EXAMINING EJECTA PROPERTIES FOR YOUNG LUNAR CRATERS USING MINI-RF BISTATIC OBSERVATIONS

The Mini-RF radar onboard the Lunar Reconnaissance Orbiter (LRO) is currently operating in a bistatic configuration using the Goldstone DSS-13 and Arecibo Observatory as transmitters in X-band (4.2-cm) and S-band (12.6 cm), respectively. A typical product examining the scattering properties of the lunar surface that can be derived from backscattered microwave radiation is the Circular Polarization Ratio (CPR). The CPR of a surface can be interpreted as an indication of the roughness of the surface on the wavelength of the radar. Here, we examine the ejecta blankets of Copernican aged craters on the lunar surface in both S- and X-band to examine the scattering properties of young crater ejecta. Several observed craters and their ejecta blankets exhibit a clear opposition effect at low bistatic (phase) angles. This opposition effect is consistent with optical studies of lunar soils done in the laboratory, but these observations are the first time this effect has been measured on the Moon at radar wavelengths. The style of the opposition effect differs between craters, which may indicate differences in ejecta fragment formation or emplacement. Differences in the CPR behavior as a function of bistatic angle may also provide opportunities for relative age dating between Copernican craters. Here, we examine the ejecta of nine Copernican and Eratosthenian aged craters in both S-band and X-band and document CPR characteristics as a function bistatic angle in order to test that hypothesis. Observing the scattering behavior of continuous ejecta blankets in multiple wavelengths may provide further information about the rate of breakdown of rocks of varying size to provide increased understanding of how impacts produce regolith on the Moon.