What happens if you’re thrown into space without a spacesuit?

Your body would cope better than expected in space without a spacesuit. Well, you'd still die, but at least you wouldn't explode!

16th December 2010

Asked by: Peter Green, Saffron Walden

Astronaut Ed White floats in the microgravity of space outside the Gemini IV spacecraft. Behind him is the brilliant blue Earth and its white cloud cover. White is wearing a specially-designed space suit. The visor of the helmet is gold plated to protect him against the unfiltered rays of the sun. In his left hand is a Hand-Held Self-Maneuvering Unit with which he controls his movements in space. Credits: NASA/Jim McDivitt

Astronaut Ed White floats in the microgravity of space outside the Gemini IV spacecraft (NASA/Jim McDivitt)

Surprisingly, you probably wouldn’t explode. Skin is almost completely gas-tight and strong enough to withstand a pressure differential of well over one atmosphere. You also wouldn’t instantly freeze. In a vacuum, the only way to lose heat is by radiation (which occurs very slowly for a relatively cool object like a human body) or by evaporation of fluid. You would still die of course, but it would be by asphyxiation. Your blood holds enough oxygen for about 15 seconds of brain activity. After that you’d black out, with complete brain death following within three minutes.

But if you were rescued in the first 30 seconds, you’d probably have nothing worse than ‘love bite’-type bruises over all your skin. Don’t try to hold your breath before they throw you out though. The air in your lungs will cause your lung tissue to rupture quite abruptly as it expands into your chest cavity, forcing air bubbles into your bloodstream. This will be fatal even if you are subsequently rescued.

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