基于中继测量的环月探测器定轨能力分析

嫦娥四号月球探测拟首次实现月球背面的软着陆,测控与数传依赖地月L2平动点的中继卫星,并有望获取四程测量与星间测量数据。对基于中继测量的环月探测器测定轨能力进行了仿真分析,结果表明,中继卫星可较好地实现环月探测器连续跟踪;在定轨能力方面,中继卫星自身轨道精度是制约环月探测器定轨精度的重要因素,当跟踪弧段达到5h以上时,定轨精度趋于稳定,但轨道精度较中继卫星的轨道精度相差1个量级;对于星间链路测量,除中继卫星自身的轨道精度外,星钟的稳定性是制约定轨精度的另一个重要因素,如果辅助以每天1h的地基跟踪亦可实现优于百m的定轨精度。

A Simulation Study of Orbit Determination for Lunar Probe via Tracking and Data Relay Satellite

Chang'E-4 will have a soft landing on the far-side of the moon for the first time.The tracking and data transmission for Chang'E-4 will depend on a tracking and data relay satellite on a Lissajous orbit around the Earth-Moon L2 point,and four-way ranging measurement is expected to be obtained.The capability of orbit determination for Chang'E-4 is studied by simulation.The results show that a tracking and data relay satellite can realize a near full time tracking for the lunar probe.In terms of orbit determination capability,the orbital accuracy of tracking and da ta relay satellite is an important constraint.Once the tracking arc reaches 5 hours,the orbit solution for the lunar probe tends to be stable.However,orbital accuracy is still one order of magnitude lower than that of tracking and data relay satellite.For inter-satellite tracking,the stability of the satellite clock is another constraint.With one hour auxiliary ground station tracking every day,an orbital accuracy of 100 m can be achieved.