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The study of the radiative properties of an idealized fibrous materials reveals that the location and orientation of the fibers influence the scattering characteristics of the fabric system. The conventional model developed for the study discards the process of interference of the scattered waves from the various fibers in the fabric. The newly developed model incorporates the effects of interference to provide an accurate study.

We present a new spectrum of the Centaur object 5145 Pholus between 1.15 and 2.4 [[micro]meter]. We model this, and the previously published (0.4- to 1.0-[[micro]meter]) spectrum, using Hapke scattering theory. Seen in absorption are the 2.04-[[micro]meter] band of [H.sub.2]O ice and a strong band at 2.27 [[micro]meter], interpreted as frozen methanol and/or a photolytic product of methanol having small molecular weight. The presence of small molecules is indicative of a chemically primitive surface, since heating and other processes remove the light hydrocarbons in favor of macromolecular carbon of the kind found in carbonaceous meteorites. The unusually red slope of Pholus' spectrum is matched by fine grains of a refractory organic solid (tholin), as found previously by M. Hoffmann et al. (1993, J. Geophys. Res. 98, 7403-7407) and P. D. Wilson et al. (1994, Icarus 107, 288-303). Olivine (which we model with Fo 82) also appears to be present on Pholus. We present a five-component model for the composite spectrum of all spectroscopic and photometric data available for 5145 Pholus and conclude that this is a primitive object which has not yet been substantially processed by solar heat. The properties of Pholus are those of the nucleus of a large comet that has never been active. Key Words: asteroids, composition; comets, composition; ices, centaurs; prebiotic chemistry.

We present a new spectrum of the Centaur object 5145 Pholus between 1.15 and 2.4 [[micro]meter]. We model this, and the previously published (0.4- to 1.0-[[micro]meter]) spectrum, using Hapke scattering theory. Seen in absorption are the 2.04-[[micro]meter] band of [H.sub.2]O ice and a strong band at 2.27 [[micro]meter], interpreted as frozen methanol and/or a photolytic product of methanol having small molecular weight. The presence of small molecules is indicative of a chemically primitive surface, since heating and other processes remove the light hydrocarbons in favor of macromolecular carbon of the kind found in carbonaceous meteorites. The unusually red slope of Pholus' spectrum is matched by fine grains of a refractory organic solid (tholin), as found previously by M. Hoffmann et al. (1993, J. Geophys. Res. 98, 7403-7407) and P. D. Wilson et al. (1994, Icarus 107, 288-303). Olivine (which we model with Fo 82) also appears to be present on Pholus. We present a five-component model for the composite spectrum of all spectroscopic and photometric data available for 5145 Pholus and conclude that this is a primitive object which has not yet been substantially processed by solar heat. The properties of Pholus are those of the nucleus of a large comet that has never been active. Key Words: asteroids, composition; comets, composition; ices, centaurs; prebiotic chemistry.