基于LOLA数据的冯·卡门地区地形特征分析

Topography Characteristics Analysis of Von Kármán Crater Using LOLA Data

冯·卡门(Von Kármán)撞击坑位于南极-艾肯(South-Pole Aitken,SPA)盆地西北部,为"嫦娥4号"的预选着陆区。本文基于LRO卫星LOLA数据,分别采用最大平均值法、均方根高程法和盒维数法,得到并分析了冯·卡门地区的坡度、粗糙度和分形维数等地形参数信息。结果表明:冯·卡门撞击坑的海拔低,其中坑底最南部海拔最低,其余地区海拔相对较高;冯·卡门撞击坑内存在很多小的撞击结构:冯·卡门撞击坑平均坡度为1.3°,小于2°的地区约占盆地底部面积的85%;粗糙度值小于20 m的区域占95.1%;整体上有较大的分形维数。上述结果说明冯·卡门撞击坑整体上地形起伏小,结构稳定。统计结果表明:冯·卡门撞击坑南部、东南部及西北部地区都有较小的坡度、粗糙度值和较大的分形维数值,可满足探测器的着陆要求。与"嫦娥3号"着陆区地形的对比表明,冯·卡门撞击坑内部的地形条件要优于"嫦娥3号"着陆区。

Von Kármán crater, located in the northwest of SPA, is the candidate landing site for Chang＇e-4. In this paper,LOLA（onboard LRO satellite） data are processed by the maximum mean method, the root mean square height method and the box counting method respectively to acquire and analyze the slope, roughness and fractal dimension information of Von Kármán crater.The results show that the elevation of Von Kdrman crater is low and the most-south area has the lowest elevation and the rest areas have respectively higher elevation. There are many impact structures in Von Kármán crater. The mean slope of Von Kármán basin is1.3° and there are about 85% areas having the slope less 2°. There are 95.1% areas having roughness of less than 20 m and the FD（Fractal Dimension） of the whole Von Kármán basin is high. All of these show that Von Kdrman basin has smooth topography and stable structure. The statistical results hint that the south, southeast, and northeast parts of Von Kármán basin have lower slope, lower roughness and higher FD, which makes the basin is appropriate for the Chang＇e-4＇s landing. What＇s more, the comparative analysis presents that the topography condition in Von Kármán basin is better than that in Chang＇e-3 landing area.