Bistatic Radar Detection of Water Ice Deposits in Lunar Polar Regions

Deep space bistatic radar facing some challenges in planetary exploration, including rapidly varying observation geometry, extremely low signal-to-noise ratios, and difficulty in calibrating channel gain and phase due to the absence of onboard calibration sources. To address these issues, a bistatic radar terrain inversion system tailored for deep space applications was developed. Using the SPICE （Spacecraft Planet Instrument C-matrix Events） toolkit and focusing on echo data acquired under near-backscatter conditions. The system integratd geometry modeling, data calibration, and multiparameter inversion of surface characteristics. The analysis demonstrates that the proposed system successfully extracted 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 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.