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Next time you’re in space...

Don’t believe everything you see in the movies.
bob_berman_2009


At the end of some sci-fi movies (think Total Recall or Outland), the bad guy is pushed out the spaceship’s airlock. You know what happens next. He explodes.

But such scenes do not match the reality of space. In the 1960s, NASA built a bunch of altitude chambers to mimic the hostile environment of low air pressure. Volunteers experienced the conditions found at various altitudes, and a few animal tests — thankfully not very many — were conducted with even lower pressures.

The results let scientists learn how bodies would respond to sudden depressurization, and were proven correct in later accidents. (Fortunately, none of the outcomes included exploding.) In 1965, a technician testing a new space suit in an altitude chamber was exposed to a near-total vacuum when a faulty valve popped and all the air immediately rushed out. In exactly 14 seconds, the man lost consciousness and collapsed. Happily, he was being monitored — air was promptly reintroduced, and he regained consciousness without any apparent harm.

A few years later, another technician was trapped in a faulty altitude chamber. He too lost consciousness in about 15 seconds and started turning blue. His life was saved when a manager kicked in one of the machine’s gauges, breaking the seal and letting air rush in.

When an animal or human body is suddenly exposed to the vacuum of space, a number of injuries begin immediately. At first they are minor, but they quickly add up to become life threatening. The first and most visible is the instant expansion of gases in the lungs and digestive tract. A 1965 study at the Brooks Air Force Base in San Antonio proved that dogs exposed to a near-total vacuum always survived if they were “rescued” (meaning pressure was restored) within 1.5 minutes. However, they became unconscious almost immediately, with gas expelled from their bowels and stomachs, resulting in simultaneous defecation, projectile vomiting, and urination. It all looked worse than it was: They had seizures, their tongues were coated in ice, and the animals swelled up like balloons. Yet even partial repressurization made the dogs shrink back down and begin to breathe. When full pressure was restored, they were walking after 10 to 15 minutes, and an odd blindness that had befallen them wore off after a few minutes more.

But dogs kept in a vacuum just slightly longer, two minutes or more, usually died. Oddly, chimpanzees withstood longer periods in a vacuum. They lived after up to 3.5 minutes in space-like conditions without any later impairment in function.

BB0218
Ed White was the first American to perform an extravehicular spacewalk, which lasted 23 minutes. Without a cozy space suit like the one he wore, you could expect to last about 90 seconds in the vacuum of space.
NASA
Human accidents showed similar lack of long-term impairment. That technician with the faulty space suit later said his last memory before blacking out was of moisture on his tongue boiling. Indeed, we know that water instantly boils in space, even at room temperature. At any height above about 63,000 feet (19,000 meters) — called the Armstrong limit or Armstrong’s line (no relation to Neil, but named after Harry Armstrong, who founded the U.S. Air Force’s Department of Space Medicine in 1947) — water boils below body temperature. Eye and tongue moisture boils away, and no amount of externally supplied breathing air pressure (such as via a positive pressure oxygen system) will keep a person conscious. Blood won’t boil because it’s sealed under pressure within arteries and veins, but nitrogen gas bubbles quickly form in the blood, and these start accumulating until they stop the heart in two to three minutes. At the same time, the absence of pressure outside the skin pulls it outward, creating a partial vacuum around muscles and organs so that water there speedily evaporates, contributing to the swelling of the victim.

An astronaut finding herself in sudden decompression should first exhale; otherwise, the lungs will probably rupture and inject air bubbles into the circulatory system. This lifesaving breath out will be followed by 10 to 15 seconds of useful consciousness. This is the only time available to her to save her own life.

Of course, space has other perils, too, like the angry red sunburn one would get in just two minutes of direct skin exposure to solar radiation (including the fearsome UV-C we never receive on Earth’s surface). On the other hand, the sci-fi scenario of the unprotected astronaut freezing solid (Sunshine, Mission to Mars) would not happen, at least not for a long while, because body heat cannot easily go anywhere in a vacuum. Space acts like a thermos container. It preserves body heat, so staying warm is not on the astronaut’s immediate “to do” list. Only the cooling induced by the sudden water evaporation from mouth, nose, and eyes would be noticeable, creating an instant coating of ice in these areas.

Bottom line: If this ever happens to you, breathe out, use your 10 to 15 seconds wisely, and know that if your friends bring you in within 90 seconds, even though you’ll be unconscious, you should live to tell about it. There. Not so bad.

Join me and Pulse of the Planet’s Jim Metzner in my new podcast, Astounding Universe, at http://astoundinguniverse.com

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