Canada Aviation and Space Museum
3 things you should know about pooping in space, the science behind the colour of your poop, and how our poop helps grow our crops
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May 14, 2024
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Canada Science and Technology Museum
Canada Agriculture and Food Museum
Meet Renée-Claude Goulet, Michelle Campbell Mekarski, and Cassandra Marion.
They are Ingenium’s science advisors, providing expert scientific advice on key subjects relating to the Canada Agriculture and Food Museum, the Canada Science and Technology Museum, and the Canada Aviation and Space Museum. In this colourful monthly blog series, Ingenium’s science advisors offer up three quirky nuggets related to their areas of expertise. In this May edition, they will tell us about poop.
People often forget that every single one of us is universally and biologically dependent on poop.
Poop is tremendously important. It is one of several ways that our bodies get rid of the stuff that we don’t need. It is also an important indicator of health, a potential resource, and it tells some interesting stories about our culture and history. In May 2024, the Canada Science and Technology Museum welcomes the exhibition Oh Crap! Rethinking human waste. In this month’s #3Things, we invite you to flush away your misconceptions, and explore some of the science of poop.
The Surprising Saga of Poop in Space
As far as space challenges go, human waste management can be an especially sticky one. Lack of human waste containment can not only make a mess but can contaminate the air, and enter through the eyes, nose, ears, mouth, and cuts in the skin which can lead to illness or infection.
Initially, early human spaceflights were designed for brief durations, with little consideration given to the necessity of bodily functions like urination and defecation. Yuri Gagarin, the first person in space, managed to endure until his return to Earth without issue. However, Alan Shepard, the second human in space, faced a different challenge. Delays on the launchpad of the Mercury Redstone 3 forced him to urinate in his suit, resulting in a malfunction of his electronic biosensors. This incident prompted conversations about the need for solutions and innovative approaches to astronaut waste management in future missions.
As space exploration advanced, missions became longer and more complex. Through the early years of spaceflight, astronauts tested out belt accessories such as latex roll-on cuffs with a valve and baggie, toilet seats with straps, and adult diapers (a.k.a. maximum absorbency garments). During Gemini and Apollo missions, the human waste management plan consisted of astronauts taping a plastic bag to their buttocks to defecate, then they’d mix in a bactericide. On the Apollo 10 mission, this poorly conceived method resulted in several incidents of feces flying free in the capsule. Astronaut Tom Stafford was recorded saying to his crewmates, “Oh, who did it?” and “There’s a turd floating through the air.” To this day, they have yet to determine which of the three astronauts was responsible. During the Apollo program, fecal bags were kept in a waste compartment and brought back to Earth for disposal or left on the surface of the Moon. NASA kept a log of all poops on the Apollo missions. Six Apollo landings left 96 bags of waste on the surface of the Moon! Though this was not an environmentally friendly form of disposal, it does provide an unexpected practical experiment. What are the effects of 50 years of solar radiation on microbe-rich excrement? Scientists are hoping to find out.
Photo Credit
Canadian Astronaut David Saint-Jacques doing some space plumbing on the International Space Station’s toilet, otherwise known as the Waste and Hygiene Compartment. Someone’s got to do it.
Presently, astronauts are equipped with maximum absorbency garments, or their equivalent, during critical mission phases such as launches, landings, and spacewalks lasting between five to eight hours. The inaugural space toilet was introduced aboard the Skylab orbital platform in 1973, featuring a rudimentary design comprising a wall-mounted aperture, fan, and collection bag. Waste, particularly feces, necessitated vacuum drying through heat. The Shuttle era brought about women astronauts and a new set of anatomical requirements. NASA created the disposable absorption containment trunk for spacewalks. The trunks look like a cross between a diaper and hockey shorts. Toilets on the International Space Station (ISS) are similar to Skylab, with the collection of urine and feces being separate. These facilities utilize a tube-and-funnel setup for urination and a seat over a receptacle lined with a baggie for solid waste, both linked to a suction fan ensuring proper waste disposal. A Urine Processor Assembly connected to the toilet on the ISS is able to recycle and convert 75 to 80 percent of the astronauts’ urine into potable water. Solid waste is stored for disposal and is incinerated upon re-entry aboard a cargo ship.
Looking ahead, the ISS has recently installed an upgraded toilet system known as the Universal Waste Management System (UWMS). Designed to accommodate both men and women more comfortably while also increasing overall capacity on the station, the UWMS serves as a testing ground for refining technologies. This preparation is crucial for the upcoming Artemis missions that will require human waste management facilities on board the Orion spacecraft, the Lunar Gateway space station that will orbit the Moon, and to support future waste management needs and potential uses on the lunar surface. As demonstrated in the film "The Martian," waste products can have practical applications such as fertilizing crops and providing insights into an astronaut's health and diet. The future of space toilets will be flushed with innovation.
Go Further
Universal Waste Management System
By Cassandra Marion
Brown is best: the science behind the colour of poop
Photo Credit
The iconic poop-brown colour is the result of a sophisticated interplay within your body – and is one sign of a healthy gut.
Have you ever flushed a toilet, changed a diaper, or tidied up after your furry friend and thought:
“Hmm, I wonder why poop is brown?”
Despite its unpleasant reputation, the colour of feces offers fascinating insights into the biochemical wizardry of our digestive system. From the moment food enters our bodies to its eventual exit, a complex interplay of food, enzymes, hormones, and gut bacteria culminates in the distinctive hue we commonly associate with waste.
It may surprise you that the color of your poop has more to do with your blood than the food you eat. Your red blood cells live for about 120 days, and when they reach the end of their lifespan, your liver and spleen break down the cells and recycle their components.
Hemoglobin is a protein responsible for carrying oxygen in healthy, active red blood cells. When hemoglobin gets recycled, it gets broken down into a substance called bilirubin, which is yellowish in color. The bilirubin gets transported to the liver, where it is further processed into bile, which is yellowish-green because of all the bilirubin in it.
Your liver secretes bile into the small intestine, where it performs the critical role of digesting fats. At this point in your digestive journey, your feces are yellowish-green in color because of all the bilirubin they contain.
As your feces continue to travel through your digestive system, the bilirubin gets broken down by your gut bacteria – a community of microscopic helpers that live in your intestines and help you absorb nutrients while decomposing waste. Thanks to your gut bacteria, the bilirubin breaks down, reacts with oxygen, and transforms into stercobilin – a brown pigment that gives your poop its characteristic shade.
Go further: what do other colours mean?
Brown is best, but various foods, food colourings, medications, and medical conditions can also affect the colour of your poop. When in doubt, always consult your medical provider.
Green: If your poop is green, it usually means that it went through your digestive system too fast for your gut bacteria to digest the bilirubin. You may see this shade if you have food poisoning, after taking a laxative or antibiotics, or during a stomach bug that causes poop to move through your intestines quickly. Leafy, green vegetables or other green foods with lots of chlorophyll can also stain your poop green.
Yellow: A yellow hue can indicate a high concentration of bilirubin (rather than bile). Without bile to break down fat in your intestines, your poop would have a high fat content which would add to the yellow tinge. This colour is common in infants whose livers are still maturing, and are not able to efficiently process bilirubin yet. Consuming lots of beta-carotene, a pigment found in yellow and orange fruits and vegetables, can also cause a yellowish color.
Black: Consuming certain medications (like iron pills), or dark colored foods like licorice, blueberries, or blackberries can result in black poop. However, it can also signify bleeding in your upper digestive tract since blood that is digested (rather than processed through the spleen and liver) turns black.
Red: While certain foods like beets or cranberries can cause a reddish tinge to your poop, red may also indicate the presence of blood from your lower digestive tract.
Grey or off-white: Poop that contains little to no bile will appear very pale. This may indicate a problem where the flow of bile into your intestines is obstructed.
Disclaimer: This article is for educational purposes only and should not be regarded as medical advice or replace the advice of your physician.
By Michelle Campbell Mekarski
No waste in nature: our poop helps grow our crops
Farmers can use composted animal manure to fertilize their fields, but did you know that your food could also have been grown with a small dose of human poop? Few of us really stop to think about the next destination of our excrement after the wastewater facility or the septic tank. But what goes in – food – must come out – poop – and for a very long time people tapped into this to help grow their food. Why? Because the best fertilizer is the one available consistently, for free, near the farm, and poop is all of those things.
Our bodies don't use all the nutrients in food; there are always some left over after digestion. Poop contains the three major nutrients needed for plant growth – nitrogen, phosphorous and potassium, as well as more minor nutrients like magnesium and selenium. Farmers usually supply these nutrients to plants through the use of fertilizers. Our poop also contains all the undigestible-to-us parts of food such as plant fibre, making it very rich in carbon. This element is an essential component to make soils spongy and function well. With proper care, poop can, and is, used to replace other fertilizers, and to enrich soil.
Photo Credit
Biosolids are usually injected into the soil rather than being spread on top to reduce environmental impact of using this fertilizer.
With the introduction of improved sanitation and wastewater treatment in many countries, the use of human excrement in agriculture has become less widespread. One of the reasons is improved knowledge about the role of bodily waste in transmission of disease, and environmental pollution. We are right to want to be careful about what we do with our poop. It can contain a whole slew of disease-causing agents: bacteria, viruses, protozoa, and parasitic worm eggs. Still today, many diseases spread due to poor or lacking sanitation. And let's not forget that our medicines and hormonal treatments leave residues in our poop. Biosolids from wastewater treatment facilities can also contain heavy metals and environmental pollutants from sources other than our bodies, as these facilities treat water coming from all urban sources, such as sewer grates. Overall, we can end up with pretty nasty things in our feces, which we may not want to reintroduce into the environment, and especially, our food.
So how do we put this resource to use safely? A big part of it is in the dosage, and how the poop is processed before it goes back into the environment. This area is well-studied, and in industrialized countries there are rules and regulations in place for applying biosolids - the solids that come from wastewater treatment - to agricultural land. Currently, the application limits are set quite low, to avoid potential risks to humans and the environment, meaning a large portion of our biosolids are used for purposes other than growing crops, such as land reclamation, forestry, and the manufacture of topsoil.
To try to solve the issue and make the best use of our poop possible, scientists are studying ways to extract nutrients in a way that doesn't include all the nasties we don't want. But solutions are certainly not one-size fits all and may not be appropriate in all parts of the world because human waste streams are really varied. They can be a mix of poop and pee, contain a lot of water, be mixed with storm drain water and maybe with toilet paper, be collected differently, etc., etc. A quick scan of the literature on the topic reveals that there is ongoing research all around the world to find out the best approaches to meet an area’s local needs.
Methods to make the best use of our waste can be especially valuable in areas of the world where it may be difficult to access commercial fertilizers, and for farmers with fewer resources to buy them. With advancements in this area of science and technology, we may be able to reduce our use of energy-intensive agricultural fertilizers which we mine or create through manufacturing processes. We can also sink more of our carbon into our soils while contributing to their better functioning. While there may be no perfect technological solution as of yet, it's a good sign that scientists are putting their minds to rethinking how to better use the fertilizers we make ourselves, and close the loop on poop.
By Renée-Claude Goulet
Cassandra Marion, PhD
Cassandra is the Science Advisor for the Canada Aviation and Space Museum. She has a PhD in geology and planetary science and exploration. Her research is focused on meteorite impact craters in the Canadian Arctic. She has more than a decade of experience in education and public outreach, developing and delivering science programming. She is dedicated to sharing her passion for Earth and planetary sciences with communities near and far, and improving science literacy in Canada.
Michelle Campbell Mekarski, PhD
As the Science Advisor at the Canada Science and Technology Museum, Michelle’s goal is to bridge the gap between the scientific community and the public — specializing in making science and technology engaging, accessible, and fun. Michelle earned a PhD in evolutionary biology and paleontology and has many years of experience developing and delivering science outreach activities. When away from her job at the museum, she can be found teaching at the University of Ottawa or Carleton University, digging for fossils, or relaxing by the water.
Renée-Claude Goulet
Renée-Claude Goulet is the Science Advisor at the Canada Agriculture and Food Museum, with over 15 years of experience in science communication. At the Museum, she develops exhibitions, educational programs, and resources that explore the science and innovation behind agriculture and food production. An Ontario Certified Teacher with a BSc in Biology and a BEd in Sciences, Renée-Claude is passionate about making complex topics accessible and engaging for all audiences.
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