How to reduce the loss as much as possible and test the particle size and mineral composition of chang'e-5 lunar soil samples? On July 5, the reporter of science and technology daily learned from China University of Geosciences (Wuhan) that the scientific research team of professors she Zhenbing and Wang zaichong of the university has made new progress in lunar soil research. The team has developed a new technology with extremely low sample consumption, which can simultaneously determine the particle size and mineral composition of lunar soil. This is of great significance for interpreting the remote sensing spectral data of the lunar deep space exploration orbit and understanding the lunar magmatism and space weathering process. The relevant research results were published online in the Chinese and English editions of the journal Science of China: geoscience. In July last year, the team led by Professor Wang zaichong of the school of earth sciences applied for the first batch of lunar samples of chang'e-5, a total of 200 mg. "The sample is very precious, and the allowable loss is only 50 mg. To produce more research results, we can only reduce the loss as much as possible." Wang zaichong said that since the 1970s, scientists have begun to use various means to study lunar soil samples. The methods used by predecessors usually require more samples, and it is difficult to obtain various information such as mineral composition, particle size and morphology at the same time. Based on Raman micro particle analysis technology, the research team developed a new method to simultaneously determine the particle size and mineral composition of particle samples with extremely low sample loss, which was successfully applied to the study of chang'e-5 lunar soil samples. The application of this research technology in lunar soil research is the first time in the world. In the past, only one of the particle size or mineral composition can be studied. According to reports, this study only needs about 30 micrograms of samples each time. While obtaining multi-dimensional information, the sample loss is minimized, and the sample preparation is simple, which greatly reduces the possible sample pollution problem. In addition, this method can quickly establish a diversified information database of mineral particle size and composition in a short time, which is conducive to the discovery of rare mineral facies. The further development of this method will provide key technical support for the rapid analysis of micro particle samples returned from Mars, asteroids and other celestial bodies in the future. The study found that the average particle size of chang'e-5 lunar soil samples was 3.5 microns, and showed a unimodal distribution, indicating that it had a high maturity, that is, it was strongly weathered by space. "Mineral particle size refers to the particle diameter. The average particle size of the finest flour exceeds 100 microns. The chang'e-5 lunar soil sample is dozens of times finer than flour." Wang zaichong said that the determination of the particle size of lunar soil plays an important role in studying the weathering process in space. At the same time, the research team also built a lunar soil mineral spectrum database to analyze particles and automatically identify them, obtain the particle size and volume of each mineral phase and other information, and calculate the pattern abundance of minerals under different particle sizes. Researchers found that the mineral composition in the particle size range of 1 to 45 μ m is pyroxene, plagioclase, olivine, iron titanium oxide, glass, etc. The study also identified some trace mineral phases in lunar soil, such as apatite, quartz, cristobalite and orthopyroxene. The discovery of orthopyroxene is the first report, which indicates that chang'e-5 lunar soil may contain a very small amount of lunar highland material. The above results provide a new perspective for interpreting the spectral remote sensing data of the northern storm ocean in the chang'e-5 landing area, providing ground live information, and understanding the deep and surface evolution history of the region. (Xinhua News Agency)