Detection of water-ice deposits using synthetic aperture radar (SAR) is a cost-effective, and efficient approach to understand lunar water resources. As water is crucial to supporting human-based space exploration, current and near upcoming lunar missions are primary concentrated on mapping and quantification of water ice exposures on surface and subsurface levels. The circular polarization ratio greater than one (CPR >1) derived using the orbital radar observations is considered as an important SAR derived parameter for water-ice detection. This study aims to investigate 14 craters near the lunar poles with high CPR (CPR >1), as identified in previous studies, using the L-band (24 cm) dual frequency synthetic aperture radar (DFSAR) onboard Chandrayaan-2. In addition to CPR, we computed the degree of polarization (DOP) after applying parallax error correction that helps in reducing misinterpretation. Our findings are based on orthorectified DFSAR calibrated data analysis. We found that the CPR of crater interiors is not significantly different from that of their surroundings, and this pattern is consistent throughout all the 14 craters selected. Further, we also found a linear inverse relationship between CPR and DOP for the interior and exteriors of the craters, with R-2 0.99, indicating a strong correlation between these two parameters. We found only 2 % of total pixels are above CPR > 1, which indicates that there is less possibility of homogeneous water-ice but the possibility of water-ice mixed with the subsurface regolith cannot be ruled out.

Scientific explorations have shown that the lunar water-ice exists only in the bottom of craters of lunar South and North pole, where is permanently dark and as cold as 40K This paper presents the concept of increase the temperature of water-ice by reflecting the sunlight to a certain area using polar orbit satellite formation, such that the water-ice is more detectable. The orbit of spacecraft is designed and the expected attitude is derived based on the relative motion between the spacecraft and the water-ice. The objective is to keep the reflected light from spacecraft point to the water-ice during the process so that the water-ice can be heated by solar radiation. A nonlinear adaptive controller is developed. Numerical simulations demonstrate the effectiveness of the control algorithm.