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$5~\sim ~8$-m regolith,$2~\sim ~3$-m fine materials, and$15~\sim ~30$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.

This work presents the results of the Lunar Regolith Penetrating Radar (LRPR), installed at the bottom of the Chang’E-5 (CE-5) lander, which is the first antenna-array radar deployed for the investigation of an extraterrestrial body. Radar imaging results unveiled a hyperfine structure for the top 2.5-m-thick lunar regolith with an unprecedented high resolution of 5 cm. The interpretation of the results permitted to state that subsurface regolith is dominated by fine grains with abundant rock fragments. The radar imaging results were also used to drive the drilling process until a fragment jammed the core inlet at about 100-cm underground. Laboratory measurements of the samples returned at Earth allow to estimate the real part of relative permittivity and the loss tangent, which are 3.04 ± 0.02 and 0.014 ± 0.002, respectively.

The Chang’E-2 (CE2) lunar orbiter was the second robotic orbiter of the Chinese Lunar Exploration Program, as well as the pioneer robotic orbiter in the soft landing project in the second phase of the program. It used a two-line stereo camera to acquire stereo images with global coverage at a resolution of 7 m. The stereo images have a large potential for producing the best lunar topographic map. However, errors and uncertainties in the interior orientation (IO) and exterior orientation (EO) parameters of the camera seriously affected the accuracy of the global topographic mapping. In this paper, a global adjustment method is proposed to eliminate the effects of these errors. The error models are represented by a Chebyshev polynomial. The polynomial coefficients were estimated as unknowns using five lunar laser ranging retroreflector (LRRR) points as ground control points in the adjustment. The experimental results show that the planimetric and height deviations between the neighboring strips were 5 and 2 m (less than 1 pixel), respectively, which were decreased by 32.6 and 31.5 times, respectively, relative to those derived from the original EO parameters. The large inconsistencies in the CE2 trajectory data were significantly reduced after the adjustment. In comparison with the LRRR positions, the planimetric and height errors ranged from 21 to 97 m and −19 to 10 m, respectively. A new seamless mosaic and high precision absolute position topographic map has been generated using this method.