Chang'e 5 lunar samples are extremely precious, how to reduce the loss as much as possible——
New technology realizes simultaneous determination of lunar soil particle size and mineral composition
Science and Technology Daily (Reporter Wu Chunxin Correspondent Wang Junfang) How to reduce the loss as much as possible and test the particle size and mineral composition of the Chang'e 5 lunar soil samples?
On July 5, a reporter from Science and Technology Daily learned from China University of Geosciences (Wuhan) that the scientific research team of professors She Zhenbing and Wang Zaicong made new progress in the study of lunar soil. The team developed a new technology with extremely low sample consumption, which can simultaneously measure The grain 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 magma activity and space weathering process.
Relevant research results were published online simultaneously in both Chinese and English editions of the journal "Science China: Earth Science".
In July last year, a team led by Wang Zaicong, a professor at the School of Earth Sciences, applied for the first batch of lunar samples from 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 Zaicong introduced that since the 1970s, scientists have begun to use various methods to study lunar soil samples. , the methods used by the predecessors usually consume a lot of samples, and it is difficult to obtain various information such as mineral composition, particle size, and morphology at the same time.
Based on the Raman spectroscopic microparticle analysis technology, the research team developed a new method to simultaneously determine the particle size and mineral composition of the particle sample with extremely low sample loss, and successfully applied it to the study of the Chang'e-5 lunar soil sample.
The application of this research technique in the study of lunar soil is the first time in the world, and previous techniques can usually only carry out one of the studies of particle size or mineral composition.
According to reports, the study only requires about 30 micrograms of sample each time, which minimizes sample loss while obtaining multi-dimensional information, and the sample preparation is simple, which greatly reduces possible sample contamination problems.
In addition, this method can rapidly build a diverse information database of mineral grain size and composition in a short period of time, which is helpful for the discovery of rare mineral phases.
The further development of this method will provide key technical support for the rapid analysis of microparticle samples returned from other celestial bodies such as Mars and asteroids in the future.
The study found that the average particle size of the Chang'e-5 lunar soil samples was 3.5 microns, and the distribution was unimodal, indicating that it had a high maturity, that is, it was strongly weathered in 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 Zaicong said that the determination of lunar soil particle size plays an important role in the study of space weathering processes.
At the same time, the research team also built a monthly soil mineral spectrum database, analyzed the particles and automatically identified them, obtained information such as the particle size and volume of each mineral phase, and calculated the pattern abundance of minerals under different particle sizes.
The researchers found that the mineral composition in the 1 to 45 micron particle size range is: pyroxene, plagioclase, olivine, iron-titanium oxide, glass, and more.
The study also identified some trace mineral phases in the lunar soil, such as apatite, quartz, cristobalite and orthopyroxene, among which the discovery of orthopyroxene is the first report, which indicates that the Chang'e-5 lunar soil may contain Very small amount of lunar highland material.
The above results provide ground-truth information for the interpretation of spectral remote sensing data in the northern part of the Ocean of Storms in the Chang'e-5 landing area, and provide a new perspective for understanding the deep and surface evolution history of this region.