Dual-Frequency Radar Sounder Correlation Measurements For Surface Roughness Mapping

Planetary radar sounders provide information that helps to characterize the surface and subsurface of planetary bodies, providing insights into their structure, composition, and topography. Surface roughness is one of the main interesting variables that can be estimated by radar sounder data. In this work, we propose a technique for generating surface roughness maps with an imaging technique applied to dual-frequency radar sounder data. The method projects the radar echoes onto a digital elevation model (DEM) and combines simultaneous acquisitions at two frequency bands. Exploiting the omnidirectional nature of dipole antennas, we integrate signals from multiple range lines and orbit tracks to resolve ambiguities in the direction of arrival. The result is a cross-correlation metric derived from projections of dual-frequency acquisitions, representing the probed surface roughness. We demonstrated this approach using MARSIS multifrequency radar sounder data acquired over Mars. In particular, we generated a roughness map of the Olympia Undae region. The method confirmed its effectiveness as it is correlated with other Martian surface roughness maps and presents a sensibility of 50∼100 m-scale roughness features.