The main objective of the mission is the study of the surface and of sub-surface lunar, to better understand the geology of our satellite and the underlying internal layers, with an analysis of the mineralogical and topographical composition; on the sidelines, Chang’e 4 is also dealing with radio astronomy surveys, with the aim of capturing radio waves in a region of Space free from “terrestrial interference”, and of the analysis of the solar wind, that is the flow of charged particles from the Sun. And again: another experiment involves testing the possibility of growing plants on the lunar soil, in conditions of very low gravity.
Certainly very ambitious goals, to achieve which landers and rovers have so far spared no effort, giving us an unprecedented glimpse of the hidden face of the Moon. Just after his arrival, for example, the lander camera has took eighty photos of the landing site which, composed together, revealed a 360-degree panorama of the lunar ground, and a video of the maneuver, created through the re-elaboration of over 4,700 photos taken by the camera.
In January of the following year, when the rover had traveled about 350 meters studying the rock formations of the satellite, other very interesting data and images came from the Terrain Camera mounted to the top of the lander. And again: at the end of February 2020 Chang’e 4 revealed that under the hidden face of the Moon, covered by an expanse of very fine gray dust (the so-called rule: we will be back soon), several “geological layers” follow one another, produced by the impacts of the asteroids that have shaped the lunar surface for billions of years. Chang’e 4’s observations reached 40 meters below the surface, an important depth.
The news of Yutu-2
We come to today: the new discoveries of Yutu-2 mainly concern the composition of the surface of the hidden face of the Moon, and in particular the rule. As he explains Astronomy.com, one of the first elements to capture the attention of scientists is how bumpy the lunar soil was, especially compared to the one traveled in 2013 by another rover, Yutu, which, on the other hand, had landed on the other side of the satellite.
The wheels of the rover, as well as the body of the Chang’e 4, appear completely covered with a fine powder, evidently collected during the “walk” on the lunar soil. According to the researchers, this can be explained in light of the fact that the surface of the hidden side is older, in geological terms, compared to that of the visible side, in the sense that the volcanic activity stopped earlier, for reasons still unknown. In fact, when the lunar soil – composed, in fact, of a material called regolith – is exposed to spatial “bad weather” for millions of years, it repeatedly absorbs the impacts of micrometeorites (it is the so-called process of space weathering). These impacts tend to “Pulverize” the regolith into finer particles, to melt it and finally to make it clump into larger glassy globes, of irregular shape. The fact that the terrain on the far side of the moon is so “lumpy” is consistent, according to the study just published, with the fact that it is geologically older, in the sense that the dust agglutination process took longer.
Another recent discovery of Yutu-2 – which a few days ago marked the distance of a kilometer traveled on the lunar soil – concerns what, in a photo taken from far away, appeared to be a mysterious cube lying on the surface: approaching, the rover revealed that (of course) it is not an alien artifact, but a rock whose shape actually resembles that of a rabbit eating carrots. Power of coincidences, Yutu really means “moon rabbit”, a very popular creature in Chinese, Korean and Japanese folklore.