Three-Layer Radar Sounder Model for the Detection of Buried Ice Deposits Under Martian Regolith

In this paper, a three-layered electromagnetic backscattering sounder model based on the Kirchhoff Approximation is developed for P-band and L-band frequencies. The backscattered power is calculated by a scalar approach, where polarization is not considered. To account for the along track resolution by Synthetic Aperture Radar (SAR) processing and the beamwidth, a Gaussian function is applied to bound the illuminated area. The model is used to evaluate the ice-detection measurement performance of the L-band sounder radar for the planned International Mars Ice Mapper (I-MIM) mission. A regolith layer with embedded volume scatterers and an underlying ice layer are assumed in this model. Loss tangent and dielectric permittivity of a Martian regolith layer are extracted from data acquired from MARSIS mission, SHARAD mission, Mars rover missions and laboratory measurements. Size and fractional volume of the regolith scatterer, along with roughness of a regolith layer and buried ice layer were varied to determine their effect on detectability of backscatter from a regolith-ice interface. The effects of loss tangent and surface roughness of the Martian regolith on the radar signal show that the ice detection depth can reach up to around 16 m in favorable cases or drop off below 0.5 m when the roughness is large. These results have important implications for future radar instrument design and targeting plans for I-MIM and future radar missions to Mars.