KevinJamesNg

Traveling through time and space & Doing timey wimy stuff.

More than One year ago on 24th November 2020, the Chang Zheng – Long March Five Carrier Rocket Launched away  in CNSA – China National Space Administration China Wenchang spaceport launch, Change Five  Lunar probe into orbit, opened up towards China – People’s Republic of China’s first celestial bodies sample return trip from Mons Rumker on the Lunar Surface of the moon New research achievements – Chinese scientists reveal the composition of lunar soil minerals and space wind at the landing site of Chang’e 5

China – People’s Republic of China’s first lunar sampling return mission, Chang’e-5 (CE-5), landed on the young KREEP terrane Mons Rumker in the northern part of the Ocean of Storms, and successfully brought back 1731 grams of lunar soil.

 Predecessors have used orbital remote sensing data to conduct extensive research on the topography and material composition of the CE-5 landing area. Recently, a series of sample analyses have advanced the understanding of lunar chronology, late lunar volcanism, and magma evolution mechanisms. Different from large-scale remote sensing observation and fine sample analysis, in situ spectral detection can not only provide local background information of the sampling area, but also be beneficial to study the characteristics of lunar soil in undisturbed and disturbed states. The Lunar Mineral Spectrometer (LMS) carried by the CE-5 lander acquired the visible-infrared reflectance spectrum of the lunar soil, which provided important data support for the study of the material composition of the lunar soil and space weathering.

Researchers from the Key Laboratory of Solar Activity and Space Weather of the National Space Science Center of the Chinese Academy of Sciences (hereinafter referred to as the “Space Center”) used the Chang’e-5 LMS in situ detection data to analyse the material composition and maturity, spectral parameters and unmixing of the lunar soil at the landing site The study shows that the mafic minerals in the lunar soil are mainly clinopyroxene, which is consistent with the chemical analysis and orbital spectral analysis results of the CE-5 sample in the laboratory.

The optical maturity and submicroscopic iron (SMFe) of the lunar soil did not change significantly before and after the rocket purge and shovel sampling. This study provides spectral evidence that the lunar soil surface experienced rapid tillage and adequate mixing.

Figure 1: (A) The measured field of view of the LMS spectral data is shown in the red box. Panoramic cameras show images of (B) lunar soil and (C) rocks, respectively. (D) LMS reflectance spectrum curve.

The red box in Figure 1A shows the observation field of LMS spectral data, where D11 is the rock block, and D14-D16 are the lunar soil spectra after shovelling. The magnified images of lunar soil and rocks are shown in Figure 1B and C, and Figure 1D shows the reflectance spectrum curve after preprocessing such as radiometric calibration and thermal correction.

Through the spectral parameter map of the absorption features at 1 μm and 2 μm (Fig. 2A), it was found that with the increase of calcium content, the absorption positions of pyroxene at 1 μm and 2 μm moved to the long-wave direction, and the lunar soil and rocks at the CE-5 landing site For high-calcium pyroxene, this is further confirmed in the 1 μm absorption center and the ratio projection of the 2 μm to 1 μm absorption area (Fig. 2B).

In this study, the Hapke model and the sparse unmixing algorithm were used to invert the mineral composition and abundance of the in situ spectra. The inversion results were consistent with the analysis results of CE-5 samples and the inversion results of orbital remote sensing (Fig.

Figure 2: LMS in situ spectral composition analysis

Space weathering is a common phenomenon of spectral reddening and darkening caused by micrometeorite impacts and solar wind injection on non-atmospheric celestial bodies.

First, the maturity of the lunar soil at the CE-5 landing site was qualitatively analyzed by using the projection maps of the spectral slopes R950/R750 and R1600/R700 and R750 and R700 respectively (Fig. 3A, B). It was found that compared with the lunar soil at the CE-4 landing site, the The lunar soil in the CE-3 and CE-5 landing areas is relatively immature, which may be related to the fact that CE-3 and CE-5 landed on a young impact crater sputter carpet (<100 Ma).

This study further calculated the optical maturity (OMAT, Fig. 3C) and submicroscopic iron (SMFe, Fig. 3D) content, and found that there was no significant change in lunar soil maturity before and after the rocket purge, and before and after scooping, indicating CE-5 landing The lunar soil in the district has experienced an equivalent exposure history within the scooping depth (<3cm).

This result is consistent with the radionuclide analysis results of the Apollo drilling samples and the simulation results of the lunar soil tillage model. This study provides spectroscopic evidence that the lunar soil surface undergoes rapid tillage and adequate mixing.

Figure 3: LMS In Situ Spectral Maturity Analysis

Space weathering is a common phenomenon of spectral reddening and darkening caused by micrometeorite impacts and solar wind injection on non-atmospheric celestial bodies.

First, the maturity of the lunar soil at the CE-5 landing site was qualitatively analyzed by using the projection maps of the spectral slopes R950/R750 and R1600/R700 and R750 and R700 respectively (Fig. 3A, B). It was found that compared with the lunar soil at the CE-4 landing site, the The lunar soil in the CE-3 and CE-5 landing areas is relatively immature, which may be related to the fact that CE-3 and CE-5 landed on a young impact crater sputter carpet (<100 Ma).

This study further calculated the optical maturity (OMAT, Fig. 3C) and submicroscopic iron (SMFe, Fig. 3D) content, and found that there was no significant change in lunar soil maturity before and after the rocket purge, and before and after scooping, indicating CE-5 landing The lunar soil in the district has experienced an equivalent exposure history within the scooping depth (<3cm).

This result is consistent with the radionuclide analysis results of the Apollo drilling samples and the simulation results of the lunar soil tillage model. This study provides spectroscopic evidence that the lunar soil surface undergoes rapid tillage and adequate mixing.

上述研究成果

已成功发表于国际权威学术期刊

Earth and Planetary Science Letters上。

Via CNSA China Space Administration –CLEP China Lunar Exploration project management office

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