Microwave tomography for Lunar Penetrating Radar data processing in Chang'e 4 mission.

This work presents the results achieved by applying a microwave tomographic approach to the data collected by the Lunar Penetrating Radar onboard Yutu-2 rover in the frame of the Chang'e 4 mission. The adopted signal processing pipeline comprises two steps: the first one is a pre-processing stage involving time-domain procedures required to filter the clutter and noise on raw data; the second step regards the exploitation of a microwave tomographic approach designed to tackle the computational issue imposed by the large (in terms of probing wavelength) domain investigated by the rover. Two tomographic approaches, different for modeling the signal propagation through the air-soil interface, are considered and compared. The results are provided as tomographic images along the route of 1340 m; the tomographic images confirm the presence of interesting subsurface geometrical features, whose geological interpretation agrees with the studies presented in previous papers.