资源环境科技发展态势分析平台

Surface slope and roughness of the Moon have been investigated extensively over a wide baseline range except millimeter to decimeter scales. In this study, we present for the first time millimeter- to decimeter-scale surface slope and roughness of the Moon at China’s Chang’e-4 landing region (∼20 m across) using the Digital Terrain Model (DTM) with a resolution of 5 mm/pixel. The bidirectional slope at 7 mm scale can be larger than 40° with a median value of ∼10°. The root-mean-square (RMS) height within a window size of 125 mm varies from ∼1 mm to ∼18 mm with a median value of ∼4 mm. Both the bidirectional slope and RMS height show scale-dependent behaviors and the parameter of scale dependence, the Hurst exponent, is ∼0.6–0.85. We also synthetized the bidirectional slope at baseline from micrometer to kilometer, showing that bidirectional slope decreases from ∼60° at micrometer to ∼1° at kilometer. At millimeter-scale, surface roughness is mainly controlled by small impact craters, rocks and regolith properties. Our roughness results not only bridge the gap in understanding surface roughness from traditional topographic datasets to radar and thermal observations, but also provide valuable information about lunar regolith characteristics, and small-scale geological processes.