The Dielectric Properties of Martian Regolith at the Tianwen-1 Landing Site

Mars' surface is characterized by a weathered layer of regolith and exposed rock exposures that are the results of long-term geological processes. The Mars Rover Penetrating Radar (RoPeR) on board the Zhurong rover of China's first Mars mission (Tianwen-1) has been investigating the fine structure and dielectric properties of the martian regolith in the southern Utopia Planitia. The permittivity of the regolith within 5 m of the landing zone is 3.6(-2.0)(+3.1), and the average loss tangent is 0.0174(-0.0053)(+0.0053). The high lossy parameter suggests the possible cause for the missing subsurface reflectors in the landing region detected by either in-situ radar or orbiter radars. The permittivity distribution map has been derived to show permittivity varying with depth and location. The high dispersion of both permittivity and loss tangent values along the traverse path indicates relatively heterogeneous material distribution on the landing site compared to an airless body such as the Moon.