Relative spectral reflectivity 0.4-1μ of selected areas of the lunar surface

The relative spectral reflectivity, 0.72 to 1.10μ, was measured for several areas of the lunar surface. A double-beam photoelectric filter photometer was used with the 24- and 60-inch (0.61 and 1.52 meter) telescopes on Mount Wilson. The infrared relative spectral curves were combined with curves for the visible portion of the spectrum obtained in an earlier study. The combined curves have considerable structure, which differs with lunar area and is correlated with lunar morphology. The series of curves cannot be derived from a linear combination of any two end-member curves. The spectral structure does not seem to correlate with relative age of the lunar areas. The position and structure of spectral features present in the curves are similar to absorption bands found in the reflectance spectrum for common terrestrial silicate materials. These results suggest that compositional and mineralogical differences on the lunar surface are responsibile for the relative spectral reflectivity differences. If this interpretation is accepted, then the lunar surface, and especially the maria, are not mineralogically uniform. Correlation between lunar and laboratory spectral reflectivity curves suggests that remote mineralogical analysis of planetary surfaces may be possible by use of reflection spectroscopy in the visible and near infrared wavelength region.