Science and Technology Daily reporter Jin Feng
The first lunar samples collected by Chang'e 5 can reveal the mysteries of the moon for us? This question has recently been partially answered. On December 13, the Purple Mountain Observatory of the Chinese Academy of Sciences released the news that a research result on the first lunar samples of Chang'e 5 was recently published online in the English edition of China's comprehensive academic journal Science Bulletin (Science Bulletin).
At 1:59 on December 17, 2020, the Chang'e-5 returner successfully returned to the ground with 1731 grams of lunar samples, realizing the sampling and return of extraterrestrial objects in China for the first time, and also bringing lunar samples back to the earth for the second time after 44 years, making China the third country in the world to retrieve samples from the moon.
High-resolution micro-CT images of Chang'e-5 basalt samples (CE5C0000YJYX065) at different angles and depths show typical sub-diabase structures, with olsite (Ol) in the form of spotted crystals and ilmenite (Ilm) distributed between the silicate minerals pyropene (Px) and feldspar (Pl) in fine needle-like particles. Photo courtesy of purple mountain observatory of the Chinese Academy of Sciences
The Purple Mountain Observatory of the Chinese Academy of Sciences is one of the first 13 scientific research institutions in China to obtain lunar scientific research samples, and researcher Xu Weibiao was approved two lunar basalt samples as the person responsible for use.
The research team conducted detailed mineralogical and three-dimensional tomography studies on one of the samples numbered CE5C0000YJX065 using high-resolution microCT, scanning electron microscopy, electron probes, etc.
Backscattered electron image of a particle of the Chang'e-5 basalt sample (CE5C0000YJYX065) (a) and its elemental plane scan (b), the main mineral pyroxene (Px) shows a pronounced chemical banding phenomenon, ilmenite (Ilm) appears in needle-like form, feldspar (Pl) exists in independent particles or is wrapped in pyroxene, and a small amount of ol (Ol) and silica (Silica). Photo courtesy of purple mountain observatory of the Chinese Academy of Sciences
The results showed that the sample belonged to the lunar volcanic basalt, with a fine-medium sub-diabase structure, a small amount of olivine porphyry distributed in a matrix composed of pyroxene, plagioclase, ilmenite and other by-minerals, and the chemical composition and evolution trend of the main constituent mineral pyridon were highly consistent with the high titanium basalt type returned by the American Apollo program and the Soviet Moon program.
The sample is known to contain an extremely high (17.8 vol% volume) ilmenite content, a richness close to the highest value of 18 vol of Apollo Basalt, and an enrichment of phosphate minerals (0.5 vol%).
(a) The variation trend of pyroxene composition in chang'e-5 basalt samples (CE5C0000YJYX065) and the comparison of (b)Fe/(Fe+Mg)-Ti/(Ti+Cr) projections with Apollo 11 and 17 high titanium lunar sea basalts (HT), low titanium lunar sea basalts (LT) and ultra-low titanium lunar sea basalts (VLT). Photo courtesy of purple mountain observatory of the Chinese Academy of Sciences
The researchers said that a number of evidence shows that unlike the recently reported types of titanium and low titanium lunar sea basalts in Chang'e 5, the sample is a relatively rare high titanium lunar sea basalt enriched with rare earth elements, which indicates that there may have been multiple volcanic eruptions in the history of the Chang'e 5 landing area, and it is expected to interpret the different material compositions in the source area of the lunar mantle, the energy source of volcanic magma formation and the fine spatio-temporal distribution of volcanic activity in the late lunar period, and follow-up deepening research work is underway.
Source: Science and Technology Daily