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Spectral and emissivity analysis of the raised ramparts around Titan's northern lakes

Solomonidou, A. and Le Gall, A. and Malaska, M. J. and Birch, S. P. D. and Lopes, R. M. C. and Coustenis, A. and Rodriguez, S. and Wall, S. D. and Michaelides, R. J. and Nasr, M. R. and Elachi, C. and Hayes, A. G. and Soderblom, J. M. and Schoenfeld, A. M. and Matsoukas, C. and Drossart, P. and Janssen, M. A. and Lawrence, K. J. and Witasse, O. and Yates, J. and Radebaugh, J. (2020) Spectral and emissivity analysis of the raised ramparts around Titan's northern lakes. Icarus, 344 . Art. No. 113338. ISSN 0019-1035. doi:10.1016/j.icarus.2019.05.040.

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Some of Titan's small northern hemisphere lakes show raised rampart features (which are distinct from raised rims), and appear as SAR-bright mound-like annuli extending away from the lake for up to tens of kilometers from the shoreline. We investigate the infrared and microwave characteristics of these features using Cassini Visual and Infrared Mapping Spectrometer (VIMS) and RADAR data. A spectral comparative analysis is performed among the lakes, their ramparts, and the surrounding regions. We overcome the profound difference in spatial resolution between VIMS and SAR data by using a method that provides overlays between the spectral images and SAR, thus enabling the correct selection of VIMS pixels. The surface properties of the selected areas are obtained using a radiative transfer analysis on the selected VIMS pixels, in addition to emissivity obtained from the RADAR in radiometry mode. Analysis of these combined and co-registered data provides constraints for the formation mechanism(s) of raised ramparts. The results show that the emissivity of the raised ramparts is close to that of Titan's labyrinthic terrains and to that of empty lake floors in the northern polar regions. This is confirmed by the VIMS analysis that also shows that the infrared spectral response of the raised ramparts is very similar to that of some empty lake floors. This suggests that both areas are made from or are covered by a similar material. In addition, two out of the eight lakes with raised ramparts show spectral differences at three specific wavelengths, 1.6, 2.0, and 5.0 μm, between the ramparts and the surrounding terrain. We hypothesize that this could be due to some component, or mixture of components in the ramparts that is less absorbent at these specific wavelengths, or it could be an effect of different grain sizes. These observations provide first insights into the possible mechanisms leading to the formation of the raised ramparts that are discussed here.

Item Type:Article
Related URLs:
URLURL TypeDescription
Solomonidou, A.0000-0002-4033-5898
Birch, S. P. D.0000-0002-4578-1694
Soderblom, J. M.0000-0003-3715-6407
Janssen, M. A.0000-0001-5476-731X
Additional Information:© 2019 Elsevier. Received 18 December 2018, Revised 9 April 2019, Accepted 29 May 2019, Available online 15 June 2019. All Cassini data used in this article can be accessed in the Planetary Data Systems (PDS). This research was partly supported by the NASA Astrobiology Institute through its JPL-led project entitled Habitability of Hydrocarbon Worlds: Titan and Beyond. This research was partly supported by the Cassini Data Analysis and Participating Scientists Program (CDAPS) grant #NH16ZDA001N to RL. AS is supported by a European Space Agency (ESA) Research Fellowship at the European Space Astronomy Centre (ESAC), in Madrid, Spain. ALG and SR are supported by IUF (Institut Universitaire de France). This work was partly conducted at Jet Propulsion Laboratory (JPL) and the California Institute of Technology (Caltech) under contract with NASA. © 2018 California Institute of Technology. Government sponsorship acknowledged.
Group:Astronomy Department
Funding AgencyGrant Number
European Space Agency (ESA)UNSPECIFIED
Institut Universitaire de France (IUF)UNSPECIFIED
Subject Keywords:Titan surface; Titan hydrology; Radar observations; Spectroscopy; Radiative transfer
Record Number:CaltechAUTHORS:20190617-104717738
Persistent URL:
Official Citation:A. Solomonidou, A. Le Gall, M.J. Malaska, S.P.D. Birch, R.M.C. Lopes, A. Coustenis, S. Rodriguez, S.D. Wall, R.J. Michaelides, M.R. Nasr, C. Elachi, A.G. Hayes, J.M. Soderblom, A.M. Schoenfeld, C. Matsoukas, P. Drossart, M.A. Janssen, K.J. Lawrence, O. Witasse, J. Yates, J. Radebaugh, Spectral and emissivity analysis of the raised ramparts around Titan's northern lakes, Icarus, Volume 344, 2020, 113338, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96462
Deposited By: George Porter
Deposited On:17 Jun 2019 19:45
Last Modified:16 Nov 2021 17:21

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