Subsurface Structure of Pockmarks Around the Zhurong Landing Site Revealed by RoPeR: Implication of the Final Water Activity
Ling Zhang, Xiangkai Fang, Yi Xu, Jiacheng Liu, Shaoping Lu, Zhijun Huo, Renrui Liu, Shuo Han, Chunyang Zhao, Xintong Dong, Rongzhe Zhang, Rui Chen, Xindong Meng, Xiaoping Zhang, Rui GaoAbstract
On 15 May 2021, China's Tianwen‐1 mission successfully delivered the Zhurong rover to southern Utopia Planitia. During sols 244–266, the rover identified a shallow pockmarked terrain and acquired subsurface structural data at its edge using the Rover Penetrating Radar (RoPeR). Analysis of the radar data reveals a distinct reflection interface at a depth of approximately 2–4 m, indicating physical differences between the ejected deposits and the original surface materials. The inverted dielectric permittivity ranges from 2.9 to 6.3, suggesting that the subsurface is dominated by dry, fine‐grained sediments rather than ice‐rich materials. Based on HiRISE imagery, we identified more than 50 pockmark‐like features and classified them into two morphological types: blocky and linear. Morphological analysis shows that these features are small‐scale, shallow depressions exhibiting significant orientation along the NEE–SWW and WNW–ESE directions, implying a structural control by regional stress fields. Integrating topographic, geomorphological, and radar‐derived evidence, we infer that these pockmarks most likely formed through the release of subsurface volatiles followed by surface collapse. This study reveals shallow geological processes in the Zhurong landing region possibly associated with late Amazonian water‐related volatile activity, providing new evidence for the recent surface evolution of Mars.