Analysis Of Contact Impedance And Vibration During Deorbit Of Satellite By Electrodynamic Tether

The increasing of spatial debris leads tremendous potential safety hazard to the spatial exploration in future. Many countries have put forward some methods for reducing spatial debris. The electrodynamic tether deorbit is put forward under the background. Electrodynamic tether deorbit is a new method for reducing spatial debris, which hanges a long wire upwards or downwards from the satellite and utilizes the character which will produce electrodynamic drag when it moves in the electromagnetic field to use up energy of spacecraft on orbit, consequently, leads to a fast orbital decay and achieves the aim of deorbit. At present, the researches mainly concentrate on deorbit of LEO satellites. The paper continues the research based on former researches.1) Studied the effect of the contact impedance between terminal speres of electrodynamic tether and spatial plasma on the deorbiting characteristics of electrodynamic tether according to the electrodynamic tether deorbit system which extends upwards. Among the researches on deorbit of electrodynamic tether, calculation of impedance is one of the most important steps, which directly influences current in tether. The former researches either overlooked contact impedance or made approximation, which would influence the analysis of deorbiting characteristics of electrodynamic tether. The paper established the calculational formula of contact impedance between the positive terminal sphere and spatial plasma according to the current-voltage data of TSS-1R satellite and analysed the effect of contact impedance on deorbiting characteristics of electrodynamic tether with the classical orbit parameters method under the 13th accurate geomagnetic field model and the International Refernece Ionosphere 1990 model2) Studied transverse vibration of electrodynamic tether according to the electrodynamic tether system which extends downwards. The electrodynamic tether is influenced by many factors during deorbit, for example, electrodynamic drag, gradient force, atmosphere drag etc. Because the electrodynamic tether has light mass, big flexibility and small damp, so it easily generates transverse vibration when it is disturbed. Firstly, the paper established continuous differential equation of transverse vibration of electrodynamic tether and boundary condition with the microelement method. Because the differential equation and the boundary condition both are second order nonlinear, time-varying, strongly-coupled partial differential equations, there is no appropriate method to solve them at present, so the paper established discrete equation of transverse vibration of electrodynamic tether by Lagrange equation and analysed the transverse vibration of electrodynamic tether by the classical orbit parameters method and the Runge-Kutta method under the 13th accurate geomagnetic field model.