“How do astronauts brush their teeth in space?”

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?

The supplies 

One toothbrush, standard issue.

(Image pulled from the video at Science Kids)

(Image pulled from the “Chris Hadfield Brushes his Teeth in Space” video at Science Kids)

One bag full of water

(Image from the "Chris Hatfield Brushes His Teeth in Space" video at Science Kids)

(Image from the “Chris Hadfield Brushes his Teeth in Space” video at Science Kids)

One tube of toothpaste, standard issue

(Image from "Chris Hatfield Brushes His Teeth in Space" at Science Kids.)

(Image from “Chris Hadfield Brushes his Teeth in Space” at Science Kids.)

The process

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.

Related Links: 

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About Shala Howell

Writer of things ranging from optical network switching white papers to genetic testing patient education materials to historical fiction set in an 1880s asylum. When I’m not scratching my head over pesky characters who refuse to do things how I want them done or dreaming of my next book (which will of course be much easier to write than the current one), my writerly self can be found blogging about life with a very curious Nine-Year-Old at Caterpickles.com, or musing about books and the writing life at BostonWriters.wordpress.com.
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