What happens to people exposed to a vacuum?

[Wes]

"Some degree of consciousness will probably be retained for 9 to 11 seconds (see chapter 2 under Hypoxia). In rapid sequence thereafter, paralysis will be followed by generalized convulsions and paralysis once again. During this time, water vapor will form rapidly in the soft tissues and somewhat less rapidly in the venous blood. This evolution of water vapor will cause marked swelling of the body to perhaps twice its normal volume unless it is restrained by a pressure suit. (It has been demonstrated that a properly fitted elastic garment can entirely prevent ebullism at pressures as low as 15 mm Hg absolute [Webb, 1969, 1970].) Heart rate may rise initially, but will fall rapidly thereafter. Arterial blood pressure will also fall over a period of 30 to 60 seconds, while venous pressure rises due to distention of the venous system by gas and vapor. Venous pressure will meet or exceed arterial pressure within one minute. There will be virtually no effective circulation of blood. After an initial rush of gas from the lungs during decompression, gas and water vapor will continue to flow outward through the airways. This continual evaporation of water will cool the mouth and nose to near-freezing temperatures; the remainder of the body will also become cooled, but more slowly.

"Cook and Bancroft (1966) reported occasional deaths of animals due to fibrillation of the heart during the first minute of exposure to near vacuum conditions. Ordinarily, however, survival was the rule if recompression occurred within about 90 seconds. ... Once heart action ceased, death was inevitable, despite attempts at resuscitation....

[on recompression] "Breathing usually began spontaneously... Neurological problems, including blindness and other defects in vision, were common after exposures (see problems due to evolved gas), but usually disappeared fairly rapidly.

"It is very unlikely that a human suddenly exposed to a vacuum would have more than 5 to 10 seconds to help himself. If immediate help is at hand, although one's appearance and condition will be grave, it is reasonable to assume that recompression to a tolerable pressure (200 mm Hg, 3.8 psia) within 60 to 90 seconds could result in survival, and possibly in rather rapid recovery."

Note that this discussion covers the effect of vacuum exposure only. The decompression event itself can have disasterous effects if the person being decompressed makes the mistake of trying to hold his or her breath. This will result in rupturing of the lungs, with almost certainly fatal results. There is a good reason that it is called "explosive" decompression.

At NASA's Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65. He remained concious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain. The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained conciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil.

See: Human Exposure to a Vacuum.

Note that Nekovalkyrja (even earlier types) have particularly strong lungs and have been known to hold their breath successfully during decompression to survive long periods of time. Doing so, however, could cause the neko to accidentally jet themselves backwards if they exhale (this ended up killing Hanako once).

 

[Fred]

Wow. I learned something today and I actually grasped it for once. thanks Wes!

I finally understand why Roger Wilco turns into a balloon and explodes if he goes in the open shuttle bay without a space suit on (Space Quest 1).

 

[Tyler]

Actually because of the lack of air pressure in space. you'd explode because there's notihng stopping the 14 psi your body puts out from the internal environment.

 

[Yangfan]

It also depends on how fast the pressure drops. Having air slowly leak out of your spacesuit should be much more survivable than having a chunk of your ship's hull suddenly blown to subatomic particles.

Ah. The marvels of space-travel.

 

[Edto Xar'Sivaree]

I think thanks to my recent studies on what would happen to people in a vacuum I could be of assistance. There is a device called a Space Action Suit, which is designed so that only the head of a person is under actual atmosphere. The rest is an elastic suit designed to keep the person's body it a form, otherwise it would expand due to approximately 20 tonnes of weight being pressed down on you by the atmosphere at any given time.

The idea of explosive decompression is there, though. The air being ejected into space would likely pull you out a window, but the mass of the air remains in a group under zero gravity for a short period of time. You would be in oxygen for a few short moments before that happened. The Vekimens suits are based on this principle, as well as the power armour that Edtoto wears on the Heartbreaker. She has a tube that goes into her lungs that stop her from vocalizing, requiring a speaker on her suit to make the vocalizations for her. It seals her airways, but her mouth, when opened, is still exposed to space. Because heat doesn't transfer in the same way it does on earth in space, your heat would actually remain inside you... It has nowhere to go, there is nothing to transfer the heat from your body to space.

Would you explode? Maybe, but the idea of explosive decompression usually means you don't realize it's going to happen. Unless you know... You're told it will, which is unlikely. Vsauce, out!

 

[Wes]

I want to note that since I started this topic, the Star Army has adopted a survival kit for vaccuum, which includes a spacesuit and a way to repair a damaged spacesuit: https://wiki.stararmy.com/doku.php?...al_kit_type_31#e_exo-atmospheric_survival_kit