中文摘要：

针对深空探测过程中地面测控数传能力及着陆器星上功率受限等问题,文章提出了以轨道器为中继站的火星着陆器测量定位方法,旨在工程约束条件下分析地面测控站对着陆器的跟踪情况、轨道器与着陆器之间的可观性以及不同着陆点定位精度的差异,并给出相应的误差改善措施。该手段充分利用轨道器星上设备,达到提高定位精度的目的。结果表明,轨道器与着陆器之间通信的可见性要好于着陆器直接对地通信,有利于着陆器位置的确定;此外,通过几何因子和克劳美罗下限分析发现,若着陆器的着陆点位于轨道器星下点区域内,其定位精度较差。该方法充分利用轨道器与着陆器间的UHF通信链路,可为中国首次火星自主探测任务中着陆器的安全着陆提供参考。

英文摘要：

Aiming at the challenges of deep space limited telemetry capability of telemetry,tracking and command （TTC） stations and restricted power of lander,a novel two-way doppler range rate measurement based on relay orbiter is presented in this paper.This research aims to analyze tracking condition of lander from ground TTC stations and consider observability between two probes.Position precisions of different landing sites are revealed.This paper finally provides several solutions to improve lander＇s precision.This method takes advantage of orbiter＇s communication devices to increase position precision efficiently.The results indicate that observability of orbiter-lander communication is better than lander＇s direct communication to earth,which is beneficial for lander＇s position determination.By analysis of geometric dilution of precision and Cramer-Rao lower bound,when landing site is within the area of orbiter ground track,position precision will get worse.This method takes good use of ultra-high frequency （UHF） link between orbiter and lander and these conclusions could provide valuable references for lander＇s safe landing of China＇s first independent Mars exploration program.