COVERAGE REGIONS - HOW THEY ARE COMPUTED AND USED

Coverage regions are important considerations in the design and use of many space systems. Applications include ground-to-space and space-to -space communications, sensor coverage, and weapon reach. The ''covera ge region'' umbrella includes ''constraint regions,'' e.g., eclipse re gions for satellite visibility issues. The fundamental building blocks are circular regions on a sphere. These are combined to form more com plex regions. Equations, based on spherical trigonometry, are develope d to compute the boundaries of coverage regions in both geographic and satellite orbit coordinates. Emphasis is placed on circular satellite orbits, but extensions to elliptical orbits are addressed. For the la tter, approaches to derive quartic solutions for satellite umbra and p enumbra entrance and exit times, and for tangents to coverage regions, are indicated. Various applications are illustrated.