Investigating Martian Subsurface Features in Utopia Planitia With Tianwen-1 Ground-Penetrating Radar

This article deals with the investigation of the Martian subsurface in the Utopia Planitia region using Zhurong’s ground-penetrating radar. The low-frequency data recorded along the overall path followed by the rover are processed thanks to a customized signal processing pipeline aiming on one side to minimize the artifacts in the radargrams and, on the other one, to obtain images of the subsoil that aid the following analysis and interpretation stage. The images reveal a three-layer structure beneath the landing area up to the depth of ~40 m. The general scattering characteristics indicate the presence of <inline-formula> <tex-math notation="LaTeX">$5~\sim ~8$ </tex-math></inline-formula>-m regolith, <inline-formula> <tex-math notation="LaTeX">$2~\sim ~3$ </tex-math></inline-formula>-m fine materials, and <inline-formula> <tex-math notation="LaTeX">$15~\sim ~30$ </tex-math></inline-formula> m embedded with blocks generating a significant electromagnetic scattering. The existence of an upward decrease in grain size is resulted from long-term weathering and repeated impacts or the occurrence of flood events. The radargrams depict a distinctive local enhancement of the scattering at the end of the rover route from Sol 292 to Sol 325. Analysis of the layout of barchan dunes and the distribution of craters suggests that the resurfacing activity is the result of a complex combination of tectonic activities and impact events.