REFLECTANCE SPECTRA OF FEATURELESS MATERIALS AND THE SURFACE MINERALOGIES OF M-CLASS AND E-CLASS ASTEROIDS

The 0.3- to 2.6-μm reflectance spectra of meteoritic enstatite (nearly pure MgSiO3), iron meteorite metal, magnetite and amorphous carbon, and various mixtures of these materials with mafix silicates have been measured in order to search for diagnostic spectral parameters which can be used to differentiate among the different materials and to provide information on the detection limits for mafic silicates. The observational data for a representative M-class asteroid, (16) Psyche, are largely consistent with a fine-grained metal-rich surface assemblage, although an enstatite chondrite-like assemblage cannot be ruled out. The observational data for the E-class asteroid (44) Nysa indicate that its surface is composed of fine-grained material similar to enstatite achondrites (aubrites), with a small amount of material comparable to the chondritic inclusions found in the Cumberland Falls aubrite. -from Authors