Practical Operation Strategy for Deorbit of an Electrodynamic Tethered System

摘要

This paper presents an operation strategy employing electric current switching for deorbit of an electrodynamic tethered system. The electric current in the tether experiences some unexpected changes due to its plasma environment and thermal conditions. Libration control through current switching, in which only the on/off status of the current is determined, can avoid such changes and unexpected instability. A simple control law to determine current switching to stabilize both in-plane and out-of-plane libration is presented. A new stability function is also presented to facilitate evaluating the stability of a tethered system on an elliptic orbit. The effectiveness of the libration control strategy and the stability function is demonstrated through several numerical simulations. It is clearly indicated that the stability function and a switching control toward a periodic solution facilitate an appropriate stability evaluation and an efficient libration control. The control strategy is considered to be easily materialized in actual electrodynamic tethered systems, and enables a more rapid and secure deorbit.