What would happen if you took off your helmet in space? (Beginner)

I was wondering what would happen if you were to remove your space helmet in space and tried to take a quick breath. Believe it or not this question was a hot debate item recently at work.

Oh, I believe it. Even most astronomers don't know what would happen. NASA, however, does know. Occasionally during astronaut training, an astronaut's helmet accidentally comes loose in a vacuum chamber or something like that. (They always survive, by the way.)

When you're exposed to vacuum, the air in your lungs is forced out through your mouth. After that, you should be able to make breathing motions normally, but there will of course be no air to breathe. You will not experience any exploding eyeballs or embolisms like you see in the movies, although you may experience the Bends (this is when your blood boils). You'll also feel the spit on your tongue and sweat on your body boil away. It's described as a fizzy feeling, like drinking soda. Otherwise, you don't feel very much. Until you die of oxygen deprivation, that is.

Page last updated on June 24, 2015.

About the Author

Dave Kornreich

Dave was the founder of Ask an Astronomer. He got his PhD from Cornell in 2001 and is now an assistant professor in the Department of Physics and Physical Science at Humboldt State University in California. There he runs his own version of Ask the Astronomer. He also helps us out with the odd cosmology question.

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