Phase-ratio imagery as a planetary remote-sensing tool

We present a new optical remote-sensing technique called phase-ratio imagery that suggests an estimation of sub-resolution roughness of the surface of atmosphereless celestial bodies including the Moon. Lunar images acquired by the Narrow Angle Camera on the Lunar Reconnaissance Orbiter are used as illustrations. The technique is used for 3D phase-ratio imagery of several areas in the lunar craters Kepler and Cauchy. This allows observations of complicated impact melt movements on the flanks and the floors of the craters. However, in many cases, flow structures seen on the inner wall can be attributed to regolith/debris taluses, and not impact melt flows. ► We present phase-ratio images of lunar craters Kepler and Cauchy. ► Images show complicated impact melt movements on the flanks of the craters. ► Other flow structures appear to be taluses. ► Phase-ratio images provide additional information to albedo images.