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1. Detailed chemical composition analysis of the Soi crater region on Titan

Author

Solomonidou, A., Malaska, M. J., Lopes, R. M.C., Coustenis, A., Schoenfeld, A. M., Schmitt, B., Birch, S. P.D., Le Gall, A., Lawrence, K., Matsoukas, Christos, Wall, S. D., Elachi, C., Solomonidou, A., Malaska, M. J., Lopes, R. M.C., Coustenis, A., Schoenfeld, A. M., Schmitt, B., Birch, S. P.D., Le Gall, A., Lawrence, K., Matsoukas, Christos, Wall, S. D., and Elachi, C.

Abstract

The Soi crater region (0° to 60°N, 180°W to −110°W), which includes the well-preserved Soi crater in its center, spans a region from Titan's aeolian-dominated equatorial regions to fluvially-dominated high northern latitudes. This provides a rich diversity of landscapes, one that is also representative of the diversity encountered across Titan. Schoenfeld et al. (2023) mapped this region at 1:800,000 scale and produced a geomorphological map showing that the area consists of 22 types of geomorphological units. The Visual and Infrared Mapping Spectrometer (VIMS) coverage of the region enabled the detailed analysis of spectra of 261 different locations using a radiative transfer technique and a mixing model, yielding compositional constraints on Titan's optical surface layer. Additional constraints on composition on the near-surface substrate were obtained from microwave emissivity. We have derived combinations of top surface materials between dark materials, tholins, water-ice, and methane suggesting that dark mobile organic material at equatorial and high latitudes indicates “young” terrains and compositions, while tholin/water-ice mixtures that dominate areas around latitude 35°N show a material that is older plains deposits that we interpret to be the end stage of aeolian and fluvial transport and deposition. We found no spectral evidence of CO2, HC3N, and NH3 ice. We use the stratigraphic relations between the various mapping units and the relation between the geomorphology and the composition of the surface layers to build hypotheses on the origin and evolution of the regional geology. We suggest that sedimentary deposits, likely aeolian, are dominant in the region with fluvial activity and leaching changing the nature of the top surfaces of the midlatitude areas of the Soi crater region., QC 20240827

Published
2024
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6. The next frontier for planetary and human exploration

Author

Stamenković, V., Beegle, L. W., Zacny, K., Arumugam, D. D., Baglioni, P., Barba, N., Baross, J., Bell, M. S., Bhartia, R., Blank, J. G., Boston, P. J., Breuer, D., Brinckerhoff, W., Burgin, M. S., Cooper, I., Cormarkovic, V., Davila, A., Davis, R. M., Edwards, C., Etiope, G., Fischer, W. W., Glavin, D. P., Grimm, R. E., Inagaki, F., Kirschvink, J. L., Kobayashi, A., Komarek, T., Malaska, M., Michalski, J., Ménez, B., Mischna, M., Moser, D., Mustard, J., Onstott, T. C., Orphan, V. J., Osburn, M. R., Plaut, J., Plesa, A.-C., Putzig, N., Rogers, K. L., Rothschild, L., Russell, M., Sapers, H., Lollar, B. Sherwood, Spohn, T., Tarnas, J. D., Tuite, M., Viola, D., Ward, L. M., Wilcox, B., and Woolley, R.

Published
2019
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7. Titan as Revealed by the Cassini Radar

Author

Lopes, R. M. C., Wall, S. D., Elachi, C., Birch, S. P. D., Corlies, P., Coustenis, A., Hayes, A. G., Hofgartner, J. D., Janssen, M. A., Kirk, R. L., LeGall, A., Lorenz, R. D., Lunine, J. I., Malaska, M. J., Mastroguiseppe, M., Mitri, G., Neish, C. D., Notarnicola, C., Paganelli, F., Paillou, P., Poggiali, V., Radebaugh, J., Rodriguez, S., Schoenfeld, A., Soderblom, J. M., Solomonidou, A., Stofan, E. R., Stiles, B. W., Tosi, F., Turtle, E. P., West, R. D., Wood, C. A., Zebker, H. A., Barnes, J. W., Casarano, D., Encrenaz, P., Farr, T., Grima, C., Hemingway, D., Karatekin, O., Lucas, A., Mitchell, K. L., Ori, G., Orosei, R., Ries, P., Riccio, D., Soderblom, L. A., and Zhang, Z.

Published
2019
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8. Geomorphological Map of the Soi Crater Region on Titan

Author

Schoenfeld, A. M., primary, Solomonidou, A., additional, Malaska, M. J., additional, Lopes, R. M. C., additional, Birch, S. P. D., additional, Le Mouélic, S., additional, Florence, M., additional, Verlander, T., additional, Wall, S. D., additional, and Elachi, C., additional

Published
2023
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11. Delving Into Ocean World Interiors

Author

Malaska, M, Shaw, G, Abramson, E. H, Journaux, B, Bollengier, O, Brown, J. M, and Vance, Steve

Abstract

UNKNOWN

Published
2018

17. Titan as Revealed by the Cassini Radar

Author

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Lopes, R. M C, Wall, S. D, Elachi, C., Birch, S. P D, Corlies, P., Coustenis, A., Hayes, A. G, Hofgartner, J. D, Janssen, M. A, Kirk, R. L, LeGall, A., Lorenz, R. D, Lunine, J. I, Malaska, M. J, Mastroguiseppe, M., Mitri, G., Neish, C. D, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Lopes, R. M C, Wall, S. D, Elachi, C., Birch, S. P D, Corlies, P., Coustenis, A., Hayes, A. G, Hofgartner, J. D, Janssen, M. A, Kirk, R. L, LeGall, A., Lorenz, R. D, Lunine, J. I, Malaska, M. J, Mastroguiseppe, M., Mitri, G., and Neish, C. D

Abstract

Titan was a mostly unknown world prior to the Cassini spacecraft’s arrival in July 2004. We review the major scientific advances made by Cassini’s Titan Radar Mapper (RADAR) during 13 years of Cassini’s exploration of Saturn and its moons. RADAR measurements revealed Titan’s surface geology, observed lakes and seas of mostly liquid methane in the polar regions, measured the depth of several lakes and seas, detected temporal changes on its surface, and provided key evidence that Titan contains an interior ocean. As a result of the Cassini mission, Titan has gone from an uncharted world to one that exhibits a variety of Earth-like geologic processes and surface-atmosphere interactions. Titan has also joined the ranks of “ocean worlds” along with Enceladus and Europa, which are prime targets for astrobiological research.

Published
2021

18. The chemical composition of impact craters on Titan

Author

Solomonidou, A., primary, Neish, C., additional, Coustenis, A., additional, Malaska, M., additional, Le Gall, A., additional, Lopes, R. M. C., additional, Werynski, A., additional, Markonis, Y., additional, Lawrence, K., additional, Altobelli, N., additional, Witasse, O., additional, Schoenfeld, A., additional, Matsoukas, C., additional, Baziotis, I., additional, and Drossart, P., additional

Published
2020
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19. The chemical composition of impact craters on Titan : I. Implications for exogenic processing

Author

Solomonidou, A., Neish, C., Coustenis, A., Malaska, M., Le Gall, A., Lopes, R. M. C., Werynski, A., Markonis, Y., Lawrence, K., Altobelli, N., Witasse, O., Schoenfeld, A., Matsoukas, Christos, Baziotis, I., Drossart, P., Solomonidou, A., Neish, C., Coustenis, A., Malaska, M., Le Gall, A., Lopes, R. M. C., Werynski, A., Markonis, Y., Lawrence, K., Altobelli, N., Witasse, O., Schoenfeld, A., Matsoukas, Christos, Baziotis, I., and Drossart, P.

Abstract

We investigate the spectral behavior of nine Titan impact craters in order to constrain their composition. Past studies that have examined the chemical composition of impact craters on Titan have either used qualitative comparisons between craters or combined all craters into a single unit, rather than separating them by geographic location and/or degradation state. Here, we use Visual and Infrared Mapping Spectrometer (VIMS) data and a radiative transfer code to estimate the atmospheric contribution to the data, extract the surface albedos of the impact craters, and constrain their composition by using a library of candidate Titan materials, including essentially water ice, tholin, a dark component, and other possible ices at different grain sizes. Following a general characterization of the impact craters, we study two impact crater subunits, the "crater floor" and the "ejecta blanket". The results show that the equatorial dune craters - Selk, Ksa, Guabonito, and the crater on Santorini Facula - appear to be purely composed of organic material (mainly an unknown dark component). Titan's midlatitude plain craters - Afekan, Soi, and Forseti - along with Menrva and Sinlap, are enriched in water ice within an organic-based mixture. This follows the geographic pattern observed in our previous work with VIMS data, where the uppermost layers of the midlatitude alluvial fans, undifferentiated plains, and labyrinth terrains were found to consist of a mixture of organics and water ice, while the equatorial plains, hummocky terrains, and dunes were found to consist of a mixture of dark material and tholins. Furthermore, we found that the addition of some form of ice improves the fit in the ejecta spectra of Afekan and Sinlap craters. We find no indication for the presence of either NH3 or CO2 ice. Our main results agree with an existing Titan surface evolution scenario, wherein the impact cratering process produces a mixture of organic material and water ice, which is later, QC 20201201

Published
2020
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20. Spectral and emissivity analysis of the raised ramparts around Titan's northern lakes

Author

Solomonidou, A., Le Gall, A., Malaska, M. J., Birch, S. P. D., Lopes, R. M. C., Coustenis, A., Rodriguez, S., Wall, S. D., Michaelides, R. J., Nasr, M. R., Elachi, C., Hayes, A. G., Soderblom, J. M., Schoenfeld, A. M., Matsoukas, Christos, Drossar, P., Janssen, M. A., Lawrence, K. J., Witasse, O., Yates, J., Radebaugh, J., Solomonidou, A., Le Gall, A., Malaska, M. J., Birch, S. P. D., Lopes, R. M. C., Coustenis, A., Rodriguez, S., Wall, S. D., Michaelides, R. J., Nasr, M. R., Elachi, C., Hayes, A. G., Soderblom, J. M., Schoenfeld, A. M., Matsoukas, Christos, Drossar, P., Janssen, M. A., Lawrence, K. J., Witasse, O., Yates, J., and Radebaugh, J.

Abstract

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 mu m, 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., QC 20200713

Published
2020
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21. A global geomorphologic map of Saturn’s moon Titan

Author

Lopes, R. M. C., primary, Malaska, M. J., additional, Schoenfeld, A. M., additional, Solomonidou, A., additional, Birch, S. P. D., additional, Florence, M., additional, Hayes, A. G., additional, Williams, D. A., additional, Radebaugh, J., additional, Verlander, T., additional, Turtle, E. P., additional, Le Gall, A., additional, and Wall, S. D., additional

Published
2019
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23. Dissolution geology of organic materials on Saturn’s moon Titan: alien analogs of terrestrial karst

Author

Malaska, M. J., Robert Hodyss, Karl Mitchell, Thomas Cornet, Cyril Fleurant, Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), Littoral, Environnement, Télédétection, Géomatique ( LETG - Angers ), Littoral, Environnement, Télédétection, Géomatique ( LETG ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Université d'Angers ( UA ) -Université de Nantes ( UN ) -École pratique des hautes études ( EPHE ) -Université de Brest ( UBO ) -Université de Rennes 2 ( UR2 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Caen Normandie ( UNICAEN ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Littoral, Environnement, Télédétection, Géomatique (LETG-Angers), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

Karst or dissolution geology can occur whenever a circulating fluid can dissolve a geological material. On Earth, the “classical” karst definition is for limestone (CaCO3) in water (H2O), but other material/solvent combinations can create terrestrial dissolution terrain as well. These include so-called “evaporite karst materials” such as halite (NaCl)/H2O or gypsum (CaSO4)/H2O, dolomite (CaMg(CO3)2)/H2O, and even silica (SiO2)/H2O [Ford and Williams, 2007]. On Mars, there has been the suggestion of kieserite (MgSO4)/H2O system that may have formed in an earlier, wetter environment [Baroni and Sgavetta, 2013].Saturn’s moon Titan extends the definition of karst to include non-aqueous liquids dissolving a landscape made of organic materials. The Cassini mission has provided evidence that Titan’s 1.5 bar nitrogen atmosphrere and cryogenic 94 K surface temperature supports a hydrocarbon-based cycle on Titan similar to the terrestrial water cycle. These circulating liquids may be capable of dissolving some of the surface organic molecules derived from Titan’s complex atmospheric photochemistry. Although under a different gravity, temperature, materials and fluid regime, many of the features on Titan’s surface bear striking resemblances to terrestrial karst terrains.Our investigations have focused on the labyrinth terrains of Titan. These are elevated plateaux of organic materials that appear similar to polygonal karst, tower karst, and fluviokarst on Earth [Malaska et al., 2010; 2017]. Remote sensing data is consistent with these plateaux being constructed of low-dielectric organic materials [Janssen et al. 2009; 2016; Malaska et al, 2016b]. Theoretical calculations followed by cryogenic laboratory experiments have shown that organic materials found on Titan’s surface will dissolve when subjected to Titan’s rainfall of methane-rich fluids [Raulin, 1987; Lorenz and Lunine, 1996; Malaska et al., 2010; 2011; Malaska and Hodyss, 2014; Cornet et al., 2015] and preliminary modelling has been able to reproduce some of the morphologies observed on Titan [Cornet et al., 2017].Titan’s labyrinth terrains may originate as mixed organic windblown sediments that are later lithified in a process similar to calcite-cemented sandstone on Earth. Organic molecules and sediments produced by Titan’s rich organic photochemistry include organic molecules such as acetylene (C2H2), ethylene (C2H4), hydrogen cyanide (HCN), benzene (C2H6), acrylonitrile (C2H3CN), acetonitrile (CH3CN), cyanoacetylene (HC2CN), other alkynes and nitriles, and a complex refractory organic materials similar to laboratory tholins. Once uplifted, the saturation equilibrium and kinetics of dissolution for each material and fluid combination affecting the plateau may play key roles in determining how the karstic system will evolve [Malaska et al., 2011; Cornet et al., 2015]. Some of the Titan organic minerals will dissolve, while some will be left behind as an insoluble lag deposit. Advanced laboratory investigations of organic materials on Titan is underway to further understand how these geological structures evolve and compare them with the formation processes of terrestrial analogs. We suggest that karst is a general planetary process wherever circulating fluids are capable of dissolving materials and developing subsurface drainage.

Published
2018

24. The Spectral Nature of Titan's Major Geomorphological Units

Author

Solomonidou, A., Coustenis, A., Lopes, R.M.C., Malaska, M. J., Rodriguez, S., Altobelli, N., Drossart, P., Elachi, Charles, Schmitt, B., Janssen, Michael A., Wall, S., Sotin, C., Lawrence, K.J., Radebaugh, J., Stephan, Katrin, Brown, Robert H., LeMouelic, Stephane, Le Gall, Alice, Witasse, Olivier, and Matsoukas, C.

Subjects
Planetengeologie, VIMS, Cassini, Titan
Published
2018

25. Titan's Major Geomorphological Units: Their Spectral and Morphological Nature

Author

Solomonidou, A., Coustenis, A., Drossart, P., Brown, Robert H., Stephan, Katrin, Altobelli, N., Sotin, C., Lawrence, K.J., Le Mouelic, S., Rodriguez, S., Schmitt, B., Le Gall, Alice, Elachi, Charles, Lopes, R.M.C., Witasse, Olivier, Radebaugh, J., Wall, S., Malaska, M. J., Janssen, M., and Matsoukas, C.

Subjects
Planetengeologie, VIMS, Cassini, Titan
Published
2018

26. The spectral nature of Titan's mid-latitude region

Author

Solomonidou, A., Coustenis, A., Lopes, R.M.C., Malaska, M. J., Rodriguez, S., Drossart, P., Schmitt, B., Philippe, S., Janssen, Michael A., Le Gall, A., Lawrence, K.J., Hirtzig, M., Sohl, Frank, Stephan, Katrin, Jaumann, Ralf, Brown, Robert H., Villanueva, Edward, Bratsolis, E., Matsoukas, C., Schoenfeld, A., Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut National de Recherche Pédagogique - La main à la pâte, INRP, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Department of Physics [Athens], National and Kapodistrian University of Athens (NKUA), Royal Institute of Technology [Stockholm] (KTH ), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), National and Kapodistrian University of Athens = University of Athens (NKUA | UoA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), NASA-California Institute of Technology (CALTECH), and Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112))

Subjects
[SDU]Sciences of the Universe [physics], VIMS, Cassini, Titan
Abstract

International audience; We infer surface properties, such as surface albedo and atmospheric contributions in the form of haze content, of the mid-latitude region of Titan. In previous studies [1;2] we reported results on two areas presenting indications for possible changes in surface albedo with time [2]. We also investigate the endogenic or exogenic processes linked to the formation of the various mid-latitude geomorphological units. These could be aeolian, fluvial, sedimentary, cryovolcanic, lacustrine, and more. Furthermore, deposition of organics through the atmosphere seems to be predominantly present [1]. We now focus on constraining the chemical composition of the various geomorphological units [5;6] by investigating the lower atmosphere of Titan from Visual and Infrared Mapping Spectrometer (VIMS) spectro-imaging data by use of a recently updated radiative transfer code in the near-IR range. For the distinction of geomorphological units we use RADAR/SAR data [4]. We study the units of interest identified in [1;3] and [4]: mountains, plains, labyrinths, dune fields, and possible cryovolcanic and/or evaporitic features (the latter two are albedo features, [4;5]). Our findings indicate that many of the regions from the same geomorphological unit show compositional variations depending on location, while units of significant geomorphological differences seem to consist of very similar material mixtures. Preliminary results on the chemical composition of the regions that have shown temporal changes (i.e. Tui Regio and Sotra Patera; [6]) are also presented. The albedo differences and similarities among the various geomorphological terrains set constraints on the possible geological processes that govern Titan's surface. References: [1] Lopes, R.M.C., et al.: Icarus, 270, 162-182, 2016; [2] Solomonidou, A., et al.: Icarus, 270, 85-99, 2016; [3] Lopes, R.M.C., et al.: Icarus, 205, 540-558, 2010; [4] Malaska, M., et al.: Icarus, 270, 130-161, 2016; [4] Barnes, J., et al.: Pl. Scie., 2:1, 2013; [5] Solomonidou, A., et al.: JGR, 119, 1729-1747, 2014; [6] Schmitt, B., et al.: GhoSST database (ghosst.osug.fr).

Published
2017

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

Author

Solomonidou, A., Coustenis, A., Lopes, R. M. C., Malaska, M. J., Rodriguez, S., Drossart, P., Elachi, C., Schmitt, B., Philippe, S., Janssen, M., Hirtzig, M., Wall, S., Sotin, C., Lawrence, K., Altobelli, N., Bratsolis, E., Radebaugh, J., Stephan, K., Brown, R. H., Le Mouelic, S., Le Gall, A., Villanueva, E. V., Brossier, J. F., Bloom, A. A., Witasse, O., Matsoukas, C., Schoenfeld, A., Solomonidou, A., Coustenis, A., Lopes, R. M. C., Malaska, M. J., Rodriguez, S., Drossart, P., Elachi, C., Schmitt, B., Philippe, S., Janssen, M., Hirtzig, M., Wall, S., Sotin, C., Lawrence, K., Altobelli, N., Bratsolis, E., Radebaugh, J., Stephan, K., Brown, R. H., Le Mouelic, S., Le Gall, A., Villanueva, E. V., Brossier, J. F., Bloom, A. A., Witasse, O., Matsoukas, C., and Schoenfeld, A.

Abstract

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 2.79m, 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 degrees N and 30 degrees 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. Plain Language Summary Titan, Saturn's moon, has been investigated by the Cassini mission for almost 13 years, unveiling an exotic world with many features similar to Earth. One of the mysteries that still has not been re, QC 20180404

Published
2018
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28. The Spectral Nature of Titan's Major Geomorphological Units: Constraints on Surface Composition

Author

Solomonidou, A., primary, Coustenis, A., additional, Lopes, R. M. C., additional, Malaska, M. J., additional, Rodriguez, S., additional, Drossart, P., additional, Elachi, C., additional, Schmitt, B., additional, Philippe, S., additional, Janssen, M., additional, Hirtzig, M., additional, Wall, S., additional, Sotin, C., additional, Lawrence, K., additional, Altobelli, N., additional, Bratsolis, E., additional, Radebaugh, J., additional, Stephan, K., additional, Brown, R. H., additional, Le Mouélic, S., additional, Le Gall, A., additional, Villanueva, E. V., additional, Brossier, J. F., additional, Bloom, A. A., additional, Witasse, O., additional, Matsoukas, C., additional, and Schoenfeld, A., additional

Published
2018
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29. Topographic Constraints on the Evolution and Connectivity of Titan's Lacustrine Basins

Author

Hayes, A. G., primary, Birch, S. P. D., additional, Dietrich, W. E., additional, Howard, A. D., additional, Kirk, R. L., additional, Poggiali, V., additional, Mastrogiuseppe, M., additional, Michaelides, R. J., additional, Corlies, P. M., additional, Moore, J. M., additional, Malaska, M. J., additional, Mitchell, K. L., additional, Lorenz, R. D., additional, and Wood, C. A., additional

Published
2017
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30. Raised Rims Around Titan's Sharp‐Edged Depressions.

Author

Birch, S. P. D., Hayes, A. G., Poggiali, V., Hofgartner, J. D., Lunine, J. I., Malaska, M. J., Wall, S., Lopes, R. M. C., and White, O.

Subjects
SURVEYS, RADAR indicators, MENTAL depression, GEOLOGY
Abstract

We perform a systematic survey of Titan's sharp‐edged depressions (SEDs) using a combination of Cassini synthetic aperture radar images and delay‐Doppler processed altimetry. We identify a characteristic bright‐dark pattern around 172 SEDs that correlates with elevated features only resolved with the highest resolution topographic data. We find that ∼75% of Titan's SEDs have elevated (∼100 m) rim features, with a preference toward larger SEDs. The differences in the distribution of SED rim presence between the north and south are slight, but the data weakly suggest that northern SEDs may be more likely to have a rim. The pattern we identify in synthetic aperture radar images is similar to quasi‐specular increases in backscatter seen on Titan's dunes. We show that this bright‐dark pattern occurs due to elevated local slopes oriented perpendicular to the radar. In general, rims occur on most of Titan's SEDs, an observation that will aid in developing and testing SED formation models. Plain Language Summary: Though they contain <1% of Titan's current liquids, Titan's sharp‐edged depressions (SEDs) are important geologic features whose formation and evolution may trace that of the polar regions as a whole. Distributed across both polar regions, these SEDs appear as closed depressions, in both a liquid‐filled and empty state. Our study uses high‐resolution topographic data and synthetic aperture radar image data to identify 100‐m‐high raised rims around most (75%) of these features. The origin of these features is not immediately clear. While the favored model for the formation of SEDs is dissolution erosion, dissolution is incompatible with the presence of these elevated rims. Our observations, though they add complications to current formation models, add an additional piece of information for future models to use as they continue to develop. Key Points: Raised rims are observable in SAR images and correlate with topographic highsMost sharp‐edged depressions (75%) have 100‐m raised rimsRim presence appears to depend on sharp‐edged depression size [ABSTRACT FROM AUTHOR]

Published
2019
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31. Changes on Titan’s surface

Author

Solomonidou, A., Lopes, R.M.C., Coustenis, A., Malaska, M. J., Sotin, C., Rodriguez, S., Janssen, M., Drossart, Pierre, Lawrence, K.J., Matsoukas, C., Hirtzig, M., Mouélic, S. Le, Jaumann, Ralf, Brown, Robert H., and Bratsolis, E.

Subjects
Planetengeologie, surface, Cassini, Titan
Published
2015

32. Cassini VIMS and RADAR investigation of Titan’s equatorial regions: a case for changes in surface properties

Author

Solomonidou, Anezina, Coustenis, A., Lopes, R.M.C., Rodriguez, S., Hirtzig, M., Malaska, M. J., Stephan, Katrin, Sotin, C., Drossart, P., Jaumann, R., Bratsolis, E., Mouélic, S. Le, Brown, Robert H., Henry, Florence, Jet Propulsion Laboratory, California Institute of Technology (JPL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Fondation La main à la pâte, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institute of Planetary Research, DLR, Rutherfordstrasse 2, D-12489 Berlin, Germany, National and Kapodistrian University of Athens (NKUA), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, United States

Subjects
Planetengeologie, VIMS, Cassini, surface properties, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Titan, RADAR
Abstract

International audience; The Cassini-Huygens instruments revealed that Titan, Saturn's largest moon, has - in many aspects - a complex, dynamic and Earth-like surface [1;2;3]. Understanding the distribution and interplay of geologic processes on Titan is important for constraining models of its interior, surface-atmosphere interactions, and climate evolution. Data from the remote sensing instruments have shown the presence of diverse terrains, suggesting exogenic and endogenic processes, whose composition remains largely unknown. Interpreting surface features further requires precise knowledge of the contribution by the dense intervening atmosphere, especially the troposphere, which can be recovered from near-IR data such as those collected by Cassini's Visual and Infrared Mapping Spectrometer (VIMS) collects in the so-called "methane windows". In order to simulate the atmospheric contribution and extract surface information, a statistical tool (PCA) and a radiative transfer code are applied on certain regions of interest (i.e. possibly geologically varying and suggested in some cases to be cryovolcanic and/or evaporitic in origin) [4;5;7]. We also analyze RADAR despeckled SAR images in terms of morphology [6]. For comparison, we also look at undifferentiated plains and dune fields regions that are not expected to change with time. We find that Tui Regio and Sotra Patera change with time becoming darker and brighter respectively in terms of surface albedo while the plains and the suggested evaporitic areas in the equatorial regions do not present any significant change [5]. The surface brightening of Sotra supports a possible internal rather than exogenic origin. The unchanged surface behavior of the plains supports a sedimentary origin rather than cryovolcanic. Preliminary results on the chemical composition of the changed regions with time are also presented. We therefore suggest that temporal variations of surface albedo (in chemical composition and/or morphology) exist for some areas on Titan, but that their origin may differ from one region to the other. Such a variety of geologic processes and their relationship to the methane cycle make Titan particularly significant in Solar System studies. References: [1] Lopes, R.M.C., et al.: JGR, 118, 416-435, 2013 [2] Solomonidou, A., et al.: PSS, 70, 77-104, 2013 [3] Moore, J.M., and Howard, A.D.: GRL, 37, L22205, 2010; [4] Solomonidou, A., et al.: JGR, 119, 1729-1747, 2014; [5] Solomonidou, A., et al.: Icarus, submitted, 2015; [6] Bratsolis, E., et al.: PSS, 61, 108-113, 2012; [7] Hirtzig, M., et al.: Icarus, 226, 470-486, 2013.

Published
2015

33. Titan’s mid-latitude surface regions with Cassini VIMS and RADAR

Author

Solomonidou, A., Lopes, R.M.C., Coustenis, A., Malaska, M., Rodriguez, S., Maltagliati, L., Drossart, Pierre, Janssen, M., Lawrence, K.J., Jaumann, Ralf, Sohl, F., Stephan, K., Brown, Robert H., Bratsolis, E., and Matsoukas, C.

Subjects
Planetengeologie, Planetenphysik, VIMS, CASSINI, Titan, RADAR
Published
2015

34. The spectral evolution of various Titan geomorphic surface types

Author

Solomonidou, A., Coustenis, A., Lopes, R.M.C., Rodriguez, S., Malaska, M. J., Drossart, Pierre, Sotin, C., Lawrence, K.J., Hirtzig, M., Mouélic, S. Le, Stephan, K., Jaumann, Ralf, Maltagliati, L., and Brown, Robert H.

Subjects
Planetengeologie, surface, Cassini, Titan
Published
2015

36. Thermo-mechanical behaviour of ground-source thermo-active structures

Author

Kujala, K. (Kauko), Malaska, M. (Mikko), Hassani Nezhad Gashti, E. (Ehsan), Kujala, K. (Kauko), Malaska, M. (Mikko), and Hassani Nezhad Gashti, E. (Ehsan)

Abstract

High energy prices and new environmental policies have made geothermal energy increasingly popular. The EU, including Finland, aims to increase the use of renewable energy resources and reduce carbon emissions. Geothermal energy pile foundations, so-called energy piles, are considered a viable alternative technology for producing energy instead of traditional methods. Geothermal heat pump systems are economically efficient and renewable environmentally friendly energy production systems in which the ground acts as a heat source in winter and as a heat sink in summer. Energy piles are economical systems, as they act as dual-purpose structures in energy production and load transfer from buildings to the ground, avoiding extra expenses in ground boring solely for energy production. However, use of ground heat exchangers (GHE) for energy production in energy piles can result in temperature variations in the pile shaft and surrounding soil, in turn affecting the thermo-mechanical behaviour of pile shaft and soil in both structural and geotechnical terms. Despite large numbers of energy piles being installed, there is still a lack of reliable information and experience about the thermo-mechanical behaviour of these structures and their energy efficiency in cold climates. This thesis investigated the efficiency performance of energy pile foundations and their productivity in cold climates by considering different groundwater flow effects and short-term imbalanced seasonal thermal loadings. The structural and geotechnical bearing capacity of different types of energy piles fitted with GHEs were also evaluated, using numerical models, and the possibility of collapse due to use of thermal systems was examined. Use of the model to compare the performance of different GHEs in terms of their efficiency revealed that at a particular fluid flow rate, double U-tube systems had greater productivity than other systems tested. The results also indicated that using energy pile, Tiivistelmä Kasvaneet energiakustannukset ja kiristyneet ympäristösäädökset ovat lisänneet geotermisten energiaratkaisujen suosiota. EU, mukaan lukien Suomi, on asettanut tavoitteekseen lisätä uusiutuvien energialähteiden käyttöä ja vähentää hiilidioksidipäästöjä. Geotermistä energiaa hyödyntävä paaluperustukset, niin kutsutut energiapaalut, tarjoavat uudenlaisen teknologian vähäpäästöisen energian tuottamiseen. Geotermiset lämpöpumppujärjestelmät, maalämpöpumput, ovat taloudellisia ja ympäristöystävällisiä energiantuotantomenetelmiä, jotka talviaikaan siirtävät maaperään varastoitunutta energiaa rakennuksen lämmittämiseen ja vastaavasti jäähdyttävät rakennusta kesällä siirtämällä lämpöä maaperään. Energiapaalujen taloudellisuus syntyy siitä, että ne pystyvät palvelemaan rakennusta kahdessa roolissa. Ne ovat osa rakennuksen energiajärjestelmää ja toimivat samalla myös kantavana rakenteena, joka siirtää rakennuksen kuormia perustuksilta maaperään. Lämpöpumppujärjestelmän kytkeminen paaluihin voi johtaa lämpötilan vaihteluun paaluissa sekä niitä ympäröivässä maaperässä, mikä puolestaan vaikuttaa paalujen ja maaperän lämpömekaanisiin, rakenteellisiin sekä geoteknisiin ominaisuuksiin. Vaikka energiapaaluja on asennettu jo paljon, ei paalujen lämpömekaanisesta käyttäytymisestä tai energiatehokkuudesta kylmien ilmastojen alueilla ole vielä paljoa tutkittua tietoa. Tässä väitöstutkimuksessa selvitettiin numeerisesti energiapaalujen rakennuspaikan pohjaolosuhteista riippuvaa tuottopotentiaalia Skandinaavisissa olosuhteissa ja ilmastossa. Tarkastelut kohdistuivat erityisesti pohjavesivirtauksen sekä vuodenaikojen ja ilman lämpötilan vaihtelun vaikutuksiin. Tutkimuksessa arvioitiin myös paalujen lämpötilan vaihtelujen vaikutuksia paalujen geoteknisiin ja rakenteellisiin ominaisuuksia sekä kestävyyteen. Numeeristen simulaatiotulosten perusteella betonipaaluun asennetun U-putkirakenteen avulla saavutetaan paras tuottopotentiaali. Tulokset osoittivat, että kohtalainen pohjaveden

Published
2016

37. Composition, seasonal change, and bathymetry of Ligeia Mare, Titan, derived from its microwave thermal emission

Author

Le Gall, A., Malaska, M. J., Lorenz, R. D., Janssen, M. A., Tokano, T., Hayes, A. G., Mastrogiuseppe, M., Lunine, J. I., Veyssiere, G., Encrenaz, P., Karatekin, O., Le Gall, A., Malaska, M. J., Lorenz, R. D., Janssen, M. A., Tokano, T., Hayes, A. G., Mastrogiuseppe, M., Lunine, J. I., Veyssiere, G., Encrenaz, P., and Karatekin, O.

Abstract

For the last decade, the passive radiometer incorporated in the Cassini RADAR has recorded the 2.2cm wavelength thermal emission from Titan's seas. In this paper, we analyze the radiometry observations collected from February 2007 to January 2015 over one of these seas, Ligeia Mare, with the goal of providing constraints on its composition, bathymetry, and dynamics. In light of the depth profile obtained by Mastrogiuseppe et al. (2014) and of a two-layer model, we find that the dielectric constant of the sea liquid is <1.8, and its loss tangent is 3.6-2.1+4.3x10-5. Both results point to a composition dominated by liquid methane rather than ethane. A high methane concentration suggests that Ligeia Mare is primarily fed by methane-rich precipitation and/or ethane has been removed from it (e.g., by crustal interaction). Our result on the dielectric constant of the seafloor is less constraining

Published
2016

38. Unveiling Titan’s Mid-Latitude Surface Regions

Author

Solomonidou, A., Coustenis, A., Lopes, R.M.C., Rodriguez, S., Hirtzig, M., Stephan, K., Sotin, C., Drossart, P., Le Mouelic, S., Lawrence, K.J., Malaska, M. J., Jaumann, R., Brown, Robert H., and Bratsolis, E.

Subjects
Titan
Published
2014

39. The Case of Titan's Mysterious New Island: Analysis of Anomalously Bright Features Observed in the Cassini T92 SAR Pass Over Titan's Ligeia Mare

Author

Hofgartner, J. D., Hayes, A. G., Lunine, J.I., Zebker, H., Stiles, B., Sotin, C., Barnes, J.W., Brown, B. H., Encrenaz, P., Kirk, R. D., Le Gall, Alice, Lopes, R. M., Lorenz, R. D., Malaska, M., Mitchell, K. L., Paillou, Philippe, Radebaugh, J., Turtle, E., Wall, S., Wood, C., Pomies, Marie-Paule, Department of Astronomy [Ithaca], Cornell University [New York], Department of Electrical Engineering [Stanford], Stanford University, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Physics [Moscow,USA], University of Idaho [Moscow, USA], University of Arizona, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), SSE 2014, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Department of Geological Sciences [BYU], Brigham Young University (BYU), Planetary Science Institute [Tucson] (PSI), Cassini Radar, École normale supérieure - Paris (ENS-PSL), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB)

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; Anomalous features were detected in Ligeia Mare that were not in any preceding nor subsequent observations. They are unique on Titan or transient in nature.

Published
2014

40. Titan's 'blandlands': Are they massive sand sheets?

Author

Lopes, R. M., Malaska, M. J., Le Gall, A. A., Hayes, A., Samuel Birch, Mitchell, K. L., Kirk, R. L., Radebaugh, J., Neish, C., Lucas, A., Lorenz, R. D., Janssen, M. A., Stofan, E. R., Wall, S., Lunine, J. I., Ewing, R. C., Barnes, J. W., Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy [Ithaca], Cornell University [New York], Department of Mathematics [Berkeley], University of California [Berkeley], University of California-University of California, Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), Department of Geological Sciences [BYU], Brigham Young University (BYU), Florida Institute of Technology [Melbourne], Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Proxemy Research Inc, Texas A&M University [College Station], Department of Physics [Moscow,USA], University of Idaho [Moscow, USA], Cardon, Catherine, University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), California Institute of Technology (CALTECH)-NASA, IMPEC - LATMOS, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Cornell University

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

The undifferentiated plains first mapped by Lopes et. al. (2010, Icarus 205) are vast expanses of terrains that appear bland in Cassini RADAR Synthetic Aperture Radar images, hence the designation 'blandlands'. While the interpretation of several other geologic units on Titan, such as dunes and well-preserved impact craters, has been relatively straightforward, the origin of the 'blandlands' has remained mysterious. SAR images show that the 'blandlands' are mostly found at mid-latitudes and appear relatively featureless at radar wavelengths, with no significant topography. Their gradational boundaries and paucity of features in SAR data make geologic interpretation particularly challenging. We have mapped the distribution of these terrains using SAR swaths up to T92, which cover > 50% of Titan's surface. We compared SAR images with their de-noised counterparts (Lucas et. al.,2001, AGU Fall Meeting), the topography using SARTopo method (Stiles et. al., 2009, Icarus 202) and, where possible, the response from radiometry. We examined and evaluated different formation mechanisms. Previous work (Lopes et. al., AGU, 2012) proposed that plains were either (i) sedimentary in origin, resulting from fluvial or lacustrine deposition or accumulation of photolysis products created in the upper atmosphere or (ii) cryovolcanic in origin, consisting of overlapping flows of low relief, obscured by accumulation of sediments. The results from our analysis suggest that the sedimentary origin is the most likely, and that plains materials are similar or the same as dune materials. Plains occur mostly at mid-latitudes, while dunes occur mostly at low latitudes. This may be a result of wind patterns, decrease in sand supply, or changes in properties of sand, perhaps moisture content, all of which would inhibit the formation of large dunes.

Published
2013

41. Cryovolcanism on Titan: New results from Cassini RADAR and VIMS

Author

Lopes, Rosaly M. C., Kirk, Randolph L., Mitchell, Karl L., Le Gall, Alice, Barnes, Jason W., Hayes, A., Kargel, J., Wye, L., Radebaugh, J., Stofan, E. R., Janssen, M. A., Neish, Catherine D., Wall, S. D., Wood, C. A., Lunine, J.I., Malaska, M. J., Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Idaho [Moscow, USA], Department of Astronomy [Ithaca], Cornell University [New York], Department of Hydrology and Atmospheric Sciences [University of Arizona], University of Arizona, Department of Electrical Engineering [Stanford], Stanford University, Department of Geological Sciences [BYU], Brigham Young University (BYU), Proxemy Research Inc, NASA Goddard Space Flight Center (GSFC), Planetary Science Institute [Tucson] (PSI), NASA, and Department of Hydrology and Water Resources

Subjects
Volcanism, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Titan, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; The existence of cryovolcanic features on Titan has been the subject of some controversy. Here we use observations from the Cassini RADAR, including Synthetic Aperture Radar (SAR) imaging, radiometry, and topographic data as well as compositional data from the Visible and Infrared Mapping Spectrometer (VIMS) to reexamine several putative cryovolcanic features on Titan in terms of likely processes of origin (fluvial, cryovolcanic, or other). We present evidence to support the cryovolcanic origin of features in the region formerly known as Sotra Facula, which includes the deepest pit so far found on Titan (now known as Sotra Patera), flow-like features (Mohini Fluctus), and some of the highest mountains on Titan (Doom and Erebor Montes). We interpret this region to be a cryovolcanic complex of multiple cones, craters, and flows. However, we find that some other previously supposed cryovolcanic features were likely formed by other processes. Cryovolcanism is still a possible formation mechanism for several features, including the flow-like units in Hotei Regio. We discuss implications for eruption style and composition of cryovolcanism on Titan. Our analysis shows the great value of combining data sets when interpreting Titan's geology and in particular stresses the value of RADAR stereogrammetry when combined with SAR imaging and VIMS.

Published
2013
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42. Titan's Plains: Global Distribution and Possible Origin

Author

Lopes, R. M., Alice Le Gall, Kirk, R. L., Kargel, J. S., Stofan, E. R., Mitchell, K. L., Antoine Lucas, Janssen, M. A., Wall, S. D., Malaska, M. J., Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), University of Arizona, Proxemy Research Inc, California Institute of Technology (CALTECH), and Cardon, Catherine

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; Titan's diverse and Earth-like geologic features have been mapped and interpreted based on their morphological characteristics (Lopes et al., 2010, Icarus 205; Aharonson et al., 2012, Titan: Surface, Atmosphere, Magnetosphere, Cambridge University Press). While the interpretation for the origin of some units, such as dunes and well-preserved impact craters, has been relatively straightforward, others have been more challenging. In particular, the undifferentiated plains first mapped by Lopes et al. (2010) remain mysterious. These vast expanses, mostly found at mid-latitudes are relatively featureless and appear to have low relief. Their gradational boundaries and paucity of features in SAR data make geologic interpretation particularly difficult using only this dataset. Plains may be sedimentary in origin, resulting from fluvial or lacustrine deposition or accumulation of photolysis products created in the upper atmosphere. Alternatively, the plains may be cryovolcanic, consisting of overlapping flows of low relief, obscured by accumulation of sediments. In this paper, we use SAR, radiometry, scatterometry, and SARTopo data to examine the characteristics of the plains and compare them with other geologic units. We also compare their global distribution with that of other units and examine the implications of a possible cryovolcanic origin.

Published
2012

43. Coexistence of Dunes and Humid Conditions at Titan's Tropics

Author

Radebaugh, Jani, Lorenz, R. D., Lunine, J.I., Kirk, R. L., Ori, G. G., Farr, T. G., Malaska, M., Le Gall, Alice, Liu, Z. Y. C., Encrenaz, P. J., Paillou, Philippe, Hayes, A., Lopes, R. M. C., Turtle, E. P., Wall, S. D., Stofan, E. R., Wood, C. A., Department of Geological Sciences [BYU], Brigham Young University (BYU), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Department of Astronomy [Ithaca], Cornell University [New York], Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), SSE 2012, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Proxemy Research Inc, Wheeling Jesuit University, Cassini Radar, Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB)

Subjects
[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; At Titan's equatorial latitudes there are tens of thousands of dunes, a landform typical of desert environments where sand does not become anchored by vegetation or fluids. Model climate simulations predict generally dry conditions at the equator and humid conditions near the poles of Titan, where lakes of methane/ethane are found. However, moderate relative methane humidity was observed at the Huygens landing site, recent rainfall was seen by Cassini ISS near the Belet Sand Sea, and a putative transient lake in Shangri-La was observed by Cassini VIMS, all of which indicate abundant fluids may be present, at least periodically, at Titan's equatorial latitudes. Terrestrial observations and studies demonstrate dunes can exist and migrate in conditions of high humidity. Active dunes are found in humid climates, indicating the movement of sand is not always prohibited by the presence of fluids. Sand mobility is related to precipitation, evaporation and wind speed and direction. If dune surfaces become wetted by rainfall or rising subsurface fluids, they can become immobilized. However, winds can act to dry the uppermost layers, freeing sands for saltation and enabling dune migration in wet conditions. Active dunes are found in tropical NE Brazil and NE Australia, where there are alternating dry and wet periods, a condition possible for Titan's tropics. Rising and falling water levels lead to the alteration of dune forms, mainly from being anchored by vegetation, but also from cementation by carbonates or clays. Studies of Titan's dunes, which could undergo anchoring of organic sediments by hydrocarbon fluids, could inform the relative strength of vegetation vs. cementation at humid dune regions on Earth. Furthermore, a comprehensive survey of dune morphologies near regions deemed low by SARTopo and stereo, where liquids may collect in wet conditions, could reveal if bodies of liquid have recently existed at Titan's tropics.

Published
2012

44. Dark and Bright Albedo Changes in the Wake of a Titan Rainstorm

Author

Barnes, Jason W., Buratti, B. J., Turtle, E. P., Bow, J., Dalba, P. A., Perry, J., Rodriguez, S., LeMouelic, S., Baines, K. H., Sotin, C., Lorenz, R. D., Malaska, M. J., McCord, T. B., Clark, R. N., Jaumann, R., Hayne, P. O., Nicholson, P. D., Soderblom, J. M., and Soderblom, L. A.

Subjects
Albedo, ISS, VIMS, Cassini, Titan
Published
2012

47. Spectral properties of Titan's impact craters imply chemical weathering of its surface

Author

Neish, C. D., primary, Barnes, J. W., additional, Sotin, C., additional, MacKenzie, S., additional, Soderblom, J. M., additional, Le Mouélic, S., additional, Kirk, R. L., additional, Stiles, B. W., additional, Malaska, M. J., additional, Le Gall, A., additional, Brown, R. H., additional, Baines, K. H., additional, Buratti, B., additional, Clark, R. N., additional, and Nicholson, P. D., additional

Published
2015
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49. Transient features in a Titan sea

Author

Hofgartner, J. D., primary, Hayes, A. G., additional, Lunine, J. I., additional, Zebker, H., additional, Stiles, B. W., additional, Sotin, C., additional, Barnes, J. W., additional, Turtle, E. P., additional, Baines, K. H., additional, Brown, R. H., additional, Buratti, B. J., additional, Clark, R. N., additional, Encrenaz, P., additional, Kirk, R. D., additional, Le Gall, A., additional, Lopes, R. M., additional, Lorenz, R. D., additional, Malaska, M. J., additional, Mitchell, K. L., additional, Nicholson, P. D., additional, Paillou, P., additional, Radebaugh, J., additional, Wall, S. D., additional, and Wood, C., additional

Published
2014
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