Impact Ejecta Characterization for Small-Sized Fresh and Degraded Lunar Craters Using Radar Data

Abstract

Ejecta distribution studies for large-sized (>10 km) lunar craters have been carried out earlier, but simi-lar studies on smaller craters are lacking mainly due to data resolution limitations. Here we present a de-tailed quantification on spatial deposition of ejecta for small-sized lunar craters (<6 km). Using data from Mini RF instrument on-board NASA's Lunar Recon-naissance Orbiter, four Stokes parameters that differ-entiate and describe the observed backscattered electromagnetic field are calculated. We use the first Stokes parameter to investigate and estimate the spa-tial ejecta distribution for 98 small-sized fresh and de-graded craters from mare and highland regions. It is observed that ejecta distribution can be described using power law with crater diameter and depth/ diameter (d/D) ratio. Ejecta behaviour is analysed for both the terrain types, highland and mare, enabling us to understand the effect and dependency of target rock properties on the ejecta characteristics. Further, the d/D dependence has indicated that the relative de-gradation rate appears higher for highland region compared to mare region.