Interlink and coverage analysis for small satellite constellations

In this article, the use of both the well-known Walker constellations and a proposed Randomic one are studied focusing on the data exchange between small satellites and their coverage of the Earth. The term Randomic is adopted to define constellations that are composed of small satellites placed in orbits occasioned by ‘catching a ride’ on launchers intended for other payloads. Thus, if on the one hand this ‘piggyback’ configuration has the merit of saving launch costs, on the other hand the small satellites will generally end up in orbits not ideally suited to their intended mission. In any case, in order to ensure an appropriate communication chain between the satellites, Bit Error Rate has to be kept below certain levels and this in turn requires keeping satellites within appropriate limits of distance and relative velocity. Following a statistical analysis over the past decade of launches, aimed at establishing the most exploitable orbits for ‘piggyback’ configurations, an investigation into the use of this type of constellation has been conducted. The comparison with an optimal Walker configuration has highlighted the better performance of the Walker and the significant reduction of mission expenditure of the Randomic constellation.