On July 23, 1972 the National Aeronautics and Space Administration launched its first Earth Resources Technology Satellite (ERTS-1), using launch facilities at Vandenberg Air Force Base near Lompoc, California. From an orbital altitude of nearly 570 miles this unmanned satellite is photographing all cloud-free portions of California every 18 days and will continue to do so for an estimated 12-month period. Scientists of the University of California, in cooperation with those from the California Department of Agriculture and other state agencies, are studying the extent to which information extracted from such photographs can facilitate the management of California's agricultural resources. As illustrated by the cover photo, each “frame” of ERTS-1 photography covers more than 10,000 square miles. Nevertheless, when such a space photograph is enlarged, agricultural features as small as 100 feet across can be discerned (see pages 8 and 12). Many crop types and rangeland conditions can be inventoried, and land use categories can be recognized on such space photos when supplemented with only limited amounts of aerial photography, and direct on-the-ground observation. Results obtained to date indicate that careful interpretation of sequential space photography of the type currently being obtained by ERTS-1 can greatly facilitate the monitoring of crop development and land use change, thereby facilitating the management of California agricultural resources.

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