is collected much as it has been for decades: using a separate vacuum hose with male and female adaptors. However, since water is such a precious commodity and very heavy and bulky to launch into orbit, urine is not jettisoned overboard as in previous systems but rather recycled into potable drinking water via a sophisticated reclamation system called the Water Processor Assembly or WPA, which uses a series of micofilters and catalyst beds to remove and neutralize contaminants. As NASA astronaut Jessica Muir explains.:

“We recycle about 90% of all water-based liquids on the space station, including urine and sweat. What we try to do aboard the space station is mimic elements of Earth’s natural water cycle to reclaim water from the air. And when it comes to our urine on ISS, today’s coffee is tomorrow’s coffee!”

As in previous space programmes, some of the astronauts’ waste is stored and returned to earth for analysis by flight surgeons. Urine is first collected in plastic bags very similar to the Urine Collection Devices used by the Mercury, Gemini, and Apollo astronauts. Syringes are then used to extract samples, which are stored in a special compartment called the Minus Eighty Degree Laboratory Freezer for ISS (MELFI) until they can be returned to earth by a Soyuz or Dragon spacecraft.

As of this recording, solid waste is not processed to extract its moisture, though NASA is working on it. In 2021, the agency also sent a Brine Processor unit to the ISS to reclaim the remaining water that can’t be processed by the WPA. The goal is to achieve at least 98% reclamation before sending the first humans to Mars. So good news for all you Dune fans out there: real-life stillsuits may be just around the corner!

Currently, there are three toilets aboard the ISS, located in the Zvezda, Nauka, and Tranquility modules. Like the earlier Shuttle WCS, these toilets have a less-than-perfect track record, with the most serious failure occurring on May 21, 2008 when the pump for the liquid waste collection system broke. At the time, there was only one toilet aboard the ISS, forcing the astronauts to use bags or the toilet aboard the attached Soyuz spacecraft for urine collection. The solid waste system remained unaffected. Thankfully, the launch of STS-124 was scheduled for launch just 10 days later, so a replacement pump was overnighted from Russia to the Kennedy Space Centre in the diplomatic pouch and successfully delivered to the ISS on June 2. It is estimated that the three toilets aboard the ISS suffer some kind of breakdown – thankfully almost always minor – around once every month.

But with NASA preparing to send astronauts back to the moon and eventually to Mars, even the relatively advanced toilets aboard the ISS are no longer adequate. Consequently, in 2018 NASA introduced the next generation of space waste disposal: the Universal Waste Management System or UWMS. Costing $23 million to develop, the UWMS is 40% lighter, 65% more compact, and significantly more energy-efficient than the existing ISS toilets, allowing it to be more easily integrated into the Orion capsules slated to travel to the moon on the upcoming Artemis missions. When installed aboard the ISS or Mars-bound spacecraft, the UWMS will connect to onboard water-reclamation systems, while on shorter duration missions like Artemis the waste will simply be stored in a tank for later disposal. UWMS is also designed for greater comfort and ergonomics, with a tilted, form-fitting seat and an elongated, integrated funnel that allows astronauts to urinate and defecate at the same time. Greater care was also taken to make the new toilet convenient for both men and women to use.

But while the UWMS represents the current state of the art of space toilet design, one major spaceflight problem remains unsolved: how to adequately manage waste collection in a spacesuit. Currently, this is handled through the use of Maximum Absorbency Garments – AKA adult diapers – but this is only adequate for current EVAs, which typically last only a few hours. Longer-duration EVAs such as those astronauts might encounter on future missions to the Moon or Mars are a completely different animal. Collection of urine is fairly straightforward, but for men only. The specifics of female anatomy, including the shape of the genital region, the presence of pubic hair, and the realities of menstruation, greatly complicate the process. While some of these problems could be mitigated by, for example, having female astronauts shave off their pubic hair and go on birth control to regulate their menstrual cycles, this is beyond what NASA is willing to ask of its astronauts. Instead, the agency is seeking an entirely hardware-based solution. For example, in 1981 NASA patented a female urine collection device with a vaginal insert to prevent stray urine droplets or particles of faeces from drifting into the vagina and causing infections. However, such a system has not yet been successfully integrated into any practical spacesuit.

The problem of solid waste disposal is even more vexing, as containment is far more difficult to achieve and fecal matter is far more difficult to handle automatically than liquid waste. Consequently, in 2016 NASA launched the wonderfully-named Space Poop Challenge, which offered $15,000 to any inventor who could come up with a practical spacesuit waste management system. The top prize was clinched by flight surgeon and family physician Dr. Thatcher Cardon, who developed his prototypes on evenings and weekends with the help of his wife and kids. Cardon’s system features a small access port integrated into the crotch of the spacesuit, to which various bags and hoses can be attached to remove solid and liquid waste. According to Cardon, the port could also be used to perform emergency abdominal surgery and other procedures. But while innovative, the system is nowhere near ready for actual use in space, and as of this recording the problem of long-term waste management in a spacesuit has not yet been solved. But with NASA working tirelessly on the problem, we can all rest assured that when the first astronaut takes the first dump on the planet Mars, they will be aided by the very best technology humanity can concoct.

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