TLE预报精度改进及碰撞预警中的应用

双行根数（Two Line Elements，TLE）是目前唯一公开发布且编目最完备的地球轨道空间目标编目数据，由于其根数的特殊性，必须配合SGP4/SDP4 使用导致其预报精度有限. 通过对TLE+SGP4/SDP4预报误差源的分析，利用历史TLE数据生成准观测数据重新进行轨道拟合，针对不同轨道高度和面积质量比情况，确定相应拟合周期，得出了基于弹道系数先验信息有效确定面积质量比的经验方法，对多个独立时段拟合后轨道根数结合数值方法的预报误差进行统计，结果表明，拟合后的TLE根数预报精度与稳定性有很大程度提升. 利用实例对拟合TLE在碰撞预警中的应用进行分析，认为该方法对航天工程中碰撞预警置信度的提高具有重要意义. 

TLE Prediction Accuracy Improvement and its Application in Collision Warning

Two Line Elements (TLE) is the only publicly available and most complete data sets of Earth orbit objects. The prediction accuracy with SGP4/SDP4 is limited. The TLE+SGP4/SDP4 prediction error sources and improvement method with historical TLE data were analyzed. A pseudo-observation data generation method was introduced. The fitting period of TLE data and the value of Δt used in generating pseudo-observation are dependent on the orbital altitude. An effective area-to-mass ratio (A/M) determination method was obtained. GPS satellites prediction error in case of η estimated or not are also tested. The improved prediction accuracy is prominent in the application of US and Russian satellites collide event. Objects were selected and their orbit were predicted with an improved TLE-numerical method. The statistical results show that the TLE prediction accuracy is greatly improved. The application of the improved TLE and possible problems were also discussed.