Characterization Of The Candidate Landing Region For Tianwen-1-China'S First Mission To Mars

This paper presents our efforts to characterize the candidate landing region (109 degrees-133 degrees E, 23 degrees-30 degrees 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 degrees. 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.