Exploring the dielectric loss of Martian regolith in the frequency domain using Zhurong radar data

Martian regolith is one of the primary science objectives of Mars exploration missions. The Rover Penetrating Radar carried by Zhurong rover allows for high-resolution subsurface imaging and in-situ measurements of Martian regolith dielectric properties, which are crucial to advance our understanding of Martian geology and hydrological evolution. While earlier studies have derived dielectric constants for the shallow subsurface, further characterization of subsurface materials requires the determination of attenuation properties. In this study, we applied the centroid-frequency shift method to explore the attenuation property of the Martian regolith in the frequency domain. Lateral attenuation variation was analyzed in detail by integrating subsurface radargram and navigation terrain images. The results show that, within a depth of ∼4 m, the attenuation of radar signal for Zhurong subsurface material is equal to a loss tangent of 0.0079, with a standard deviation of 0.001. Based on the loss tangent value, dielectric permittivity and ground characterization, we preclude the possibility that the regolith is predominantly igneous materials. The lateral variation of the attenuation property could likely be attributed to changes in the proportion of duricrusts, which are heterogeneously distributed along the rover traverse. Our findings offer valuable information for understanding the Martian regolith and its evolution, serving as a important reference for future Mars sample return missions.