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- Title
Millimeter‐ to Decimeter‐Scale Surface Roughness of the Moon at the Chang'e‐4 Exploration Region.
- Authors
Guo, Dijun; Fa, Wenzhe; Wu, Bo; Li, Yuan; Liu, Yang
- Abstract
The 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 regions (∼20 m across) using the Digital Terrain Model (DTM) with a resolution of 5 mm/pixel. The bidirectional slope at the 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 synthesized the bidirectional slope at baseline from micrometer to kilometer, showing that bidirectional slope decreases from ∼60° at micrometer to ∼1° at a 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 data sets to radar and thermal observations, but also provide valuable information about lunar regolith characteristics, and small‐scale geological processes. Plain Language Summary: The roughness of a planetary body quantitively describes terrain surface topographic undulation at a horizontal scale and is widely used in geological and geomorphological studies. Roughness is an important parameter in radar observations due to its modulation of radar wave behaviors. Lunar surface roughness at a wide baseline range has been investigated before, but not in the baseline range of millimeter to decimeter. The Panoramic Camera onboard the Yutu‐2 rover collected millimeter‐scale resolution stereo images over China's Chang'e‐4 landing region. We generated a 5 mm/pixel resolution DTM covering an area of ∼20 m wide and then calculated three roughness parameters. We found that small impact craters, rocks, and regolith properties are the controlling factors affecting the millimeter‐scale roughness of the lunar surface. Combining with previous roughness results, we obtained lunar surface roughness versus baseline at scales ranging from micrometer to kilometer, which can be applied in a variety of studies. Key Points: We investigated millimeter to decimeter scale topographic roughness of the Moon in the Chang'e‐4 exploration region of ∼20 m wideThe median bidirectional slope is ∼10° at 7 mm scale and the median RMS height is ∼4 mm at 125 mm window size, and both show scale dependent behaviorsSmall impact craters, rocks, and regolith properties mainly affect millimeter‐scale topographic roughness of the Moon
- Subjects
CHINA; LUNAR craters; LUNAR surface; LUNAR exploration; SURFACE roughness; LUNAR soil; PANORAMIC cameras
- Publication
Geophysical Research Letters, 2021, Vol 48, Issue 19, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2021GL094931