Electrostatic Forces for Swarm Navigation and Reconfiguration

Abstract: In this study, we have developed a navigation scheme for a swarm of satellites equipped with both electrostatic and conventional actuators. The main features of two new concepts for formation flying control i.e. electrostatic actuation, used for active control of spacecraft charging for relative position control and equilibrium shaping, which is a behavior based swarm navigation technique are highlighted in this study. The work described in this report is divided into two main sections. In the first section, the propulsion system is investigated. The GEO region is selected for this study since, the Debye length is sufficiently high in this region and a model of the interaction between plasma and a charged spacecraft is derived. On the basis of this result the requirements for the hybrid propulsion system are defined and a new charge control strategy with two currents i.e. charging and stabilizing current is proposed. The stabilizing current Ist counteracts the natural environmental currents and drive the spacecraft potential toward zero and charging current is emitted with the acceleration voltage of desired potential level and drives the spacecraft to desired potential level in certain range. The candidate propulsion system consists of a radio frequency ion thruster engine (RIT) and an electron gun for emission of charges from the spacecraft. In the second phase of the study the applicability of the electrostatic actuation for formation keeping and reconfiguration of swarms of satellites is considered. The recently developed equilibrium shaping navigation technique has been selected to control the maneuvers of the swarm. There is a specified set of formations that can be acquired in an autonomous way by means of the ES technique and a specified set of formation can be maintained only relying upon the EA concept. The compatible formations are those that can be acquired autonomously relying upon the ES path planning scheme and maintained using only the EA. These formations enjoy both a high level of autonomy, ensured by the equilibrium shaping, and high fuel efficiency, provided by the electrostatic actuation. Exploiting the results on the compatibility, the electrostatic interaction between the SC has been considered to increase the efficiency of acquisition or reconfiguration maneuvers. In particular it has been demonstrated that the electrostatic force can be used to reduce the fuel expenditure of the whole swarm.