Deriving terrain factors from high-resolution lunar images: A case study of the Mons Rumker Region

Mons Rumker is a preferred candidate landing region for China's Chang'e-5 (CE-5) mission, from where it is of great significance to select safe landing areas. Lunar terrain factors fromDigital ElevationModel (DEM) data, limited by their lowresolutions (similar to 10 m/pixel), are inapplicable to evaluating the lunar landing area safety, in spite of the fact that lunar remote sensing imagery has higher resolution (similar to 50 cm/pixel). In this paper, we extracted terrain factors in divided square girds by the aid of the high-resolution Lunar Reconnaissance Orbiter (LRO) Narrow-angle Camera (NAC) images, namely, flat area percentage (Fap), distribution pattern of uneven objects (NNI) based on the double-threshold Otsu method, and roughness based on gray level histogram analysis. Mons Rumker can be divided into four geological units, named as LD, B1, B2, and B3, respectively. Unit B1 has a higher roughness and a lower Fap. Unit B2 and B3 are characterizedwith the highest Fap and the lowest roughness. NNIs of Unit B1, B2, and B3 are N1while LD's is <1. Thus, the distribution patterns of uneven objects in Unit LD are clustered but dispersed in all Unit B1, B2, and B3. This paper tends to take Fap and roughness as the main terrain factors to evaluate the safety for CE-5 landing in Mons Rumker with NNI being a supplement to Fap. According to Standard 1-3 mentioned in this paper, we would classify the divided square grids of the Mons Rumker region as the safe or unsafe areas, and then discriminate five potential landing areas for CE-5 probe safe landing. (C) 2020 Elsevier B.V. All rights reserved.