Comparison of the Surface Morphology of the Floors of Craters near the Pole and at Mid-Latitudes of the Moon

Abstract

The surface morphology of the permanently shadowed floors of near-polar craters Faustini, Shoemaker, and Haworth and the regularly illuminated floors of craters Macrobius and Boss was studied on the basis of the photogeologic analysis of images acquired with the ShadowCam onboard the Korea Pathfinder Lunar Orbiter and the Narrow Angle Cameras of the Lunar Reconnaissance Orbiter (LROC NAC), as well as with the use of the Lunar Orbiter Laser Altimeter (LOLA) measurement data. It has been shown that craters with diameters from tens to hundreds of meters dominate the surface morphology of the floors of all five craters studied. On the inner slopes of the craters, both shadowed in near-polar craters and regularly illuminated in nonpolar craters, an undulating surface texture resembling an elephant hide is observed. On the floors of craters Macrobius and Boss, there are gently sloping hills, while such hills are absent on the floors of craters Faustini, Shoemaker, and Haworth; i.e., the floors of the studied near-polar craters are flatter on the scale of a few kilometers. On the floors of near-polar craters, craters with lobate rims are observed. Formation of these rims are apparently connected with the presence of H₂O ice in the target material. Craters of this kind represent only a few percent of the total number of craters considered. They are located in different places of the studied areas and differ in size, which apparently suggests that water ice in the target material is unevenly distributed over the area and depth of occurrence. On the floors of craters Macrobius and Boss, there are rare craters, which somewhat resemble the lobate morphology. This observation requires further study.