月地返回轨道控制误差传播及分离点位置精度分析

基于探月工程三期论证中的一条月地返回轨道,分析了影响轨道器和返回器分离点位置计算精度的误差因素，建立了相应的误差协方差传播模型。通过仿真计算，讨论了在不同修正时机下，末次修正控制误差对轨道的影响，给出了分离点位置误差与末次修正后轨道误差之间的关系，对末次修正时机和分离时机的选择与分离点位置误差的关系进行了初步分析，结果表明,适当延后末次修正时间，以及适当提前分离有助于控制分离点位置误差。

Error propagation control of Moon-to-Earth return trajectory and position accuracy evaluation of separation point

Based on a specified Moon-to-Earth return trajectory in the demonstration of the third step of lunar exploration program of China, the error factors resulting in the position error of the separation point where the return vehicle separates from the orbiter are analyzed. Then the corresponding error covariance propagation model is constructed. The impact of the different time of the last midcourse correction on the orbit error is discussed by simulation, giving the relationship between the position error of the separation point and the orbit error after the last correction. The relation between the time of the last midcourse correction and the choice of the separation height is preliminarily analyzed. The results show that properly delaying the time of the last midcourse maintenance or properly advancing the separation can help to control the position error of the separation point.