Bistatic Radar Investigation of Water Ice Deposits in the Lunar Polar Regions

Deep space bistatic radar measurements face several challenges in planetary exploration, including rapidly varying observation geometry, extremely low signal-to-noise ratios, and difficulties in calibrating channel gain and phase due to the absence of onboard calibration sources. To address these issues, this study develops a bistatic radar terrain inversion system tailored for deep space applications. Using the SPICE （Spacecraft Planet Instrument C-matrix Events） toolkit and focusing on echo data acquired under near-backscatter conditions, the system integrates geometry modeling, data calibration, and multiparameter inversion of surface characteristics. The analysis demonstrates that the proposed system successfully extracts electromagnetic indicators associated with potential water-ice deposits in the lunar south polar region, including enhanced echo power, locally elevated circular polarization ratios （CPR）, reduced dielectric constants, and disturbed cross-spectrum phase behavior. These combined features support the possible presence of polar water-ice deposits. The results further verify the effectiveness of deep space bistatic radar for surface and material inversion and provide a scalable technical pathway for future bistatic radar applications in deep space missions.