Optical Spectra of Lunar Dust Simulants

A comparative study of the reflectance spectra of lunar dust simulants is presented. All of the simulants except one had a wavelength-dependent reflectivity (ρ(lambda)) near 0.16 over the wavelength range of 8 to 25 micrometer, so they are highly emitting at room temperature and lower. The 300 K emittance (epsilon) of all the lunar simulants except MLS-1 ranged from 0.82 to 0.86. There was considerably more variation in the lunar simulant reflectance in the solar spectral range (250 to 2,500 nm) than in the thermal infrared. As expected, the lunar highlands simulants were more reflective in this wavelength range than the lunar mare simulants. The integrated solar absorptance (alpha) of the simulants ranged from 0.42 to 0.81. Although large spectral differences between simulant dusts and actual reported lunar dusts were observed, the integrated alpha of JSC-1AF and MLS-1P is similar to that of mare dusts, and FJS-1 and the JSC-1 have integrated alpha that match the highland dust quite well.