CORRECTING IMPACT MIXING REVEALS UNDERLYING GRAIN DENSITY IN THE LUNAR CRUST

Grain density is an important input parameter to the derivation of porosity in gravity analysis. The high resolution data derived from Gravity and Recovery Interior Laboratory (GRAIL) have been used to derive the crustal porosity by comparing bulk density estimates to the estimates of observed grain density in the lunar crust. Iron and titanium oxide abundances retrieved from Lunar Prospector Gamma-Ray Spectrometer (LP-GRS) and measured from in-situ returned samples are utilized to derive this observed grain density. Although the derived grain density using LP-GRS data for the lunar crust is closer to the true grain density of the underlying crust than the estimate from the visible spectral reflectance data, the ≤1 meter deep column of the lunar regolith is well-mixed products of variety of materials. The main goal of the study attempts to recover a true grain density of a underlying crust in the most pristine highlands, the lunar northern central farside.