基于新近多探测器的月球与火星重力场模型研究

A high accurate lunar gravity field model will be solved using dual one-way range rate data of GRAIL mission. Further, the tracking data of spacecraft with various orbital configuration character such as Chang'E-1, Chang'E-2, SELENE, LRO, and historical spacecraft including LP are combined to develop a new lunar gravity field model with high resolution and accuracy. The methods of multiple datum reference unification and optimal data fusion are investigated, the contribution of various spacecraft to improve the accuracy of low degree coefficients of GRAIL model and Chang'E tracking data in lunar gravity field solution are evaluated. The lunar Love number is solved simultaneously, and used to inverse the size and status of the lunar core by combination with degree 2 coefficients, lunar limb and lunar seismic information. At the same time, through independent software development, precision orbit determination of Mars spacecraft, Martian gravity field and low degree coefficients time variant solutions are solved by using long arcs of MGS, Odyssey and MRO. The accuracy of the solution models are assessed using various methods. In consideration of Chinese near future Mars exploration, the contribution of spacecraft with different inclination and orbital height in Martian gravity field and low degree coefficients time variants are investigated by theoretical analysis and simulation. This research can provide some reference for the scientific objects of our near future lunar and Mars missions.

利用最新的GRAIL任务星间测速数据，解算高精度月球重力场模型。在此基础上，结合嫦娥一号、二号、SELENE、LRO、LP等具有不同轨道构型特征的轨道跟踪数据，研究多源数据基准统一与最优融合方法，解算高阶次高精度月球重力场模型，研究其对GRAIL重力场模型低阶次位系数的改进，评价嫦娥卫星在月球重力场模型中的贡献。解算月球拉夫数，结合二阶项位系数、月球天平动和月震信息，探讨月核大小与状态。同时，拟综合MGS、Odyssey、MRO等多个长时段火星探测器轨道跟踪数据，通过自主软件研制，开展精密定轨、高精度火星重力场模型和低阶项位系数时变量的解算，利用多种方式对解算结果进行精度评价。针对我国即将开展的火星探测计划，通过理论和仿真分析，探讨不同倾角与高度的探测器对火星重力场与低阶项时变量解算的贡献。本研究将为我国近期月球与火星探测的科学目标实施提供一定程度的参考。

我国已经实施的“嫦娥”系列任务获取了珍贵的月球科学数据，即将开展的后续月球与火星探测计划将要逐渐转变为科学导向型。鉴于此，本项目利用多种月球与火星探测器跟踪数据，开展了月球与火星探测器精密定轨与重力场解算研究。项目组保质保量地完成了任务书拟定的各项任务，取得了丰硕的成果，主要包括：（1）研制开发了一套月球与行星重力场解算与分析系统（WUDOGS），该系统经过了严格的交叉验证测试。利用此系统研究了GRAIL星间测速在月球重力场恢复中的贡献，并对GRAIL重力场模型的定轨性能进行了评价；对欧空局火星快车号的轨道跟踪数据处理，表明具有软件良好的定轨与预报精度；（2）根据将要发射的“嫦娥四号”四程跟踪模式，率先仿真分析了环月四程跟踪模式对月球探测器定轨的精度贡献；（3）对月球重力场以及月球内部构造进行了研究，特别对典型区域进行了深入的分析研究；（4）仿真分析了同波束甚长基线干涉测量方法对火星探测器精密定轨与重力场解算的精度贡献；（5）同时，作为本研究的拓展，利用最新的金星地形和重力模型，通过改进重力场的短波成分，提出了一个新的金星重力模型。