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This paper presents our efforts to characterize the candidate landing region (109°–133°E, 23°–30°N) for Tianwen‐1, China's first mission to Mars, in terms of engineering safety and scientific significance. Topographic analysis reveals that the region has a low elevation around −4,230 m, and 98% of the region have slopes smaller than 8°. The geomorphological mapping and analysis show that the region has an average crater density of about 28 craters (≥200 m in diameter) per 100 square kilometers, with several clusters of high crater densities distributed around the center of the region. There are also pitted cones distributed mainly in the southern part of the region, with a density of approximately 6.6 cones per 100 square kilometers in specific local areas. The region has rock abundances ranging from 1% to 23%, with local clusters of low and high rock abundances. The region comprises four main geological units, including a lowland unit formed in the Late Hesperian and a volcanic unit formed in the Amazonian and Hesperian period. Their specific surface ages are estimated through the analysis of crater size‐frequency distribution. Combining the engineering constraints on surface slopes, crater density, cone density, and rock abundance, a hazard map of the candidate landing region is generated for landing site evaluation and safety assessment. Based on the results, we further discuss the potential scientific outcomes from the exploration in this region. The findings will be helpful for the mission planning and maximization of the scientific return from Tianwen‐1, and complement existing Martian scientific research. Key Points: Topographic, geomorphological, and geologic characterization of the candidate landing region of Tianwen‐1A hazard map of the region combining engineering constraints on slopes, crater density, cone density, and rock abundanceTwo local areas in the region are highlighted as potential landing sites for their low hazard and scientific significance [ABSTRACT FROM AUTHOR]

The morphology of impact craters on the Moon is important for understanding impact cratering process and lunar surface properties. Though the morphology of lunar impact craters at hectometer scales and larger is extensively investigated and well understood, the morphology of very small craters is rarely studied due to the lack of high‐resolution data. In this study, we investigated the morphology of 1,513 craters at decimeter to hectometer scales using the 5 mm/pixel–0.5 m/pixel topographic data of the Chang'E‐3/4/5 (CE‐3/4/5) landing regions. Our results show that crater depth, rim height, and inner wall slope increase with the diameter and that the mean values of depth/diameter ratio, rim height/diameter ratio, and inner wall slope are 0.065, 0.017, and 10.5°, respectively. These morphometric parameters are smaller than those of large craters above hectometer scales, which is probably due to low‐strength surficial regolith and rapid topographic degradation. The comparison of the morphometric parameters among the three regions suggests that the CE‐4, CE‐3, and CE‐5 landing regions have the highest, intermediate, and lowest regolith strengths, respectively. In addition, we first observed widespread meter‐scale concentric and flat‐bottomed craters in optical images, which are most probably formed due to strength heterogeneity within the regolith layer. Our results can help to understand near‐surface properties of the regolith layer, lunar surface evolution, and impact cratering process in the strength regime. Plain Language Summary: Crater morphology plays an important role in understanding the surface property of a planetary body. On the Moon's surface, the morphologies of impact craters upon the formation are related to surface structure and physical properties at different depths, and through time, the morphologies change because of subsequent modification and weathering processes. With the high‐resolution topographic data and optical images from China's Chang'E‐3/4/5 missions, the morphometry of very small craters below hectometer scales can be accurately extracted, which can provide essential information for physical properties of the regolith layer. In this study, we investigated the morphology of craters at decimeter to hectometer scales in the Chang'E‐3/4/5 landing regions. We found that the morphometry of very small craters is mainly influenced by a combined effect of the low‐strength surficial regolith layer and the relatively fast topographic degradation rate. We first observed widespread meter‐scale concentric and flat‐bottomed craters and further proposed two possible mechanisms for their formation. Our results are helpful in understanding the structure and properties of the regolith layer, the evolution of the lunar surface, and impact cratering process dominated by target strength. Key Points: Morphological characteristics of decimeter‐ to hectometer‐scale impact craters at the Chang'E‐3/4/5 landing regions are investigatedRegolith property and topographic degradation are the two major factors affecting the morphology of very small cratersWidespread meter‐scale concentric and flat‐bottomed craters are first observed in optical images [ABSTRACT FROM AUTHOR]