精化月球浅表层几何形态与物理特征的若干关键问题研究

Constant improvement in accuracy and resolution of the main and newly lunar exploration data as well as proposal and implementation of various mission plans for the moon have provided unprecedented opportunities and the more and higher requirements for further refinement of lunar geometric shape and physical properties. In order to solve problems in precision differences between various lunar satellite laser altimeter data, uncertainties in construction of DEMs for the moon’s surface due to satellite orbit gaps, validity and feasibility of identifying and inversing buried-structure of lunar subsurface and density interface with high degree gravity model of the moon, etc., we will study the method of complementing and merging laser altimeter data from a variety of moon orbiters and its results, gravity inversion technique as well as algorithms for information recognition and extraction applicable to the structure of lunar subsurface, relationship among the high order and degree of lunar gravity models, mass distribution together with interface scale of the moon and other critical issues. This research is aiming at filling lunar DEM voids obtained from on-board altimeter data, enhancing reliability of high resolution DEMs and revealing more explicit and implicit impact craters on lunar subsurface and mass interface. In addition, this study will help understand lunar geometric and physical properties more deeply and thus provide evidence for research on evolution of the moon in addition to reference for lunar farside landing and sample return performed in future Chang’E missions.

新近探月数据的精度和分辨率不断提高以及各类探月计划的提出和实施，为进一步精化月球几何形态与物理特性提供了前所未有的机遇和更多更高的需求。本研究拟针对现有各类月球测高数据精度差异及轨道间隙所导致的月表DEM构建的不确定性、月球高阶重力场模型在识别与反演月球浅层掩埋构造及密度界面的有效性和潜力发挥不足等问题，通过研究不同绕月卫星测高数据的有效互补与融合的方法和效果、适用于月球浅表构造的重力反演技术及信息识别与提取算法、月球高阶次重力场模型的阶次与浅层质量分布及界面尺度的对应关系等关键问题，旨在弥补测高数据获取的月球DEM中数据的空白区域，增强高精度DEM的可靠性，揭示出更多的月球浅表层显性和隐形撞击坑及质量界面。本研究深化对月球几何与物理特性的认识，将促进月球演化机制的研究，进而为我国嫦娥工程即将要实施的远月面着陆和取样返回提供参考。

本项目结合我国的探月计划，针对月球浅层表面几何形态与物理特征开展了系统研究。在月球形貌研究中，针对目前激光测高数据的不足，研究了月球的多源测高数据融合与互补的理论与方法，改进了测高数据预处理的策略，填补了测高数据空白区，重新制作了融合的DEM，并提高了DEM在月球北半球的分辨率；基于重建的DEM，分析了月壤结构与内部热流结构。在月球重力场研究中，结合“嫦娥五号”任务数据，精化了我国“嫦娥”系列重力场模型，新模型的形式误差相比于旧模型减少了两倍，并且重力地形的相关性也得到了提升，月球潮汐勒夫数k2的估计值为0.02430±0.0001；基于重力场模型，分析了地、月重力场中正常重力特征的差异；针对GRAIL重力场模型，提出了重力场模型中信号源深度与球谐系数阶次的定量关系；研究了月球浅表层典型结构的特征，包括撞击盆地、多环盆地、质量瘤、隐月海以及硅质火山等；基于“嫦娥”系列任务光谱探测数据，重新反演了月球表面氧化物丰度。