基于TLE的弹道系数计算方法及应用分析

针对仅使用两行要素（Two Line Element，TLE）作为数据源的应用需求，研究了基于TLE轨道衰减的弹道系数计算方法。介绍了一种常用的基于两组TLE的直接计算法，分析TLE选取间隔对结果精度的影响；提出了一种基于多组TLE的迭代计算方法，以降低异常TLE对计算结果的影响；从弹道系数计算效果、在再入预报中的应用等方面对这两种方法进行比较分析。结果表明，两种方法各有优劣，基于多组TLE的迭代计算法稳定性更高、受TLE精度的影响更小；由于数据区间更短，基于两组TLE的计算结果对短期轨道衰减特性反应得更准确，用于临近再入时的预报效果更好。

Ballistic coefficient estimation method based on TLE and application analysis

In order to meet the requirements of research which use two line element (TLE) as data source, ballistic coefficient estimation methods based on the variation in mean semi major axis derived from TLE were studied. A direct estimation method based on two TLEs was introduced, and the influence of the TLE interval on the ballistic coefficient result accuracy was analyzed. In order to reduce the influence of outliers, an iterative estimation method based on multiple TLEs was proposed. Comparative analysis was made for these two methods. The results show that these two methods have their own advantages and disadvantages. The ballistic coefficient results estimated by the iterative method have higher stability and are less affected by the TLE accuracy. Due to the shorter data interval, the estimation results using the direct method respond more accurately to the short-term orbital variation characteristics, and this method is recommended to be used in the last phase of re-entry.