Lunar Surface Imaging Polarimetry: II. Mare Fecunditatis and Messier

Abstract

Telescopic analysis of the Moon with imaging polarimetry characterizes the lunar surface by its albedo, its grain size, and its roughness. The technique was explained in a Paper I (Dollfus, A., 1998, Icarus136, 69–103) and is summarized in the Introduction.Images are produced at different phase angles for the light flux (images I), for the degree of linear polarization (images P), for the linearly polarized flux (images Q), and for the linear flux corrected from albedo (images Q0). Their analysis describes the lunar terrain roughness by the mean slope angle θ of the facets of all sizes integrated and the grain size by the median value Md of the size distribution. Special results are obtained from observation under specular conditions of illumination.In this Paper II, an area around Crater Messier on Mare Fecunditatis is analyzed. Compared with “mature” mare surfaces, highlands appear rougher and made of larger grains. Rays ejected around Messier are still larger grained (“submature” surfaces). Mare Fecunditatis is mantled by a sheet of fragments of crustal composition ejected up by the impact which created crater Taruntius, 200 km apart. Small dark patches are also observed.A vertical section of the lunar terrains was derived from the imaging polarimetry results. This section cuts from Crater Messier to the highland westward.