SHARAD-Based Detection and Estimation of Water-Ice Content in Korolev Crater at the North Pole of Mars

The quest for water-ice is critical in the scientific exploration of Mars, as areas where water reservoirs have been identified could be attractive landing sites for future missions. Korolev crater is located at the Martian north pole, and the interior of the crater is known for its distinct layer of bright deposits exposed at the surface, probably composed of water-ice and rocks. Although studies have estimated the depth of the deposits, the effective volume of ice remains undisclosed. We quantified the volume of water-ice within Korolev crater using the Shallow Radar (SHARAD) data, supported by the global MOLA DEM and Context Camera imagery. We applied MOLA data to simulate clutter for 69 SHARAD tracks and improved the identification of radar surface echoes and subsurface reflections. Further, we extracted 18 tracks with discernible surface and subsurface echoes to calculate the dielectric constant for mapping the depth of the ice cover. Spatial visualization was accomplished by superimposing the dielectric constant map onto Korolev crater's 3D topography, unveiling a trend from north to south, with values of the constant dropping from 4.42 to 2.84. The dielectric constant's least-squares solution of 3.565 corresponds to a water-ice content in the range of 50%-88.5%, depending on an unknown portion of rock and porosity of the material, confirming earlier inversion results of SHARAD data. Our method presents a viable approach for Martian water-ice detection and contributes insights into the subsurface water-ice deposits and its dielectric constants. These findings offer critical scientific data to support forthcoming exploration missions (e.g., China's Tianwen-3).