Temporal variations of Titan’s surface with Cassini/VIMS

Solomonidou, Anezina; Coustenis, A.; Hirtzig, M.; Rodríguez, S.; Stephan, K.; Lopes-Gautier, R.; Drossart, P.; Sotin, C.; Mouëlic, Stéphane Le; Lawrence, K.; Bratsolis, E.; Jaumann, R.; Brown, R. H.

doi:10.1016/j.icarus.2015.05.003

Cited by 31 publications

(55 citation statements)

References 87 publications

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“…Titan's atmosphere is divided into 70 layers, and the calculations for each layer are based on the vertical profiles of pressure and temperature measured by the Huygens probe's Atmospheric Structure Instrument (Fulchignoni et al, ), the methane vertical mixing ratio from the Huygens Gas Chromatograph Mass Spectrometer (Niemann et al, ), and on a uniform CO mole fraction equal to 4.5 × 10 −5 based on Cassini Composite Infrared Spectrometer measurements (de Kok et al, ). Updates of the code and improvements on our method for albedo retrievals in the RoIs were implemented and described in detail in Solomonidou et al (, ), Bonnefoy et al (), and Lopes et al ().…”

Section: Process and Methods Of Analysismentioning

confidence: 99%

“…In our analysis, the atmospheric scattering and absorption are evaluated prior to extracting the contribution from the surface. Hirtzig et al () and Solomonidou et al (, ) describe the details of the method and the model applied here, but a brief description is also provided in section 2. As in our previous studies, the selection of regions of interest (RoIs) included in this study is based on the scientific significance that a region or feature offers and the availability of VIMS data compatible with our RT plane‐parallel geometry.…”

Section: Context and Observationsmentioning

confidence: 99%

“…In addition, we provided implications for the undifferentiated plains' ( pul1 and pul2 ) possible composition in Lopes et al (), where we proposed tholin‐like material to be the major constituent. Furthermore, the temporal variations of the undifferentiated plains and the dunes were studied in Solomonidou et al (), who found that the dunes (from 2005 to 2012) and the undifferentiated plains (from 2010 to 2012) did not present any change in albedo with time.…”

Section: Context and Observationsmentioning

confidence: 99%

“…In Figure we show Caladan Planitia 1 and 2 (two distinct regions of undifferentiated plains) in a single rectangular box called “Caladan Planitia” in addition to three more regions of undifferentiated plains. We also analyze the same HLS datacube selection from the Tb flyby as used for calibration and reference area in Solomonidou et al (, ) and Lopes et al ().…”

Section: Context and Observationsmentioning

confidence: 99%

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

et al. 2018

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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.

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Section: Process and Methods Of Analysismentioning

confidence: 99%

Section: Context and Observationsmentioning

confidence: 99%

Section: Context and Observationsmentioning

confidence: 99%

Section: Context and Observationsmentioning

confidence: 99%

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

et al. 2018

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“…Different correction methods have been developed and applied to compensate for these effects. In this study, we will use two methods: a fast semiempirical correction for IR units identification and mapping purposes (Combes et al, 1997;Cornet et al, 2012;Coustenis et al, 2001Coustenis et al, , 2005Le Mouélic et al, 2012) and a comprehensive radiative transfer model in order to retrieve more precisely the albedo of the surface units and their composition (Hirtzig et al, 2013;Maltagliati et al, 2015;Solomonidou et al, 2014Solomonidou et al, , 2016Solomonidou et al, , 2018.…”

Section: Infrared Unit Mapping With Vims and Imaging Science Subsystemmentioning

confidence: 99%

Geological Evolution of Titan's Equatorial Regions: Possible Nature and Origin of the Dune Material

et al. 2018

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In 13 years, infrared observations from the Visual and Infrared Mapping Spectrometer onboard Cassini provided significant hints about the spectral and geological diversity of Titan's surface. The analysis of the infrared (IR) signature of spectral units enables constraining the surface composition, which is crucial for understanding possible interactions between Titan's interior, surface, and atmosphere. Here we investigate a selection of areas in the equatorial regions, imaged by Cassini's instruments, which exhibit an apparent transition from the Visual and Infrared Mapping Spectrometer IR‐bright to the IR‐blue and IR‐brown units (from false‐color composites using red: 1.57/1.27 μm, green: 2.01/1.27 μm, and blue: 1.27/1.08 μm). By applying an updated radiative transfer model, we extract the surface albedo of IR units identified in these regions. Then, we compare them with synthetic mixtures of two expected components on Titan's surface, namely, water ice and laboratory tholins. This allows us to reconnect the derived composition and grain size information to the geomorphology observed from Radio Detection and Ranging instrument (RADAR)/Synthetic Aperture Radar images. We interpret IR‐bright units as hills and plains coated by organic material and incised by fluvial networks. Erosion products are transported downstream to areas where IR‐blue units are seen near the IR‐bright units. These units, enriched in water ice, are most likely outwash plains hosting debris from fluvial erosion. Farther away from the IR‐bright units, the IR‐brown units are dominantly made of organics with varied grain sizes, ranging from dust‐ to sand‐sized particles that form the dune fields. The transition areas therefore exhibit trends in water ice content and grain size supported by geomorphological observations.

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Titan

Coustenis¹,

Raulin²

2019

Encyclopedia of Astrobiology

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Temporal variations of Titan’s surface with Cassini/VIMS

Cited by 31 publications

References 87 publications

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

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

Geological Evolution of Titan's Equatorial Regions: Possible Nature and Origin of the Dune Material

Titan

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