Radar Images of Permanently Shadowed Regions at the South Pole of the Moon
Астрономический вестник, Vol. 58, Iss. 4 (2024)
Keywords: Moon, south polar region, permanently shadowed regions, radar images, radar scattering, circular polarization ratio
Abstract
The paper presents new detailed radar maps and polarimetric data covering the southern polar region of the near side of the Moon measuring 400 × 800 km with a spatial resolution of about 75 m. The data were obtained using the 64-meter antenna (TNA-1500) of the Satellite Communications Center Bear Lakes of the Special Design Bureau of the Moscow Power Engineering Institute and the 13.2-meter radio telescope (RT-13) of the Svetloe Observatory of the Institute of Applied Astronomy, Russian Academy of Sciences, at a wavelength of 4.2 cm. At this wavelength, radar signals penetrate the lunar regolith to depths of up to 1 m and are sensitive to surface and suspended rocks larger than 1 cm. The maps show 39% of the area of permanently shadowed regions not observable by optical Earth-based instruments, which may hide water ice deposits. Analysis of radar maps did not reveal any relationship between the polarization properties of the surface in these regions and the presence of solar illumination. The data obtained as a result of this work can be used to study the surface and subsurface regolith features of the lunar south polar region, including searching for ice deposits in permanently shadowed regions, as well as for planning future lunar missions.