Applying multi-level topology control to satellite formations - a mobile sensor network in space

Several currently planned space missions consist of a set of satellites flying in a formation. This enables a much higher functionality of the mission compared to missions consisting of only a single satellite. The sensors present in each of the satellites in the formation enable sensing of photometric data from outer space. Using optical interferometry, the data from the individual satellite sensors is collected at a designated satellite which requires communication between the satellites, giving rise to a mobile sensor network in space. In order to gain most accurate data, the satellites must be kept in deterministic close relative positions, otherwise, the aggregated data is invalidated. Current control laws to establish reliable formations of satellites face many challenges especially for larger number of satellites. In this paper we present a distributed algorithm to scale current control laws to arbitrarily large satellite formations. This is achieved by a multi-level topology which is based on multiple weighted metrics and can cope even with the case of unpredictable metric values. We substantiate the performance of our algorithm by extensive simulations.