Grossology
- 19th Oct 2023
- Author: Katie Holland
When someone hears that they have been selected to become an astronaut, I can imagine they experience a flurry of emotions: shock, maybe a few nerves, but most of all excitement. There’s a lot of cool stuff to look forward to. It sounds like a lot of fun to float around up there, and the views look incredible. But maybe something they don’t think about as much is the gross side of space travel.
Gastronauts
Passing gas can be quite an issue in space, and that’s because of the lack of gravity. Here on Earth, gravity helps to drag everything back down towards the ground. That’s what stops us from floating away into space! It’s also, weirdly enough, what allows us to burp. The heavier liquids and solids are pulled to the bottom of our digestive tract, while the lighter gases remain at the top. When we burp, these gases are forced up and out our mouths, accompanied by a lovely baaarp sound.
While that sound alone can be enough to make people give you a funny look here on Earth, up in space it’s even less graceful. Without the influence of gravity, the solids, liquids and gases are all free to float around and mix together inside an astronaut’s stomach. That means that when the gases try to escape, they drag solids and liquids along with them. This is often described as a ‘wet burp’.
In effect, every time you try to burp in space, you throw up in your mouth. It’s very important that astronauts burp with their mouths closed, so they don’t throw up all over their crewmates. Astronauts already struggle with feeling sick in space, so a faceful of vomit certainly wouldn’t be welcomed.
Incidentally, less gas coming up as burps means more gas moving in the opposite direction. Astronauts break wind much more in space than they usually would back home, something that probably isn’t helped by their diets. In space, your sense of taste becomes a lot weaker, so astronauts tend to prefer spicy foods.
Potty training
Those spicy meals might also bring on more trips to the bathroom. Thankfully, spacecraft like the International Space Station (ISS) are equipped with functional toilets. However, like with all other aspects of becoming an astronaut, learning to use the toilet in space requires extensive training.
While there are a few different designs for space toilets, most of them use the same basic idea. Without the help of gravity to pull the astronauts’ waste down into the toilet, space toilets instead use a light suction, a bit like a vacuum cleaner. To make room for these additional systems (sometimes including a urine recycling system – astronauts drink their own wee!), the toilets themselves are designed to be more compact. On the Space Shuttle, for example, the seat opening of the toilet was just a tiny four inches wide.
Shuttle astronauts who weren’t so confident in their aim were invited to practice using the positional trainer kept at the Johnson Space Center in Houston, Texas. This non-functional replica of the Shuttle toilet contains a light and a camera, which is hooked up to a monitor just in front of the toilet. Training astronauts are treated to a view of their own ‘full moon’ as they practice correctly positioning themselves over the toilet. While this doesn’t sound like the most pleasant thing to do, it is nonetheless necessary to make sure the astronauts will be able to do the real thing in space. After all, no one wants a repeat of the Apollo 10 incident.
Keeping clean
While some astronauts have been lucky enough to have working toilets, unfortunately the same can’t be said for showers. Astronauts can’t take a typical shower in space because the microgravity causes the water to pool together into floating globs, instead of falling down over the body. It’s also very important to keep track of the water being used, as any runaway droplets have the potential to damage the delicate systems onboard. Because of this, spacecraft can’t have free-flowing water from a tap.
Instead, astronauts use pre-mixed soapy water from small pouches to wash themselves. Astronauts have compared this to taking a sponge bath when you go camping, which doesn’t make it sound too bad, but it’s certainly no substitute for a real shower. No matter how much deodorant an astronaut uses, there’s always at least a faint whiff of body odour in the air.
Potentially even worse is what happens to the dirty water afterwards. I’ve already mentioned that some spacecraft recycle astronaut wee into drinking water, but the ISS has an advanced water reclamation system that can recycle moisture from the air. This includes an astronaut’s sweat, the moisture in their breath and the damp from their dirty towel!
Of course, there’s more to keeping clean than just taking a shower. Once the astronauts are done picking the meat paste out of their teeth, it’s time to brush them. They can use a normal toothbrush and toothpaste in space, and brush their teeth in almost the exact way we do on Earth. The main difference comes afterwards. With no sinks to spit into, and little desire to keep a dirty toothpaste-covered rag around the place, astronauts opt to just swallow their toothpaste. Not the grossest part of space living for sure, but not very nice either.
When astronauts have to cut their hair or their nails, they try to do so with a vacuum cleaner to hand to capture it all before it floats away. At least, some do. Some astronauts opt to simply cut their nails near a vent to help pull all the clippings together, then vacuum them up after. But astronauts live very busy lifestyles, and don’t always have time to clean them up right away. While it’s already gross enough to leave fingernail clippings lying around for your crewmates to find, it’s even worse to not clean them up yourself.
Such a thing happened during an ISS mission named Expedition 34. Canadian astronaut Chris Hadfield has admitted to maybe not cleaning up his fingernail clippings as well as he should. Then, when mission commander Kevin Ford went to open up the vent Hadfield had used to do some maintenance, he was greeted with a sea of Hadfield’s dead fingernail clippings, which flew into his face. That probably earned Hadfield quite a stern (and well-deserved) telling off.
Sweating the small stuff
What makes the lack of a proper shower extra unfortunate is the amount of exercise astronauts have to do in space. Our daily lives here on Earth involve using our muscles a lot, which helps to keep them strong. Simply standing upright involves using a lot of different muscles, including in your legs, back and abdomen. Astronauts don’t do a whole lot of standing in space, they’re mostly free to float around. That means their muscles get much weaker, as they don’t have to work against gravity. To fight this, astronauts have to exercise for around 2.5 hours every day while in space.
As you can imagine, this gets our astronauts pretty sweaty. The sweat forms pools on the body instead of dripping down, so it has to be wiped away with a towel. Inevitably, however, their clothes capture some of this sweat too. So, what do they do with these sweaty clothes? Since water is such a precious resource, they can’t have washing machines up there. Instead, dirty clothes are simply thrown away with other waste to burn up in Earth’s atmosphere. If the astronauts were doing this every day, space living would quickly become very wasteful (and expensive too!).
So, to combat this, the astronauts have access to a limited amount of clothing. To put it simply, they just wear the same clothes until they can’t bear the smell anymore! The average astronaut will only change their underwear every two days, their shirts and socks every week, and their trousers every month. Even their sweaty exercise clothes have to last a whole week before they get a fresh set.
These sweaty clothes can actually cause much worse problems than a bad case of body odour. A surprising issue that has to be dealt with on space stations is the growth of mould. Humans produce a lot of moisture, and without the option to crack open a window, that moisture becomes trapped aboard a space station. We’ve already talked about the systems in place to capture this moisture, but some can still get trapped in hard-to-reach places. Just like here on Earth, anywhere where you have moisture, mould can grow.
One of the worst places for this is where the astronauts hang their sweaty clothes after a workout. The moisture from their clothes becomes stuck to the wall and has caused large amounts of black mould to grow. Not only is this disgusting, it’s also dangerous for the astronauts' health. It can also be a big problem if moisture becomes trapped in any onboard electronics, as fungus growth has the potential to damage the circuitry of crucial systems. It’s very important that astronauts keep on top of their mould-scrubbing to stop any spores floating around.
Skin shedding
When the astronauts are blessed with a fresh pair of socks, they have to change them very carefully. People walking around on Earth put a lot of weight and pressure on their feet. To help protect them, the body develops a thick layer of skin on the bottom of the feet, which is worn down and regrows as we walk around. While this is great for us on Earth, it’s not so useful for astronauts who aren’t doing much walking around. Without anything to wear it away, this layer of skin is free to build and build. After a couple month in space, the human body realises it has no use for this extra skin, so it gets rid of it. The skin on the feet begins to shed, sending particles of dead skin to float around the cabin.
When the astronauts change their socks, a week’s worth of skin shed is released all in one go. Letting all that dead skin fly towards their crewmates is a quick way for an astronaut to lose friends. So taking off a pair of socks becomes a very delicate process, as astronauts try to contain as much skin in the socks as possible. It also helps to change your socks near a vent, which can pull that cloud of dead skin out of the air to be cleaned up later. We’ve already learned what can happen when these vents aren’t kept clean properly, so it’s very important for astronauts to keep a vacuum to hand to clean up their dead skin chunks.
Full references / credits:
(Banner image) Grossology. Credit: © National Space Centre
(1) Sadly, astronauts can’t use their farts to push them around the cabin. Credit: NASA
(2) Video: Shuttle's Toilet Requires Special Training. Credit: NASA
(3) US astronaut Karen Nyberg demonstrates how to wash your hair in space. Credit: NASA
(4) Chris Hadfield at the 'scene of the crime' of his nail clipping felony. Credit: CSA/NASA
(5) Sweaty fabrics can cause mould growth on the ISS. Credit: NASA
(6) Lizards also shed their skin, but it’s much cuter when they do it. Credit: Brian Jones Francis CC BY-SA 2.0 (https://www.flickr.com/photos/epholio/9300623909)
