Selecting Orbits for LEO Constellations: SSB/CW communications

摘要

Those interested in selecting orbits for satellites operating in the Amateur Satellite Service face a number of questions. These include, "Can we get there?", "Will the environment be harsh or relatively benign?" and "Do we want to go there?" Techniques for evaluating constraints related to orbit accessibility and spacecraft environment are straightforward. However, there are no standard approaches for evaluating how desirable an orbit will be to potential users or for comparing options.This paper discusses the current status of an ongoing project to identify quantitative criteria and procedures for rating the desirability of specific orbits from the perspective of a user operating in the Amateur Satellite Service. The emphasis here is on SSB/CW analog missions and orbits realistically within the reach of the radio amateur satellite program.Several measures are discussed. These include Total Coverage Factor, which describes total quantity of service, and Average Daily Access Time, which characterizes the geographical distribution of service. Examples apply the measures to both single spacecraft and constellations. Orbits investigated include Low Earth, Intermediate Circular, Geosynchronous, and Molniya types. Software for calculating ADAT for constellations is published here so readers can evaluate other constellations of interest. Since radio amateurs have only had an opportunity to work with a limited selection of orbits, some of the results may be surprising.