Publications

Spectra obtained from recent telescopic observation of 1-Ceres and laboratory measurements and theoretical calculations of three component mixtures of Ceres analog material suggest that an ammoniated phyllosilicate is present on the surface of the asteroid, rather than H2O frost as had been previously reported. The presence of an ammoniated phyllosilicate, most likely ammoniated saponite...

The reflectance spectrum of Callisto from 0.2 to 4.1 μm is modeled using a simultaneous intimate plus areal mixture solution of ice and dark material which satisfies absorption band depths and reflectance levels. The model uses the radiative transfer theory based on Hapke's (1981, J. Geophys. Res. 86, 3039–3054) work, optical constants of materials and includes effects of grain size and...

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Near‐infrared and midinfrared spectra of a wide range of scapolite compositions were studied to determine the cause of the 2.36‐μm features that have been correlated with similar features in the near‐IR spectrum of Mars. We attribute the 2.36−μm features to vibrations caused by HCO3− and HSO4− in the anion sites of scapolite. The 2.36‐μm absorption complex consists of four overlapping...

patially resolved reflectance spectra of Mars in the 2.2- to 2.4-μm spectral region were obtained in August 1988 using the NASA 3-m Infrared Telescope Facility. The spectra show weak absorption features due to Martian atmospheric carbon monoxide and a surface mineral. Both CO and the mineral absorptions are composed of overlapping narrow features, but in many locations, such as Hellas...