月球雨海地区三个着陆点的地质特征对比研究

Geological investigations of Luna 17, Apollo 15 and Chang'E-3 landing sites at Mare Imbrium of the Moon

雨海盆地是月球正面最显著的地体单元之一,也是月球软着陆探测的重点目标之一,迄今为止已有前苏联月球17号、美国阿波罗15号和我国嫦娥3号在该地区成功实施了软着陆探测.本文基于三次任务获取的月面影像及其他数据,对雨海地区三个着陆点的地质特征进行了对比研究,重点分析了三个着陆点的区域地质背景、撞击坑、月表石块及月壤特征.本文研究发现,月球17号与嫦娥3号均着陆于较为年轻的爱拉托逊纪玄武岩单元,在一些小撞击坑的坑壁和坑缘出露了大量玄武质石块,并且一些石块表现出柱状节理构造.而阿波罗15号着陆于较老的雨海纪熔岩平原,月表石块分布很少,在哈德利月溪内壁上出露的玄武岩表现出明显的层状特征,月溪底部和边缘出露的部分石块也观测到了柱状节理.在一些月面影像数据上观测到了一些可能的"线性"特征,本文通过光照实验证实了这些"线性"特征是由微小起伏月表在较低角度太阳光照射下引起的.三个着陆区对比分析揭示了月球撞击历史、火山活动、空间风化等重要地质过程存在较大的地区和区域不均一性,未来更多的月面就位及采样返回探测将有助于我们更全面地了解月球的地质演化历史.

The Imbrium basin is one of the most prominent geologic units on the lunar nearside, and also significant exploration target for soft-landing missions. Till now, three lunar missions, USSR＇s Luna 17, American Apollo 15 and Chinese Chang＇E-3, have successfully soft-landed and conducted surface investigation at this basin. Employing the surface images and other data acquired by the three missions, we analyze the geologic characteristics of the three landing sites, mainly focusing on the regional geologic context, impact craters, surface boulders and regolith materials. We find that, the Lunar 17 and Chang＇E-3 spacecraft landed on the relatively younger Eratosthenian mare basalt units, respectively, where massive basaltic bedrocks are exposed at the wall and rim of some small craters, and some of these exposed boulders present columnar jointing, while the Apollo 15 landed on the relatively older Imbrian lava plains, where surface boulders are seldom present. There exposed some layered basalts at the wall of the Hadley Rille, and columnar jointing structure is also observed at some boulders exposed at the rille floor and rim. We observe some possible lineaments on the surface images. We propose that these possible lineaments are caused by slightly undulant lunar surface illuminated under relatively low sun elevation angles, which is supported by our simulation experiments. The comparison of the three landing sites indicates that other important geologic processes are regionally and in-situ and sample-return missions will strengthen our Moon. impacting history, volcanic activities, space weathering and locally inhomogeneous on the Moon, future lunar surface understanding of the geologic evolutionary history of the