Development of space cabin tolerance criteria to trace contaminants.

F R O M the very inception of contemplated space flight, the Air Force has been vitally interested in research directed toward provision of a safe and habitable environment under the hostile conditions of space. The idea of safely sustaining man in a closed system for relatively long periods of time is not particularly new or unique. The Navy has been confronted with this problem for many years and has performed many successful missions requiring prolonged periods of submergence in the nuclear powered submarine. Approximately 40 years of research effort have been necessary to attain the underwater capabilities of today's submarine with regard to atmospheric control. Fortunately, the experience and data compi led on submarine habitability problems have direct application to space cabin function. One soon realizes, however, that although the problems are essentially alike in the two systems, environmental control problems in space craft will be greatly accentuated by both the external and internal environments of the vehicle. Just as with the submarine, one can anticipate that short, manned space missions from one to 14 days will present no major difficulties with regard to trace concentrations of toxic contaminants. The major toxicity hazard would only be of an acute nature such as in the case of a leaky refrigeration system, an accidental spill of some noxious material, or complete failure of the air filtering system. In most cases, the astronauts could protect themselves with closed circuit breathing of oxygen and, if necessary, abort the mission. The cardinal problems, then, appear to be associated with missions of