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Science-Fiction Adventure in the Far Future
Explosive Decompression

The subject of explosive decompression comes up so often on that I've decided to keep a file on the suject. In brief, if you keep your mouth *wide* open to avoid rupturing your lungs, you can expect to stay conscious in complete vacuum for ten to twenty seconds. If you are recompressed within one to two minutes, you will probably survive the experience. In short, Clarke (in _2001_) seens to have gotten it about right, since Bowman manages to close the airlock in the ten seconds of consciousness he has available..

"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."

Among other things, it has the only published discussion I've ever seen of the JSC (well, it was MSC then) suit technician who spent 20 seconds in vacuum in Dec 1966 when a suit umbilical came loose during a vacuum- chamber test. The pressure drop was slowed somewhat by the remaining section of hose, so it wasn't fast enough to cause lung damage.

He passed out, presumably from anoxia, after 12-15s. Pressure began to be restored at 20s and was well up at 27s, at about which time he regained consciousness. He was apparently uninjured, and aftereffects were minor and temporary.

Henry Spencer comments:

>Ebullism (Precious Bodily Fluids vaporize at body temperature):
> "Small pockets of gas can be detected beneath the skin
> within two to three seconds after exposure ..."
> "Gas evolution can also be detected in the abdominal cavity
> after seven to ten seconds, and within the heart and great
> vessels after about twenty seconds."

Roth says that vapor bubbles form in the bloodstream essentially instantaneously -- delays under 1s -- but initially are not serious enough to stop circulation. Eventually they are. Worse, these bubbles begin as water vapor, but then they start to pick up dissolved gases from the blood... and while the water vapor will condense out almost instantaneously on repressurization, the gases redissolve much more slowly, and the resulting long-lived bubbles are potentially a very serious threat. There are medical countermeasures, which Roth discusses, but most of them unfortunately rely on gravity (for example, a well-chosen prone position -- on one side at about a 30-degree head-down slope -- keeps bubbles in the heart away from the valves and gives time for the bubbles to dissolve or be dealt with medically).

Gregory Bennett adds:

Incidentally, we have had one experience with a suit puncture on the Shuttle flights. On STS-37, during one of my flight experiments, the palm restraint in one of the astronaut's gloves came loose and migrated until it punch a hole in the pressure bladder between his thumb and forefinger. It was explosive decompression, just a little 1/8 inch hole, but it was exciting down here in the swamp because it was the first injury we've ever head from a suit incident. Amazingly, the astronaut in question didn't even know the puncture had occured; he was so hopped on adrenalin it wasn't until after he got back in that he even noticed there was a painful red mark on his hand. He figured his glove was chafing and didn't worry about it.

The whole story didn't come out until the suits were back home and a suit technician was setting up to clean that glove; he discovered the dried blood on the outer TMG (thermal micrometrioid garment) and then found the wayward palm restraint bar. What happened: when the metal bar punctured the glove, the skin of the astronaut's hand partially sealed the opening. He bled into space, and at the same time his coagulating blood sealed the opening enough that the bar was retained inside the hole.

The best estimate we've been able to get from the flight surgeons about how long an astronaut might survive a catastrophic suit failure is "several tens of seconds to very few minutes" with almost certainty for detectable permanent damage.

Geoffrey A. Landis,
Photovoltaics branch, NASA Lewis Research Center
Nyma, Incorporated, Brook Park, OH

From: GLANDIS@LERC.NASA.GOV (Geoffrey A. Landis)
Subject: Re: Effects of Explosive Decompression
Date: Fri, 12 Aug 1994 16:01:24 -0400