Modelling of lunar crater ejecta extent for highland and mare using Mini-RF data

摘要

Previously using radar it was for the first time established that it is possible to quantify lunar ejecta in terms of spatial extent and can be characterized into fine and coarse based on radar backscatter effects. We also described that ejecta extent consistently increases with increase in crater diameter and is best related using power law equations. Here we describe utility of SAR to measure spatial ejecta extent for small sized (0.2 to 6 km) fresh and degraded craters and further extend our investigations to understand the variability in spatial ejecta extent derived in response to the change in target rock strength. We also analyze relation between ejecta distribution and crater diameter. Comprehensive analysis of 98 fresh and degraded craters from mare and highland regions composed of two entirely distinct rocks namely basalt and anorthosites respectively was carried out. Our observations show that spatial ejecta extent consistently increases with increase in crater diameter and is best related by power law equations. We also observe the amount of ejecta expelled and its subsequent surface deposition to be highly dependent on the physical attributes of the target rock. Extent tends to be greater for highland than compared to mare owing to the difference in rock strength. Based on this fact, highland fresh craters are thus observed to have highest amount of expelled and preserved ejecta.