As of 22th March 2021 Monday, The CNSA –China National Space Administration Belt and Road Initiative Lunar Mission……Chang’e-4 successfully awakened completed the 28th day of the work period after the Chinese Lunar New Year – year of the OX got back to work Chang’e 4 completed the 28th day of work……. The Chang’e 4 lander and the “Yutu 2” lunar rover finished their 28th day of work at 2 o’clock on March 21 and at 17:09 Hong Kong – Beijing Time on March 20, and entered the moon night Hibernate. Up to now, the Chang’e 4 lander and the “Yutu-2” lunar rover have survived 808 Earth days on the moon. The lunar rover travelled about 30 meters during the day and the accumulated mileage was 682.77 meters…
Chang’e-4 completed its 28th day of work, and scientific research revealed the source of the stones in the inspection area
The Chang’e-4 lander and the “Yutu-2” lunar rover ended their 28th day of work at 2 o’clock on March 21 and at 17:09 on March 20, respectively, and entered moon night dormancy. Up to now, the Chang’e 4 lander and the “Yutu-2” lunar rover have survived 808 Earth days on the moon. The lunar rover travelled about 30 meters during the day and the accumulated mileage was 682.77 meters.
Researchers systematically analysed the detection data obtained by Chang’e-4, and obtained a series of scientific results on the mineral composition of the landing area, the history of topographic and geological evolution, the degree of lunar soil space weathering, and the shallow underground structure. Recently, the research results of the State Key Laboratory of Remote Sensing Science, Institute of Aerospace Information Innovation, Chinese Academy of Sciences, were published in the international journal “Journal of Geophysical Research: Planets”. By analysing the spectral characteristics of the stones in the inspection area, the scientific research team concluded that the stones are likely to originate from the ancient Finsen impact crater, and the spatial distribution characteristics indicate that they are freshly exposed impact crater spatters. These rocks were originally buried in the lunar soil after being sputtered by the Finsen impact crater. Later, they were exposed on the lunar surface due to the impact and excavation of the spatter from the Vega impact crater.
A number of studies revealed that the Chang’e-4 landing area was covered by spatter from the Finsen impact crater formed 3.5 billion years ago. After a long period of evolution, these spatters formed a layer of fine-grained lunar soil about 12 meters thick. During the 3rd and 13th day of the month, the “Yutu-2” lunar rover found more rocks in the inspection area (Figure 2). The “Yutu-2” lunar rover obtained the spectra of two representative rocks and a panoramic image of the surrounding landforms through detailed in-position detection.
The results of the spectral comparison show (Figure 3) that the spectral absorption characteristics of the rocks are closer to those of the Finsen impact crater material, but are quite different from the spectral absorption features of the basalt inside the von Karmen impact crater. This shows that these rocks are not native basalts, and they are most likely derived from the spatter of the Finsen impact crater.
The rocks discovered by the “Yutu-2” lunar rover during the 13th day of the month are mainly distributed around an impact crater. The overall density of the rocks gradually decreases as the distance from the impact crater increases, and some rocks are distributed in chains along a specific direction (Figure 4). The spatial distribution characteristics of the rocks indicate that they are sputtering from the current impact crater. The impact crater has an elliptical shape with a northwest-southeast direction along its major axis. The continuous (micro) meteorite impacts and the thermal expansion and contraction caused by the temperature difference between day and night caused the exposed rocks on the moon to gradually shatter and disappear within tens of millions of years. The large number of rocks remaining around indicates that the impact crater is a fresh impact crater, and the exposure time of these rocks is relatively short.
Research results have shown that a sputtering pattern of the Vega impact crater located in the northwest of the landing area just passes through the area near the landing site, and secondary impact craters formed by spatters are often seen in the splashing pattern. In the inspection area of “Yutu No. 2”, several fresh impact craters at the meter and sub-meter level with fragmented materials inside and around it can indeed be observed (Figure 5). Based on the inference of the long axis direction of the elliptical impact craters, these fresh impact craters should be secondary impact craters formed by the sputtering of the Vega impact crater.
Based on the above analysis, this study believes that the stones observed by the “Yutu-2” lunar rover actually originated from the ancient Finsen impact crater. They were originally buried in the lunar soil in the landing area. Later, they were impacted by the spatter of the Vega impact crater. Excavated and exposed to the moon’s surface. The dating of the Vega crater reveals that these rocks have existed on the lunar surface for about 16 million years (Figure 6).
Dr. Sheng Sheng, Researcher Di Kaichang, Researcher Yue Zongyu, State Key Laboratory of Remote Sensing Science, Institute of Aerospace Information Innovation, Chinese Academy of Sciences
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