Tradeoffs for Selecting Orbital Parameters of an Earth Observation Satellite

Selection of orbital parameters for earth observation satellites is the most reflective factor upon fulfillment of the space mission requirements. Practically, straight forward approach for selection of these parameters does not exist. Therefore, it is necessary to follow a complex process that requires tradeoffs among the different parameters and the correspondingorbit-related requirements. Multiple mission requirements often drive the orbit to different or even opposite trends. For Earth observation satellites, the most important orbit-related requirements are the Earth coverage, payload performance characteristics, ground communication, environment and survivability, orbit life time, availability of launch vehicleand legal and political constraints. In this work, analyses of how each orbital parameter would affect these requirements are introduced. Then the tradeoffs for compromising among contradictions are presented. To demonstrate with numerical example, a mathematical modeling for the correlations among altitude, revisit time, ground resolution and a singlesatellite slewing maneuver angle is developed. To implement for large scope of the mentioned parameters, a corresponding Matlab computer program is also developed. As an output, four parametric charts representing the correlations among altitudes, satellite slewing maneuver angle, ground resolution and the revisit time are obtained. The revisit time works as a parameter in these charts. Finally, a demonstrative tradeoff is introduced via those charts.