The Moon’s farside shallow subsurface structure unveiled by Chang’E-4 Lunar Penetrating Radar
Chunlai Li, Yan Su, Elena Pettinelli, S. Xing, Chunyu Ding, Jianjun Liu, Xin Ren, Sebastian Emanuel Lauro, Francesco Soldovieri, Xingguo Zeng, Xingye Gao, Wangli Chen, Shun Dai, Dawei Liu, Guangliang Zhang, Wei Zuo, Weibin Wen, Zhoubin Zhang, Xiaoxia Zhang, Hongbo Zhang
Abstract
On 3 January 2019, China's Chang'E-4 (CE-4) successfully landed on the eastern floor of Von Kármán crater within the South Pole-Aitken Basin, becoming the first spacecraft in history to land on the Moon's farside. Here, we report the observations made by the Lunar Penetrating Radar (LPR) onboard the Yutu-2 rover during the first two lunar days. We found a signal penetration at the CE-4 landing site that is much greater than that at the CE-3 site. The CE-4 LPR images provide clear information about the structure of the subsurface, which is primarily made of low-loss, highly porous, granular materials with embedded boulders of different sizes; the images also indicate that the top of the mare basal layer should be deeper than 40 m. These results represent the first high-resolution image of a lunar ejecta sequence ever produced and the first direct measurement of its thickness and internal architecture.