Lunar Surface Imaging Polarimetry. III. Langrenus

Abstract

The program of lunar surface texture analysis conducted with polarimetry at Observatoire de Paris included crater Langrenus. The area was analyzed with the video-polarimeter in terms of albedo, surface roughness, and grain size. An image was produced, mapping the terrain roughness at the surface of the Moon (parameter θ), and another image mapped the median grain size (parameter Md). It is when making these observations that transient bright features were discovered near the crater central peak. They will be analyzed specifically in another paper. The Langrenus floor around the area on which the brightenings occurred is characterized as very rugged terrain at centimeter to meter scale, mantled with a layer made of high-albedo grains of large median size. The ejecta blanket deposited around Langrenus has disymetric textural properties, suggesting that the crater was formed by an oblique impact. A recent impact in the northern part of this aureole excavated the basaltic material beneath the layer and projected onto the surface a dark material which formed a smooth layer.