Air compression, however, is not practicable above 80,000 feet. Travel outside the breathable atmosphere, whether into space or to the bottom of the sea, necessitates living inside a hermetically sealed compartment, a completely airtight ecological system in which carbon dioxide exhaled by the traveler is constantly replaced by an onboard supply of pure oxygen or some combination approximating the nitrogen-oxygen composition at sea level. In this area of space flight research - space cabin environment - the Air Force achieved preeminence in the early fifties with the development of the first sealed space cabin.
The sealed space cabin had two essential precursors. One was the sealed gondola for stratospheric ballooning, used by the Swiss twins Auguste and Jean Piccard in several flights to altitudes of around 10 miles in the 1930s and in the Explorer II ascent of 1935, which carried Army experimenters Orvil A. Anderson and A. W. Stevens to 72,335 feet and set a record that stood for 20 years.42 The other was the closed underwater environment of the bathysphere, used for many years in deep-sea exploration, and of the submarine. In the fifties, Air Force research on the sealed space cabin paralleled similar work by Navy scientists on an environmental control system for the new atomic-powered submarines, which were being designed to remain totally submerged for months.43
In 1952, Fritz Haber, of the Air Force School of Aviation Medicine, drew blueprints for a sealed chamber to be used for space medicine research; at the urging of Hubertus Strughold the Air Force let a contract for its construction. The Guardite Company of Chicago delivered a completed cabin in the summer of 1954.44 "Nobody took notice of a 'sealed cabin,'" recalled Strughold. "We had to have a name that would attract attention to our work. So I named it the 'Space Cabin Simulator.'"45
The cabin provided about 100 cubic feet of living space, room enough for an ordinary aircraft seat and a panel of lights, switches, and displays to test the psychological reactions of the subject. It had systems for air conditioning, oxygen supply and carbon dioxide absorption, urine distillation, and the recycling of the distilled urine together with air moisture to provide water pure enough to drink. Cabin pressure was maintained constantly at a level equivalent to an altitude of 18,000 to 25,000 feet.46
The space cabin simulator received its first national publicity in March 1956, when Airman D. F. Smith spent 24 hours in the chamber at San Antonio, performing a number of tasks for psychological monitoring and wearing instrumentation to record his heart action, temperature, and respiration rate. During the next two years, Lieutenant Colonel George R. Steinkamp, Captain Julian Ward, and George T. Hauty, who had charge of the simulations, gradually increased the duration of the tests. On February 16, 1958, four and a half months after  Sputnik I and after seven days in the sealed chamber, Airman Donald F. Farrell stepped out to be greeted by a crowd of newsmen and by Senator Lyndon B. Johnson. In this, the most famous experiment ever run in the original space cabin simulator, Farrell had spent his week completely isolated in an environment that duplicated life inside a spacecraft in every respect except the weightless condition.47
The Farrell experiment provided no unexpected physiological data. But Hauty, chiefly interested in the psychological portion of the simulation, reported that the daily log kept by Farrell showed a deterioration from good spirits to "the seemingly abrupt onset of frank hostility." Farrell's mental condition "reached the point of becoming the single conceivable reason for a premature termination of the flight." Hauty noted that Farrell's proficiency at tasks assigned to him also deteriorated severely as the experiment progressed.48
The psychological data from the early space cabin simulator tests, as well as observation of subjects in the isolation chamber at Wright-Patterson Air Force Base, were not encouraging. Major Charles A. Berry, an Air Force physician who later would work closely with the astronauts in Project Mercury, perhaps expressed the consensus among space medicine investigators by 1958: "The psychological problems presented by the exposure of man to an isolated, uncomfortable void seem to be more formidable than the physiological problems."49
41 Stanley R. Mohler, "Wiley Post's Aerospace Achievements," Airpower Historian, XI (July 1964), 66-70; Frederick R. Ritzinger, Jr., and Ellis G. Aboud, "Pressure Suits - Their Evolution and Development," Air University Review, XVI (Jan.-Feb. 1965), 23-32.
42 Caidin and Caidin, Aviation and Space Medicine, 49-54; Eugene M. Emme, Aeronautics and Astronautics: An American Chronology of Science and Technology in the Exploration of Space, 1915-1960 (Washington, 1961), 26, 29, 30, 33, 160, 162; Auguste Piccard, Between Earth and Sky, trans. Claude Apcher (London, 1950), and Earth, Sky, and Sea, trans. Christina Stead (New York, 1956). For a useful survey of research in the physiology of high-altitude living, see From the Mountains to the Moon: Some Historical Aspects of Survival at Great Heights (undated microfilm, produced by Biomedical Laboratory, University of California at Los Angeles, NASA Historical Archives, Washington).
43 Hubertus Strughold, "The U.S. Air Force Experimental Sealed Cabin," Journal of Aviation Medicine, XXVII (Feb. 1956), 50; Hanrahan and Bushnell, Space Biology, 24-26.
44 Strughold, "Air Force Experimental Sealed Cabin," 50-51; Hans-Georg Clamann, interview, San Antonio, April 23, 1964.
45 Strughold interview.
46 "USAF School Simulates Living in Space," 49-55.
47 Emme, Aeronautics and Astronautics, 81, 95; Strughold interview; George R. Steinkamp and Willard R. Hawkins, "Medical Experimentation in a Sealed Cabin Simulator," in Otis O. Benson and Hubertus Strughold, eds., Physics and Medicine of the Atmosphere and Space (New York, 1960), 370-376.
48 George T. Hauty, "Human Performance in Space," in Gantz, ed., Man in Space, 84-108. Besides the aircraft weightless and sealed-cabin programs, the School of Aviation Medicine carried on various other research activities in space medicine. As early as 1947 scientists at the school were studying the ecological conditions on other planets. From this and other research came Strughold's The Green and Red Planet: A Physiological Study of the Possibility of Life on Mars (Albuquerque, 1953). Throughout the 1950s and to the present the Department of Space Medicine at the school has done research on the atmospheric composition of other planets, photosynthesis as a means of air supply, and other subjects.
49 Charles A. Berry, "The Environment of Space in Human Flight," Aeronautical Engineering Review, XVII (March 1958), 38; George E. Ruff, "Isolation," Astronautics, IV (Feb. 1959), 22-23, 110-111. After 1951 psychologists in several universities in the United States and Canada conducted sensory deprivation studies, laboratory experiments in which a subject was immersed in water in a blackened room and thus was deprived of his visual, auditory, and kinesthetic senses. The experiments indicated "a general loosening of the subject's ability to perceive reality and the weakening of the stable norms against which perception is evaluated." Later studies at the Navy Air Crew Equipment Laboratory in Philadelphia, the Air Force School of Medicine, and the Wright Air Development Center demonstrated, however, that stable, well-trained persons "can endure severe restrictions of their natural habitat for relatively long periods of time without significant degradation." Gerathewohl, Principles of Bioastronautics, 308, 311. See also D. Ewen Cameron et al., "Sensory Deprivation: Effects upon the Functioning Human in Space Systems," in Bernard E. Flaherty, ed., Psychophysiological Aspects of Space Flight (New York, 1961), 225-237.