Deorbiting Dynamics of Electrodynamic Tether

Abstract

rzhong@yorku.caAccepted 28 August 2011This paper studies satellite deorbit using electrodynamic tether (EDT) propulsion. Gaus-sian perturbation equations are used to model the orbital dynamics of EDT with envi-ronmental perturbations of electrodynamic force, aerodynamic drag and the effect ofEarth’s oblateness. Differential equations for the induced voltage-current across EDTare derived and solved with boundary conditions determined by mission objectives andhardware devices. A simplified analytical method for solving the equations is proposed toimprove computational efficiency. Simulations find that the orbit of a satellite deorbitedby EDT will become elliptical in near polar orbits due to the higher-order perturbationof Earth’s magnetic field. This is beneficial for the near polar orbits where the electro-dynamic force is less effective, because the atmosphere at a lower perigee will providelarger air drag to dissipate the orbital kinetic energy of satellite faster. Moreover, weproved that the polarity reverse of the induced voltage/current across EDT in near polarorbits does not affect the kinetic energy dissipation by the current induced Lorentz force.Compared the decay by air drag only, the orbit decaying time of a satellite with EDTwill be reduced by three and two orders of magnitudes in the equatorial and polar orbitsrespectively.Keywords: Electrtodynamic tether; deorbit; dynamics; tethered satellite; magnetic field.