Learning how microbial spores are transported by air is important to biology, agriculture, and medicine. Besides spreading crop destruction, microbial spores produce allergic responses in some human beings. To obtain the facts, not only the biology of micro-organisms but also the weather factors that induce the flight of mature spores must be known. Thus, both biological and meteorological problems are involved. Data obtained under a NASA contract with the General Mills Electronic Division (now part of Litton Industries, Inc.) indicate that spores of fungi are present in low numbers in the stratosphere. A reservoir of spores exists which cannot be brought down by the normal scrubbing mechanisms of rainfall and other meteorological disturbances in the troposphere. This finding has important implications for reducing the spread of agricultural crop diseases and for protecting persons suffering from allergies. This project has indicated the necessity for designing novel biological samplers for use in the stratosphere. Such samplers will aid in determining various pollutants of the atmosphere. The NASA program for developing sterile spacecraft for the biological exploration of Mars will contribute improved methods of sterilization that can be applied to the canning industry. Studies on sterilization at low temperatures for long periods of time are being supported by NASA at the Massachusetts Institute of Technology and the Communicable Disease Center and the Sanitary Engineering Center of the Public Health Service. The developing capability is making possible the heat sterilization of products that never before could be thoroughly sterilized. In preparing for missions to search for extraterrestrial life, research on the psychrophilic or cold bacteria, on halophytic or salt bacteria, and on specialized bacteria and other organisms growing in extreme environments is defining the extremes under which life can exist. Increased knowledge about organisms that can grow in or on refrigerated, dried, or salted foods and other materials should have practical applications for food storage and preservation. Research on psychrophilic bacteria is being conducted by Whirlpool Corp. and the NASA Ames Research Center. Theoretical studies of Martian life involve investigations of plant and bacterial spores. Many of these forms are spoilage organisms and some produce lethal toxins. This work has potential importance for food processing and for obtaining more precise knowledge of how wounds become infected. The program for investigating possible forms of life on Mars includes a thorough study of anaerobic micro-organisms. This research has led to the discovery of new types of nitrogen-fixing bacteria other than the familiar types found in the root nodules of leguminous plants. Thus, it may be possible to use these microorganisms, or the principles involved, in the incorporation of vital atmospheric nitrogen into terrestrial soils which are now unproductive.