Preliminary mission planning using Interactive Graphics

The selection of satellite orbits, subject to mission and launch vehicle constraints, can be expedited using the IGOS (Interactive Graphics Orbit Selection) computer program. The program operates in a conversational mode displaying the constraints as shaded areas on a graphics terminal. Mission requirements evaluated include: earth observation coverage, radiation environment, orbit lifetime, and sun synchronization. Launch vehicle constraints consist of injection accuracy and payload capability and include the impact of launch site, and launch azimuth restrictions. Sample output is shown, the hardware and software configurations are described, and details of the mathematical model are summarized.