Electrostatic Tractor Analysis Using a Measured Flux Model

Abstract

Although spacecraft charging is often thought of as a purely harmful phenomenon, if controlled it can be used as a means of touchless actuation. If a tug spacecraft irradiates a nearby debris object with an electron beam, the tug will charge positively and the debris will charge negatively. This creates an attractive Coulomb force that the tug can use to touchlessly tug the debris object from the geosynchronous orbit into a graveyard orbit. Compared with earlier work this paper uses a more advanced charging model with isotropic fluxes for the calculation of electron and ioninduced yields, and an empirical model of electron and ion fluxes rather than Maxwellian distributions. This new model is used to calculate the attractive force for a variety of tug to debris size ratios, beam currents and voltages, and the inclusion of pulsing the electron beam. The major result of using this new charging model is that it takes more current, and thus power, than was used in prior work to charge a debris object due to the higher yields from isotropic fluxes. The electrostatic tractor concept can still move a range of large, tumbling debris objects to the graveyard orbit in a few months.