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Io: Precise Comparison of Voyager Spectral Curves with Laboratory MeasurementsIn order to derive more accurate normal reflectances of regions on Io, the near-opposition (alpha 10 deg) photometry of a set of regions on the 20 W face of the satellite, the face with the most complete near-opposition Voyager imaging coverage was analyzed. Sixty-eight regions were chosen for study, each approximately 120 km on a side, and divided into three coherent color classes: white, orange, and polar brown regions. Derived Minneart parameters, while generally consistent with previous limb darkening determinations, show that: (1) for the white regions, k rises linearly with increasing B(0), which is the trend to be expected for normal materials; (2) the white regions are slightly limb brightened (k 0.5) at low wavelengths (low values of B(0)); and (3) k appears to drop with rising B(0) for the orange regions, contrary to the trend expected for most materials. Despite similar reflectances, there is one group of orange regions with large opposition surges and a second group showing significantly lower surges, possibly indicating differences in surface texture (porosity and/or particle size).
Document ID
Acquisition Source
Legacy CDMS
Document Type
Simonelli, D. P.
(Cornell Univ. Ithaca, NY, United States)
Veverka, J.
(Cornell Univ. Ithaca, NY, United States)
Date Acquired
August 12, 2013
Publication Date
April 1, 1985
Publication Information
Publication: NASA, Washington Repts. of Planetary Geol. and Geophys. Program, 1984
Subject Category
Lunar And Planetary Exploration
Accession Number
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
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