In January 2019, China landed its Chang’e 4 mission on the far side of the moon. The Yutu-2 rover was busy exploring the surrounding area. It still continues, despite the rover’s nominal operational mission being only three months.
Among the results of the mission was a strange material described as “gel-like”. Now an analysis of the material has revealed that it is only stone: molten breccia.
The Yutu-2 rover moved across the floor of the Von Karman crater, located in the large south pole-Aitken Basin. Inside a much smaller crater, it saw a shiny, green material.
The discovery is important. Rover was on the far side of the moon, a place we have never visited before. Was it possible for China to find something new there? Something that simply isn’t close by? After all, the lunar near and long sides are quite different.
Rovers use spectral analysis to analyze chemistry on things they find. Yutu-2 has a spectrometer, the visible and near-infrared image spectrometer (VNIS). But the problem is that spectrometry interpretation also relies heavily on knowing the background spectrometry for the area the instrument is in. And since no one, or no rover, has ever been on the far side of the moon, there is no background information.
“We have no samples from this region that would help inform the model parameters. For this reason, the exact results of the regolith composition presented in this article may not be entirely accurate, “NASA’s Dan Moriarty said in an interview on Space.com.
But the new article presents the results of a rigorous scientific analysis. The thesis title is “Impact melt breccia and surrounding regolith measured with Chang’e-4 rover.” The lead author is Sheng Gou, from the Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Sciences. The thesis is published in the journal Earth and Planetary Science Letters.
In their paper, the authors note that the spectrometry measurements were made under difficult conditions with poor lighting. But they still say that the “gel-like” substance is in fact simple molten breccia. They also say that it resembles lunar cliffs taken back by the Apollo missions.
After analyzing the rock and the surrounding areas, the researchers believe that they have a best explanation for the rock itself.
The “gel-like” rock is inside a small crater, which is inside a large crater, which is inside a huge crater. The huge crater is the south pole of the Aitken Basin, which would have created a huge melting pool upon impact. The test site is located just at the edge of the melt pool. According to the researchers, the rock is likely to be a mixture “from a differentiated melt basin or from a suite of abusive rocks”, which is the result of crater impact in the vicinity.
They say that the rock “was formed by impact-generated welding, cementing and agglutination of moonlight and breccia.”
When the Yutu-2 rover found the strange mountain, the researchers were puzzled. The team that piloted the rover paused even the normal driving activities. And the discovery made headlines around the world.
Now it is almost a betrayal to discover that the “gel-like” substance is just stone. Although it is a complex mountain, created from the influence.