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 similar studies on smaller craters are lacking mainly due to data resolution limitations. Here we present a detailed quantification on spatial deposition of ejecta for small-sized lunar craters (<6 km). Using data from Mini RF instrument on-board NASA's Lunar Reconnaissance Orbiter, four Stokes parameters that differentiate and describe the observed backscattered electromagnetic field are calculated. We use the first Stokes parameter to investigate and estimate the spatial ejecta distribution for 98 small-sized fresh and degraded 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 degradation rate appears higher for highland region compared to mare region.

Retrieving volume FeO and TiO2 abundances of lunar regolith with CE-2 CELMS data using BPNN method*

“…The difference between the Clementine results and CELMS results is probably from contamination of the impact ejecta from other regions, which plays an important role in the measured optical data (Lucey et al 1998;Wu et al 2012). After all, Aristarchus, Copernicus and Kepler craters are located not far from the belt, and even the ejecta from Tycho crater at a far distance also altered the surface compositions to some extent (Desai et al 2014). Moreover, Adams et al (1978);Haruyama et al (2009) suggested that higher FTAs mostly appear in younger basalts.…”