Landing Site Selection and Characterization of Tianwen-1 (Zhurong Rover) on Mars

The Chinese Mars rover Zhurong onboard the Tianwen-1 probe successfully landed on Mars in May 2021. Here, we report our efforts in selecting a landing site for Zhurong within a pre-identified landing region in southern Utopia Planitia. Using the high-resolution images collected by a camera onboard the Tianwen-1 orbiter, the landing region was analyzed in detail in terms of surface slopes, crater densities and rock abundances, which enabled the optimized determination of a landing ellipse (56 x 22 km for the major and minor axes) with minimum hazards and assisted the successful landing of the Zhurong rover. We also characterized the landing site and region after landing. Surface images captured by a camera onboard the Zhurong rover revealed a low rock abundance of approximately 4% at the landing site, similar to the rock measurements from orbital data before landing. Images of the surface features and a hole excavated by the pulsed retrorockets beneath the lander suggested a shallow regolith structure with a surficial layer of dust and sand over a layer of duricrust, and brecciated/fragmented rocks and bedrocks beneath. Crater size-frequency distribution analysis indicated that the landing region might have experienced multiple episodes of resurfacing.