TY - JOUR
T1 - The Spectral Nature of Titan's Major Geomorphological Units
T2 - Constraints on Surface Composition
AU - Solomonidou, A.
AU - Coustenis, A.
AU - Lopes, R. M.C.
AU - Malaska, M. J.
AU - Rodriguez, S.
AU - Drossart, P.
AU - Elachi, C.
AU - Schmitt, B.
AU - Philippe, S.
AU - Janssen, M.
AU - Hirtzig, M.
AU - Wall, S.
AU - Sotin, C.
AU - Lawrence, K.
AU - Altobelli, N.
AU - Bratsolis, E.
AU - Radebaugh, J.
AU - Stephan, K.
AU - Brown, R. H.
AU - Le Mouélic, S.
AU - Le Gall, A.
AU - Villanueva, E. V.
AU - Brossier, J. F.
AU - Bloom, A. A.
AU - Witasse, O.
AU - Matsoukas, C.
AU - Schoenfeld, A.
N1 - Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2018/2
Y1 - 2018/2
N2 - We investigate Titan's low-latitude and midlatitude surface using spectro-imaging near-infrared data from Cassini/Visual and Infrared Mapping Spectrometer. We use a radiative transfer code to first evaluate atmospheric contributions and then extract the haze and the surface albedo values of major geomorphological units identified in Cassini Synthetic Aperture Radar data, which exhibit quite similar spectral response to the Visual and Infrared Mapping Spectrometer data. We have identified three main categories of albedo values and spectral shapes, indicating significant differences in the composition among the various areas. We compare with linear mixtures of three components (water ice, tholin-like, and a dark material) at different grain sizes. Due to the limited spectral information available, we use a simplified model, with which we find that each albedo category of regions of interest can be approximately fitted with simulations composed essentially by one of the three surface candidates. Our fits of the data are overall successful, except in some cases at 0.94, 2.03, and 2.79 μm, indicative of the limitations of our simplistic compositional model and the need for additional components to reproduce Titan's complex surface. Our results show a latitudinal dependence of Titan's surface composition, with water ice being the major constituent at latitudes beyond 30°N and 30°S, while Titan's equatorial region appears to be dominated partly by a tholin-like or by a very dark unknown material. The albedo differences and similarities among the various geomorphological units give insights on the geological processes affecting Titan's surface and, by implication, its interior. We discuss our results in terms of origin and evolution theories.
AB - We investigate Titan's low-latitude and midlatitude surface using spectro-imaging near-infrared data from Cassini/Visual and Infrared Mapping Spectrometer. We use a radiative transfer code to first evaluate atmospheric contributions and then extract the haze and the surface albedo values of major geomorphological units identified in Cassini Synthetic Aperture Radar data, which exhibit quite similar spectral response to the Visual and Infrared Mapping Spectrometer data. We have identified three main categories of albedo values and spectral shapes, indicating significant differences in the composition among the various areas. We compare with linear mixtures of three components (water ice, tholin-like, and a dark material) at different grain sizes. Due to the limited spectral information available, we use a simplified model, with which we find that each albedo category of regions of interest can be approximately fitted with simulations composed essentially by one of the three surface candidates. Our fits of the data are overall successful, except in some cases at 0.94, 2.03, and 2.79 μm, indicative of the limitations of our simplistic compositional model and the need for additional components to reproduce Titan's complex surface. Our results show a latitudinal dependence of Titan's surface composition, with water ice being the major constituent at latitudes beyond 30°N and 30°S, while Titan's equatorial region appears to be dominated partly by a tholin-like or by a very dark unknown material. The albedo differences and similarities among the various geomorphological units give insights on the geological processes affecting Titan's surface and, by implication, its interior. We discuss our results in terms of origin and evolution theories.
KW - Titan composition
KW - Titan geology
KW - geomorphological units
KW - radiative transfer
KW - saturnian satellites
KW - spectral behavior
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U2 - 10.1002/2017JE005477
DO - 10.1002/2017JE005477
M3 - Article
AN - SCOPUS:85042305497
VL - 123
SP - 489
EP - 507
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 2169-897X
IS - 2
ER -