Analysis Of Deorbit Efficiency Of Electrodynamic Tether System And Avoidance Of Collision With Space Targets

With the deep research on space,more and more countries have devoted to space research,and the space activities of various countries are increasing.However,these space activities will inevitably leave some useless debris in space.Many on-orbit spacecrafts can not get out of the orbit in time after completing the established mission,and become the abandoned spacecrafts in space.While these space targets occupy limited space resources,they may also collide with spacecrafts in orbit,thus affecting the development of space activities and increasing the difficulty and risk for further space activities in the future.Therefore,rapid deorbit of the abandoned spacecraft has become an important research direction in the field of aerospace,and it will help to maintain the cleanliness of the space environment.In recent years,because of its light weight,low consumption and high efficiency,the deorbit method of electrodynamic tether has been regarded as an ideal deorbit method,and has attracted many researchers' attention.However,electrodynamic tether is not mature and needs further research,so it has not used in the actual spacecrafts.For the deorbit efficiency problem of the electrodynamic tether system,this paper first builds the kinematic model of spacecraft,the model of various disturbing forces and the model of the electrodynamic force and introduces the relevant reference coordinate systems,the international reference geomagnetic field model and the international reference ionosphere model.Then,based on the building of spacecraft model and space environment model,this paper verifies the effectiveness of the electrodynamic tether system for the deorbit of spacecrafts by simulation.Considering that whether the conducting wire is wrapped with insulating material will affect the current characteristics on the tether,this paper analyzes the influence of tether parameters and orbit parameters on the efficiency of spacecraft deorbit for insulated tether and bared tether respectively.For the problem of calculating the probability of collision between the electrodynamic tether system and the space target,the point by point analysis is considered.For a thin tether,even small pieces may cause the tether to break.Therefore,it is necessary to prevent the system from colliding with other space targets in the process of deorbit.In view of the special shape of the electrodynamic tether,which can not be considered as a sphere,the collision analysis is carried out for each point on the tether,and the collision probability of each point on the tether with the known space target is calculated respectively.In order to avoid the problem of the electrodynamic tether system,the collision probability is considered firstly,and take maneuvering measures to avoid the collision when the collision probability is high.Then,according to the characteristics of the electrodynamic tether system,this paper considers the method of changing the current on the tether to maneuver.Finally,the simulation results show that changing the current on the tether can effectively reduce the probability of collision and complete avoidance.