SPECTRAL-CHEMICAL ANALYSIS OF LUNAR-SURFACE MATERIALS

Samples of lunar rocks and soils that have been examined in the laboratory both spectroscopically and chemically were analyzed with the goal of identifying and quantifying correlations between reflectance spectra and compositional properties of lunar materials. The method used to quantify spectral variations within the set of spectral samples is principal component analysis. The correlations between the chemical analysis of lunar samples and their spectral quantities are determined by using multivariate analysis. The combination of both methods yields functional relationships between the principal axes of variation and the chemical constituents, in particular, FeO, TiO2, SiO2, Al2O3, MgO, CaO, and MnO, and with the content of amorphous materials (glass) in lunar samples. To first order, the nature of these relationships is found to be linear. The results define a spectral-chemical model that is applicable to derive abundances of chemical constituents and amorphous components from individual spectra. The accuracy of the model is better than +/- 2.4 wt % and +/- 4% for chemical constituents and amorphous components. respectively, making the model also sensitive to remotely sensed spectra of the lunar surface.