China Focus: Chinese scientists refine lunar global chemistry mapping using farside ground truth information

BEIJING, March 10 (Xinhua) -- A team of Chinese scientists has unveiled a high-resolution atlas detailing the global distribution of lunar surface chemistry, a significant advance that fills a critical data gap in the geological study of the moon's far side.

Mapping the chemistry across the lunar global surface is essential for understanding the moon's magmatic evolution and geological history, and holds profound implications for studying the Earth-moon system.

Previous estimates of elemental abundances relied primarily on remote sensing data calibrated with sample-based ground truth information from the lunar nearside, according to a recent research article published in the journal Nature Sensors. This left the far side of the moon largely unconstrained, introducing substantial uncertainties in geological models for terrains with complex compositions, especially within the scientifically vital South Pole-Aitken (SPA) basin.

To overcome this long-standing challenge, the research team, led by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, developed an intelligent inversion framework for lunar chemical components leveraging a residual convolutional neural network, on the basis of farside ground truth data from the samples taken back by the Chang'e-6 mission and combining high-resolution visible-to-near-infrared multispectral-band image data from the lunar orbiter.

By employing a model-fine-tuning strategy to optimally calibrate elemental abundances, the team generated high-precision global maps of major elemental oxides that incorporate farside ground truth information.

This breakthrough successfully constrains the extent and composition of farside terranes and precisely reveals deep-seated materials exposed within the SPA basin and highlands.

The maps quantitatively demonstrate that the proportion of exposed magnesian anorthosite in the farside highlands is significantly higher than on the nearside. This provides new measured evidence supporting the hypothesis of asymmetric crystallization and differentiation of the lunar magma ocean between the two hemispheres.

By integrating farside ground truth information into global geochemical mapping, this study deepens the understanding of crust-mantle structure, hemispherical evolutionary differences, and the formation and evolution of the SPA basin.

It provides high-precision, quantitative guidance for future landing site selection, resource exploration, and the planning of lunar exploration missions.

The Chang'e-6 probe was launched by China on May 3, 2024. On June 25, 2024, its returner landed in north China, bringing back 1,935.3 grams of samples from the far side of the moon. ■