Introduction  The atmosphere presents an extreme habitat for life. Much as tiny dust particles float in the air around us, microorganisms can become aerosolized and disperse into the air. A myriad of disruptive events, including storms, volcanic activity, meteor and comet impacts, and human activities, may transport microorganisms into the atmosphere.  Microorganisms have been detected in the atmosphere up to the lower mesosphere and may be present at even greater altitudes. Unfortunately, an optimal method for sampling the middle to upper atmosphere has not previously been developed.  Proposed is the large-scale collection of biota from the middle to upper atmosphere using the System for Collection of Atmospheric Biota (SCAB) designed by the 2007 NASA Ames Academy for Space Exploration. The SCAB utilizes a pressure gradient to draw air though a filter, depositing microorganisms and other particulate matter. Though initially designed for utilization aboard a high atmospheric jet, the SCAB may be deployed aboard other airplanes, balloons, and possibly rockets. System for the Collection of Atmospheric Biota (SCAB) 2007 NASA Ames Academy for Space Exploration Review of Literature  In the early 1900’s, small samples of air were taken on airplanes at low elevations and sampled for microbes. In 1937, a group from the Massachusetts Institute of Technology identified sixteen bacteria and nineteen fungi in the atmosphere over Boston from an elevation of ~460m up to 5km (Proctor and Parker 1938).  In the 1970’s, collection and detection of bacteria and fungi in the middle mesosphere (48-77km elevation) was performed with rockets (Imshenetsky, Lysenko, and Kazakov 1978). Since that time, most sampling has been conducted with balloons and airplanes at lower altitudes.  A recent development has been the utilization of a collection plate which is placed into an air stream on board a high altitude jet. Though this system has proven useful in sampling bacteria and fungi from 20km up, the compression of the air stream and lack of flow to the plate’s surface makes this system suboptimal. Dale Griffin, Ph.D., and colleagues at the United States Geological Survey have recently utilized a venturi tube filter system for deployment and collection aboard a remote controlled aircraft at low altitude (<500m). The SCAB will be applicable at elevations and environmental extremes in which the USGS version is not. The SCAB is to be engineered for optimal collection at altitudes greater than 20km. Objectives  Development of SCAB Patent Review Pending (NASA NTR) Design Review Process and Production  Utilization in the stratosphere  Biological analyses and scientific benefit Development  Venturi Tube  Pressure gradient  Filter  Motor (if deployed on a balloon) Acknowledgements  The 2007 NASA Ames Academy for Space Exploration  Dale Griffin (United States Geological Survey); for origination of the idea and support for the project Utilization  We are proposing the utilization of the SCAB on two Global Hawk aircraft recently purchased by NASA. Science pods on the wing or fuselage section of the aircraft may be developed to house the SCAB, decreasing future deployment costs.  The SCAB may also be utilized on high atmospheric jets, balloons, and rockets. Biological Analyses  Culture in low-nutrient media  Genetic material isolation and amplification; genetic sequencing and phylogentic analysis  Epifluorescence microscopy  Determining the spatial and temporal distribution of life in the atmosphere may reveal answers to key questions about mass extinction events, genomic dispersal and evolution, and pathogen dispersal in the atmosphere. Also, microbial resistance to radiation, pressure, and temperature extremes can be studied with organisms that can exist in the atmosphere. Works Cited Imshenetsky, A.A., Lysenko, S.V., and Kazakov, G.A Upper boundary of the biosphere. App. and Env. Micro. Bio. 35(1): 1-5. Proctor, B.E., and Parker, B.W Microbiology of the upper air. Massachusetts Institute of Technology, Department of Biology and Public Health. Contribution #129, Adapted from