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VIS‐NIR reflectance of water ice/regolith analogue mixtures and implications for the detectability of ice mixed within planetary regoliths
Author(s) -
Yoldi Zuriñe,
Pommerol Antoine,
Jost Bernhard,
Poch Olivier,
Gouman Julien,
Thomas Nicolas
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl064780
Subject(s) - regolith , water ice , reflectivity , remote sensing , geology , mercury (programming language) , near infrared spectroscopy , ice crystals , astrobiology , mineralogy , environmental science , materials science , optics , physics , computer science , programming language
Permanently shadowed regions at the poles of the Moon and Mercury have been pointed out as candidates for hosting water ice at their surface. We have measured in the laboratory the visible and near infrared spectral range (VIS‐NIR) bidirectional reflectance of intimate mixtures of water ice and the JSC‐1AF lunar simulant for different ice concentrations, particle sizes, and measurement geometries. The nonlinearity between the measured reflectance and the amount of ice in the mixture can be reproduced to some extent by the mixing formulas of standard reflectance models, in particular, those of Hapke and Hiroi, which are tested here. Estimating ice concentrations from reflectance data without knowledge of the mixing coefficients—strongly dependent on the size/shape of the grains—can result in large errors. According to our results, it is possible that considerable amounts of water ice might be intimately mixed in the regolith of the Moon and Mercury without producing noticeable photometric signatures.