双站跟踪模式下“嫦娥4号”中继星定轨仿真分析

A Simulation Study of the Orbit Determination Ability for Chang’E-4 Relay Satellite——Magpie Bridge Under Dual-Station Tracking Mode

位于地月平动点的探测器因为较差的观测几何,需要地基USB/UXB与天文VLBI长时间的联合跟踪数据获取稳定精确的轨道。提出了利用中国深空网双站共视跟踪平动点探测器,获取双程、三程测距及VLBI测量数据,解算探测器精确轨道的模式。以“鹊桥”卫星为分析对象,首先评估中国深空网对“鹊桥”的跟踪能力。然后分析不同观测组合模式下的定轨计算精度。结果表明:双站共视约束下,深空站每天对“鹊桥”跟踪弧长大于5h;使用长于6h的双站跟踪数据进行定轨,系统差的解算更有利于轨道精度提升;跟踪时长超过2天时,必须在轨道解算的同时估计光压系数,并有望实现优于百米的轨道精度。

Limited by the poor observation geometry,a long-term joint tracking data from the ground-based USB/UXB and the astronomical VLBI is required to get the accurate orbit of spacecraft located at the Earth-Moon L2 Libration point. A dual-station tracking mode is proposed to obtain two-way and three-way Ranging and VLBI tracking data to solve the precision orbit. Taking the “Magpie Bridge” satellite as the analysis object,the tracking ability of Chinese deep space network is analyzed first. Then the accuracy of orbit determination with different observation combination is simulated. The results show that under the common-view constraint,the deep-space stations can track Magpie Bridge more than 5 hours per day. To determine the orbit with tracking data longer than 6h,it is better to estimate the systematic bias of ranging data. Once the tracking arc reaches more than 2 days,the solar radiation pressure is expectedto achieve an orbital accuracy better than 100 meters.