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The Spectral Nature of Titan's Major Geomorphological Units: Constraints on Surface Composition

Solomonidou, A. and Elachi, C. (2018) The Spectral Nature of Titan's Major Geomorphological Units: Constraints on Surface Composition. Journal of Geophysical Research. Planets, 123 (2). pp. 489-507. ISSN 2169-9097. doi:10.1002/2017JE005477.

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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.

Item Type:Article
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Solomonidou, A.0000-0002-4033-5898
Additional Information:© 2018 American Geophysical Union. Received 2 NOV 2017; Accepted 25 JAN 2018; Accepted article online 29 JAN 2018; Published online 22 FEB 2018. All Cassini data used in this article can be accessed in the Planetary Data Systems (PDS). The spectral library databases can be accessed here: This research was supported by the Cassini Data Analysis and Participating Scientists Program (CDAPS) grant NH16ZDA001N to R.L. We also acknowledge the support from the French National Research Agency for the ANR project “CH4@Titan” (ref: BLAN08‐2_321467). S. R. also acknowledges financial support from the UnivEarthS LabEx program of Sorbonne Paris Cite (ANR‐10‐LABX‐0023 and ANR‐11‐IDEX‐0005‐02) and the French National Research Agency (ANR‐APOSTIC‐11‐BS56‐002 and ANR‐12‐BS05‐001‐3/EXO‐DUNES). This work was conducted at Jet Propulsion Laboratory (JPL) and the California Institute of Technology (Caltech) under contract with NASA. The authors would like to thank Thomas McCord and another anonymous reviewer for their very useful comments. ©2017 California Institute of Technology. Government sponsorship acknowledged.
Group:Astronomy Department
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)BLAN08-2_321467
Agence Nationale pour la Recherche (ANR)ANR-10-LABX-0023
Agence Nationale pour la Recherche (ANR)ANR-11-IDEX-0005-02
Agence Nationale pour la Recherche (ANR)ANR-APOSTIC-11-BS56-002
Agence Nationale pour la Recherche (ANR)ANR-12-BS05-001-3/EXO-DUNES
Subject Keywords:Titan geology; geomorphological units; spectral behavior; radiative transfer; Titan composition; saturnian satellites
Issue or Number:2
Record Number:CaltechAUTHORS:20180131-111642172
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Official Citation:Solomonidou, A., Coustenis, A., Lopes, R. M. C., Malaska, M. J., Rodriguez, S., Drossart, P., et al. (2018). The spectral nature of Titans major geomorphological units: Constraints on surface composition. Journal of Geophysical Research: Planets, 123, 489–507.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84601
Deposited By: Tony Diaz
Deposited On:31 Jan 2018 19:24
Last Modified:15 Nov 2021 20:21

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