Reporters learned from the Institute of Geology and Geophysics of the Chinese Academy of Sciences on the 13th that based on the Chang'e 6 lunar soil samples, the research team led by researcher Li Jinhua of the Institute analyzed in detail various magnetic minerals in the lunar soil, and how their unique magnetism was generated and retained, revealing the mystery of the weak magnetic field of the lunar shell on the back of the moon and the strong magnetic field of the soil. The relevant research results were published online in the journal Nature Communications. The magnetic minerals on the moon are like a "diary" that records the evolution of the moon, preserving traces of geological events such as the evolution of the moon's magnetic field, meteorite impacts, and space weathering. However, the lunar environment is very unique, lacking air, extremely dry, and highly reducing. This makes magnetic minerals such as magnetite, which are commonly found on Earth, almost impossible to find on the Moon, "said Dr. Gong Zheng, a co-author of the paper from Nanjing University. The South Pole Aitken Basin, located on the far side of the moon, is the largest and oldest impact site on the moon. The magnetic field signal in this area itself is very weak. However, the lunar soil returned by Chang'e-6 from the basin showed extremely strong magnetism, with a magnetization level far exceeding all previous samples collected from the front of the moon. Its saturation magnetization intensity also set a record for the highest among all samples returned to the moon. Li Jinhua said, "The contradiction between weak magnetic field in lunar crust and strong magnetic field in lunar soil has become a key puzzle that scientists need to unravel." In this latest study, the research team used various cutting-edge microscopic analysis methods to discover that there are two types of magnetic particles from different sources in the lunar soil of Chang'e-6, and at least three types of metal iron particles formed after "secondary modification". The source and physicochemical properties of magnetic particles determine their different magnetic records and stability in lunar soil. Based on the weak magnetic field of the lunar crust in the landing area of Chang'e-6, but containing a large amount of magnetic carrying minerals with strong magnetism, researchers further speculate that the strong magnetic field on the northern edge of the Antarctic Aitken Basin may be due to the accumulation of thicker ejecta containing high magnetic susceptibility exogenous metals there. This study not only helps to explain the mystery of magnetism in the lunar South Pole Aitken Basin, but also provides important ideas for future research on magnetic minerals and magnetic field evolution in samples from other celestial bodies such as asteroids and Mars. ”Pan Yongxin, academician of the Institute of Geology and Geophysics of the Chinese Academy of Sciences, said that this is very important for us to understand the history of the moon's magnetic field and the transformation process of the moon's surface. (New Society)