Collision-avoidance strategy for a spinning electrodynamic tether system

Spinning electrodynamic tether systems(SEDTs)have promising potential for the active removal of space debris,the construction of observation platforms,and the formation of artificial gravity.However,owing to the survivability problem of long tethers,designing collision-avoidance strategies for SEDTs with space debris is an urgent issue.This study focuses on the design of collision-avoidance strategies for SEDTs with an electrodynamic force(Ampere force).The relative distance between the debris and the SEDT is first derived,and then two collision-avoidance strategies are proposed according to the two different cases.When debris collides closer to a lighter subsatellite,a stationary avoidance strategy is proposed to change the spatial position of the subsatellite by adjusting only the angular motion of the tether,which maintains the original orbit of the SEDT.When debris collides closer to a heavier main spacecraft,a comprehensive avoidance strategy is proposed to change the spatial position of the SEDT by slightly modifying the orbital height and changing the tether angular motion simultaneously.The numerical results illustrate that the proposed strategies promptly avoid potential collisions of an SEDT with space debris without significant changes in the orbital parameters of the SEDT.