Shallow Water Ice Detection From SHARAD Data in Central Utopia Planitia, Mars

Abstract

One of the key scientific goals of China's first Mars mission Tianwen-1 is to search for ground ice. This study focuses on investigating potential water ice reservoirs in the vicinity of the landing site of the Zhurong rover to provide geological context and references for data interpretation. Our study area is centered on Utopia Planitia (UP), where Shallow Radar onboard the Mars Reconnaissance Orbiter (SHARAD) previously detected subsurface echoes that could be interpreted as ice deposits. Based on the SHARAD data, we have estimated the thickness, dielectric properties, and possible material composition of the surface deposition layer. The inferred water ice volume content ranges from approximately 55%–85%, which is consistent with deposits found on the western edge of UP. Based on morphological features and radar data products, we interpret the detected sediment layer as the latitude-dependent mantle (LDM). We have conducted a comprehensive analysis of the distribution and morphology of various periglacial landforms, including Decameter-scale Rimmed Depressions (DRDs), polygonal landforms, and scalloped depressions on the surface of UP. The implications for the level of degradation are discussed. The radar results provide evidence that DRDs have formed as a result of the degradation of the LDM layer. Additionally, our statistical analysis of concentric crater humps (CCH) linked to subsurface pure glacial ice suggests the possible presence of an icy layer that may be as thick as a kilometer beneath the LDM unit.