I should be able to remember how this question came up. After all, The Eight-Year-Old just asked it last week. But I don’t. I’ve been watching videos of Canadian astronaut Chris Hadfield brushing his teeth on the International Space Station all morning and all the glorious words I was going to use to open up this post just went straight out of my head.
So here’s the scoop. Astronauts living on the International Space Station still have to brush their teeth every day, preferably at least twice a day. There’s no “out in space” exemption for dental hygiene.
But how do you how do you get the toothbrush wet if you can’t use flowing water from a tap? And where do you spit after if you don’t have a sink? Why doesn’t all that mess just end up in your hair? Or if you’re Chris Hadfield, in your mustache?
One toothbrush, standard issue.
One bag full of water
One tube of toothpaste, standard issue
Basically the process works like you might expect, but with a few small changes.
First, wet the toothbrush. Here on Earth, we run the toothbrush under a flowing tap. In space, that’s a terrible plan, because without gravity to keep it in line that water would get everywhere. And you really don’t want water shorting out the circuits on your space station. So instead, astronauts use a small bag filled with water. They open a nozzle on the neck of the bag, release a small ball of water, close the nozzle very carefully to avoid dislodging the water ball, and touch the toothbrush to the water (from above, not below, to keep the water ball from escaping). The toothbrush soaks up the water nicely and step one is complete.
Second, get rid of the excess water on the toothbrush. Here on Earth, if our toothbrush has too much water, we tap it against the side of the sink. This is a terrible plan in a zero gravity environment. So astronauts suck the extra water off their toothbrush before adding the toothpaste to it, being very careful to keep the bristles pointing down the whole time so that the water doesn’t float away.
Third, add the toothpaste. When astronauts put toothpaste on a toothbrush in a zero gravity environment, they add it from below the toothbrush, not above it. Also they are super careful about how much toothpaste they use, because as Chris Hadfield somewhat ominously states, “You’re going to have to clean that up later.”
Fourth, brush your teeth.
Fifth, swallow and rinse. This is the bit that was the hardest for me to watch. After brushing his teeth and acquiring the inevitable mouth full of stuff, Ironman Hadfield just swallowed the whole mess. Then he got his trusty water bottle out and put a bit of water in his mouth, swished it around, and swallowed again.
Finally, clean your brush. Perhaps not surprisingly, astronauts clean their brush by wetting it again with a dollop of water from the water bag, sucking off the water, and swallowing again.
And there you have it. That’s how astronauts brush their teeth in space. Thanks for teaching us how’s it’s done, Mr. Hadfield!
Watch the process for yourself here.
- Astronaut videos (Science for Kids)
- “Do all astronauts fly in space with just their helmets on?” (Caterpickles)