Martian regolith structure at Tianwen-1 landing zone revealed by Full-polarimetric Mars rover penetrating radar data

This study reports the results of full-polarimetric Mars Rover Penetrating Radar (RoPeR) data acquired by China’s Tianwen-1 mission. A double-layered regolith structure within a depth of 3 m is revealed which are different in scattering features, structure, and maturity. Five types of dense rocks are identified at the surface and subsurface. Three types of these dense rocks are residual materials of native craters. Besides, the dense rocks on the Martian surface are isolated boulders delivered by adjacent impacting or windblown events. The dense rocks within the first stratum have smooth surfaces and great loss tangents, which are similar to the platy duricrusts observed on the Martian surface formed by aqueous activities. Overall, the observed Martian regolith structure is strongly heterogeneous and aqueous activities may have important contributions to it. The aqueous activities within the Martian regolith may be more active than is inferred according to the observations on the surface.