Fig. 2: Dielectric constant estimation, loss tangent estimation, and subsurface images at the CE-6 landing site based on LRPR data.

a Histogram of the permittivity estimations using CE-6 and CE-5 LRPR datasets. The red bars show the results (\({\epsilon }_{r}=2.22\pm 0.72\)) from the CE-6 LRPR, and the blue ones represent the CE-5 LRPR results (\({\epsilon }_{r}=2.48\pm 0.79\)). b Loss tangent estimation using the central frequency decay method. The black dashed line indicates the fast time-dependent decay of the central frequency in the single-trace data from the CE-6 LRPR. The red solid line represents the best fit across all data (\(\tan \delta =0.010\pm 0.002\)), and the red dashed lines shows the upper bound and lower bounds of the estimation. The blue curve represents the averaged central frequency decay from all observations. c Pictorial image of subsurface structure at CE-6 landing and sampling site. The illustration emphasizes the rock size distribution based on the CE-6 LRPR image shown in (d). The rocks are represented by the shapes filled with solid color. The gray background represents fine-grained regolith and the brown background represents coarse regolith. d LRPR image from the CE-6 mission (Data ID: CE6-L_GRAS_LRPR-A_SCI_N_20240602012333_20240602014101_0001.01). The red regions indicate areas of high reflectivity, while the blue regions indicate areas with low reflectivity. The horizontal axis is centered at the drill position, and the vertical axis represents the depth. (e) LRPR image from the CE-5 mission for comparison (Data ID: CE5-L_GRAS_LRPR-A_SCI_N_20201201171559_20201201173326_0001.01).