The Armstrong limit, often called Armstrong's line, is the altitude that produces an atmospheric pressure so low (0.0618 atmosphere or 6.3 kPa (1.9 inHg)) that water boils at the normal temperature of the human body: 37 °C (98.6 °F). It is named after Harry George Armstrong, who founded the U.S. Air Force’s Department of Space Medicine in 1947 at Randolph Field, Texas. Armstrong was the first to recognize this phenomenon, which occurs at an altitude beyond which humans absolutely cannot survive in an unpressurized environment. The altitude is variously reported as being between 18,900–19,350 meters (62-63,500 feet, or about 12 miles (10 nmi)).
Other articles related to "armstrong limit, limit":
... At or above the Armstrong limit, exposed bodily liquids such as saliva, tears, and the liquids wetting the alveoli within the lungs—but not vascular blood (blood within ... vacuum notes the likely result of exposure to pressure below that associated with the Armstrong limit "The subject later reported that.. ... A pressure of 47 mmHg—the Armstrong limit—is one‑sixteenth that of the standard sea level atmospheric pressure of 760 millimeters of mercury (1013 hPa) ...
... The Armstrong limit describes the altitude associated with an objective, precisely defined natural phenomenon the vapor pressure of body-temperature water ... In the late 1940s, it represented a new fundamental, hard limit to altitude that went beyond the somewhat subjective observations of human physiology and the time‑dependen ... Pressure suits had long been worn at altitudes well below the Armstrong limit to avoid hypoxia ...
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