Saturday, February 03, 2007

What would happen to an astronaut who was suddenly exposed to space without a protective suit?


Chimpanzees and dogs were particularly common subjects used during decompression and recompression tests. Several of these studies determined that a subject experiencing a rapid decompression to a vacuum will retain some level of consciousness for between nine and twelve seconds. Unconsciousness only occurs once the supply of oxygen in the blood is depleted. Furthermore, a human will have no more than five to ten seconds to take any action in response to the decompression. Shortly after losing consciousness, the body will experience paralysis followed by convulsions and finally paralysis again. Water vapor also begins forming in soft tissue causing the body to swell, perhaps to as much as twice its normal volume if not constrained by a suit. Over the next 30 to 60 seconds, heart rate slows, blood pressure drops, and blood circulation stops. Gases and water vapor rapidly escape through the mouth and nose causing these parts of the body to drop to near freezing temperatures. The rest of the body cools more slowly.

Although some animal subjects perished due to fibrillation of the heart within the first minute of exposure, these cases proved the exception and an air-breathing creature will almost always recover if recompression occurs within 90 seconds. Breathing usually begins spontaneously without any need for outside resuscitation. However, resuscitation becomes impossible after heart activity has stopped regardless of recompression time.   …

Having addressed the injuries a person will likely suffer, it is also worthwhile to explain those a person will not experience. A body or head does not explode, as sometimes shown in movies and television programs, because skin and bones have enough strength to contain the higher pressure fluids within the body and prevent them from escaping outward. Blood does not boil for a similar reason. Human blood pressure is already at a relatively high pressure compared to normal atmospheric conditions. Even if the external pressure drops to a vacuum, blood vessels maintain a high enough pressure that the body's temperature remains below the boiling point of water and prevents blood from boiling. The body will not instantly freeze either because even though space is generally very cold, the fact that it is a vacuum means there is no medium to conduct heat away from the body and it cools rather slowly.

Read the whole article



No comments: