In the early hours of February 27, Beijing time, the international scientific journal Science Progress published online the major discoveries made by the scientific research team of the National Observatory of the Chinese Academy of Sciences in the field of deep lunar exploration. Using a lunar radar on the Jade Rabbit-2 lunar vehicle, the team first revealed the geological layering at a depth of 40 meters underground in the landing area on the back of the moon, and found that the underground material consists of low-loss lunar soil material and a large number of rocks of different sizes.
The results of this study are of great significance to understand the impact process for the transformation of the lunar table, the scale and history of volcanic activity.
On January 3, 2019, Beijing time, the Chang’e-4 probe made a successful landing at the bottom of the Von Kamen impact crater in the oldest and largest Antarctic-Aitken Basin on the back of the moon. The lunar radar, like a CT device for the moon, started work at 9:29:35 a.m. on January 4, 2019, based on data detected by the 500 MHz high-frequency channel radar over the previous two months. Based on the material parameters and radar images obtained, three different subsurface formation units were identified along the 106-meter path of the lunar rover at a depth of 40 meters. The first unit is a fine moon loam 12 meters from the moon’s surface to the ground, with a small amount of rock embedded in it, which forms on top of multiple impact craters stacking sputters, which may come from the surrounding Finson and Von Carmen L impact craters. Unit 2, from 12 to 24 meters underground, is the region with the strongest echo intensity on the radar image, indicating the presence of large numbers of stones inside, and even the formation of gravel layers and piles of rubble, indicating that the sedimentation of sputtering is not only carpet-like spread, but also accompanied by cutting, mixing, and Excavation and structural disturbance of secondary impact craters are complex geological processes. The third unit, which alternates between 24 and 40 meters underground, and radar echoes alternately, is a deposit and weathering product of sputters of different periods and older sputters. Radar signals below 40 meters are weak, and high-frequency channel radar signals cannoine their physical properties. Combined with the geological history of the region, it is estimated that the complete lunar basalt cover is greater than 40 meters below the lunar surface near the landing site of the Chang’e-4.
The team said the study obtained the first radar image of the subsurface shallow layer on the back of the moon, the characteristic parameters of matter under the moon, and the sequence of the formation inside the sputter, using direct in-place measurements of the lunar radar. For the first time, humans have demystifyed the underground structure on the back of the moon, greatly improving our understanding of the history of lunar impacts and volcanic activity, and bringing new revelations to the study of geological evolution on the back of the moon. (General Station CCTV reporter Shuai Junquan)