Naked Science Forum
General Science => Question of the Week => Topic started by: thedoc on 08/07/2013 15:13:00
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I have a theoretical question about being exposed to outer space. If a person were to be instantly exposed to outer space, perhaps something like an astronaut opening his/her space suit while floating outside their vehicle, would the person explode first due to the lack of air pressure, or freeze first because of the lack of heat?
Thanks,
Ahmed
Asked by Ahmed
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We answered this question on the show...
Hannah - In the vacuum of space where it’s a low pressure, water boils at a [img float=right]/forum/copies/RTEmagicC_600px-Astronaut_with_umbrella_01.jpg.jpg[/img]lower temperature. It expands, creating gas and this could possibly cause you to explode or if you're sitting in the Earth’s orbit, you'll eventually end up at about 4 degrees Celsius in the sun. If you're in-between galaxies however, with no stars or hot sun around you, you'll end up about minus 270 degrees Celsius. So, let’s firstly do an experiment to find out what would happen to our blood in space. I visited Dave Ansell, putting a glass of water as a substitute for blood into a pressure chamber to recreate the low pressure in space.
Dave - So, we’re now at about a quarter of atmospheric pressure and you can see small bubbles starting to form.
Hannah - The vacuum chamber is actually misting up with all of the water that’s evaporating from the tumbler and water is then condensing on the cooling tubes. Wow! There's just been an explosion, I think.
Dave - Biggish bubble coming up which has sprayed water. So, this is what would happen if you had a glass of blood in space. It would boil, but a human isn’t a glass of blood. Your blood is surrounded by blood vessels and tissue, so whether that means the blood will boil is another question.
Hannah - So, how can we test that? I'm not putting myself in a vacuum chamber.
Dave - As a better model of a person being in space to a vacuum, I have a nice succulent oven ready pigeon. I've now put that in the vacuum chamber.
Hannah - Oh! I can see the skin popping. There seems to be like kind of air bubbles coming out of the skin.
Dave - So, the skin is actually being lifted slightly by water vapour, and other gases trapped underneath it and they're expanding as the pressure outside it is reducing and it’s lifting some of the skin off. That might rupture some blood vessels near the surface, but the skin itself is one solid piece. It’s not really exploding.
Hannah - A pigeon isn’t a perfect model for a human as it’s been mostly bled and has had its head cut-off, and skin damaged by plucking. But these results do seem to suggest that our circulation and tissue can, to a large degree withstand the low pressure of space. Dave also adds…
Dave - Various experiments have been done on this deliberately and less deliberately. Various animals have been exposed to vacuum and they don't explode, they have various tissue damage, and possibly our eardrums will get damaged if the depressurisation is very quick. But their body's plenty strong enough to contain that pressure. And in fact, even a person has been accidentally exposed to a vacuum and he survived the experience.
Hannah - So, we’d probably asphyxiate and dry out rather than explode and I’ll be having a slightly desiccated roast pigeon for my supper this evening I think.
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O8)well i think that if u go barely in the space the first reaction will be boiling of ur blood and water available in ur body because there is no pressure available there and there after ur body will expand like a balloon if u are in direct contact with sun radiation u will be burn too because there is no magnetic field to protect u but if u do not comes in direct contact of radiation u will be exploded.
thanxxxxxxxxxxxxx 8D
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No, you will not explode if you are exposed to a vacuum. You may bloat because of the evaporation of your bodily fluids, but your skin and circulatory system are structurally strong enough to prevent you from exploding. However, if you hold your breath, your lungs WILL rupture.
Hypoxia (lack of oxygen) is what would kill you. On Earth, a person can hold his/her breath for a couple of minutes before fainting. In a vacuum, however, you would pass out in around 15 seconds. This is because the air in your lungs is replaced with vacuum, which then starts quickly stripping oxygen from your lungs by the same (albeit reversed) process of diffusion that allows your lungs to oxygenate your blood when in atmosphere.
As for freezing, the body does not lose heat fast enough for you to freeze instantly. Furthermore, space itself isn't necessarily cold - in Earth orbit, the temperature on the dark side of the planet is as low as -100 degrees Celsius, however on the illuminated (sunlit) side, the temperature can reach 240 degrees. Another danger is solar radiation - without the protective atmosphere of the Earth, you will develop a VERY bad sunburn very quickly.