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104 results on '"Lopes, R. M. C."'

1. The temporal variability of Io's hotspots.

Author

Mura, A., Zambon, F., Tosi, F., Lopes, R. M. C., Rathbun, J., Pettine, M., Adriani, A., Altieri, F., Ciarniello, M., Cicchetti, A., Filacchione, G., Grassi, D., Noschese, R., Migliorini, A., Piccioni, G., Plainaki, C., Sordini, R., Sindoni, G., Turrini, D., and Radebaugh, Jani

Subjects
INFRARED imaging, INFRARED spectra, JUPITER (Planet), AURORAS, ORBITS (Astronomy)
Abstract

We investigate the variability of the power emission of Io's hotspots by using recent Juno/JIRAM infrared observations. The Jovian Infrared Auroral Mapper (JIRAM) is an imaging spectrometer which began observing Jupiter in August 2016. Although observing Jupiter's moons is not its primary objective, JIRAM can use the frequent opportunities to observe Io (up to once per orbit) to gather infrared images and spectra of its surface. The present study uses the data acquired by JIRAM during the last 2 years, including the location and morphology of Io's hotspots, and the temporal variability of the total output. A new photometric model for the hotspots and the dayside surface has been developed, which permits us to disentangle the temporal variability from the changes in the observation geometry. While the latitudinal dependence of the power output is not well constrained, low-latitude hotspots show a significantly more intense temporal variability and greater temperature. [ABSTRACT FROM AUTHOR]

Published
2024
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2. JIRAM Observations of Volcanic Flux on Io: Distribution and Comparison to Tidal Heat Flow Models.

Author

Pettine, M., Imbeah, S., Rathbun, J., Hayes, A., Lopes, R. M. C., Mura, A., Tosi, F., Zambon, F., and Bertolino, S.

Subjects
GRAVITATIONAL interactions, INFRARED cameras, SOLAR system, VOLCANOES, HARMONIC analysis (Mathematics)
Abstract

Juno has allowed clear, high‐resolution imaging of Io's polar volcanoes using the Jovian Infrared Auroral Mapper (JIRAM) instrument. We have used data from JIRAM's M‐band (4.78 μm) imager from 11 Juno orbits to construct a global map of volcanic flux. This map provides short‐term insight into the spatial distribution of volcanoes and the ways in which high‐ and low‐latitude volcanoes differ. Using spherical harmonic analysis, we quantitatively compare our volcanic flux map to the surface heat flow distribution expected from models of Io's tidal heat deposition (summarized in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82). Our observations confirm previously detected systems of bright volcanoes at high latitudes. Our study finds that both poles are comparably active and that the observed flux distribution is inconsistent with an asthenospheric heating model, although the south pole is viewed too infrequently to establish reliable trends. Plain Language Summary: Our study uses data from an infrared camera on Juno called the Jovian Infrared Auroral Mapper (JIRAM) to image Io, the innermost Galilean moon of Jupiter. Io is the most volcanically active body in the Solar System. Io's volcanoes are powered by both the extreme tides from Jupiter and the gravitational interactions between it and Jupiter's other moons. These tides generate friction inside Io. Simulations of Io's interior suggest that, depending on how deep that friction is being generated, the surface heat flow will be higher in certain areas (de Kleer, Park, et al., 2019, https://doi.org/10.26206/d4wc‐6v82). Using JIRAM, we have mapped where volcanoes are producing the most power and compared that to where we expect higher heat flow from the interior models. Our map doesn't agree with any of these models very well. JIRAM observed more volcanic activity at the poles than we expected to see based on previous observations. However, since the south pole was only observed twice, it's possible that these observations don't represent the average volcanic activity of the south pole. Very bright volcanoes that may have been continuously active for decades were also imaged during these Juno fly‐bys, some of which are nearer the poles than the equator. Key Points: We have produced a global volcanic flux map of Io using data from 11 Juno fly‐bysOur flux map doesn't agree well with tidal heat flow models reported in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82)The M‐band flux is anti‐correlated with the asthenospheric heating model and has only very weak agreement with the global magma ocean model [ABSTRACT FROM AUTHOR]

Published
2024
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5. 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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6. Io Hot Spot Distribution Detected by Juno/JIRAM

Author

Zambon, F., primary, Mura, A., additional, Lopes, R. M. C., additional, Rathbun, J., additional, Tosi, F., additional, Sordini, R., additional, Noschese, R., additional, Ciarniello, M., additional, Cicchetti, A., additional, Adriani, A., additional, Agostini, L., additional, Filacchione, G., additional, Grassi, D., additional, Piccioni, G., additional, Plainaki, C., additional, Sindoni, G., additional, Turrini, D., additional, Brooks, S., additional, Hansen‐Koharcheck, C., additional, and Bolton, S., additional

Published
2023
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7. 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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8. Corrigendum: The temporal variability of Io's hotspots.

Author

Mura, A., Zambon, F., Tosi, F., Lopes, R. M. C., Rathbun, J., Pettine, M., Adriani, A., Altieri, F., Ciarniello, M., Cicchetti, A., Filacchione, G., Grassi, D., Noschese, R., Migliorini, A., Piccioni, G., Plainaki, C., Sordini, R., Sindoni, G., and Turrini, D.

Subjects
JUNO (Space probe), JUPITER (Planet), AURORAS, REFERENCE books, PUBLISHED articles
Abstract

The document is a corrigendum for an article on Io's hotspots, correcting references to various studies and authors. The corrections ensure accurate citations and do not impact the scientific conclusions of the original article. The authors are from various institutions in Italy, the United States, and other countries, emphasizing international collaboration in space research. [Extracted from the article]

Published
2024
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9. Titan's Cold Case Files - Outstanding Questions After Cassini-Huygens

Author

Nixon, C. A, Lorenz, R. D, Achterberg, R. K, Buch, A, Coll, P, Clark, R. N, Courtin, R, Hayes, A, Less, L, Johnson, R. E, Lopes, R. M. C, Mastrogiuseppe, M, Mandt, K, Mitchell, D. G, Raulin, F, Rymer, A. M, Todd Smith, H, Solomonidou, A, Sotin, C, Turtle, E. P, Vuitton, V, West, R. A, and Yelle, R. V

Subjects
Lunar And Planetary Science And Exploration
Abstract

The entry of the Cassini-Huygens spacecraft into orbit around Saturn in July 2004 marked the start of a golden era in the exploration of Titan, Saturn's giant moon. During the prime mission (2004-2008), ground-breaking discoveries were made by the Cassini orbiter including the equatorial dune fields (flyby T3, 2005), northern lakes and seas (T16, 2006), and the large positive and negative ions (T16 & T18, 2006), to name a few. In 2005 the Huygens probe descended through Titan's atmosphere, taking the first close-up pictures of the surface, including large networks of dendritic channels leading to a dried-up seabed, and also obtaining detailed profiles of temperature and gas composition during the atmospheric descent. The discoveries continued through the Equinox mission (2008-2010) and Solstice mission (2010-2017) totaling 127 targeted flybys of Titan in all. Now at the end of the mission, we are able to look back on the high-level scientific questions from the start of the mission, and assess the progress that has been made towards answering these. At the same time, new scientific questions regarding Titan have emerged from the new discoveries that have been made. In this paper we review a cross-section of important scientific questions that remain partially or completely unanswered, ranging from Titan's deep interior to the exosphere. Our intention is to help formulate the science goals for the next generation of planetary missions to Saturn and Titan, and to stimulate new experimental, observation and theoretical investigations in the interim, before such missions arrive again at Titan.

Published
2018
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12. Io's Atmospheric Response to Eclipse: UV Aurorae Observations

Author

Retherford, K. D., Spencer, J. R., Stern, S. A., Saur, J., Strobel, D. F., Steffl, A. J., Gladstone, G. R., Weaver, H. A., Cheng, A. F., Parker, J. Wm., Slater, D. C., Versteeg, M. H., Davis, M. W., Bagenal, F., Throop, H. B., Lopes, R. M. C., Reuter, D. C., Lunsford, A., Conard, S. J., Young, L. A., and Moore, J. M.

Published
2007
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14. 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

15. 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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16. 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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17. The science enabled by a dedicated solar system space telescope

Author

Young, Cindy, primary, Wong, M. H., additional, Sayanagi, K. M., additional, Curry, S., additional, Jessup, K. L., additional, Becker, T., additional, Hendrix, A., additional, Chanover, N., additional, Milam, S., additional, Holler, B. J., additional, Holsclaw, G., additional, Peralta, J., additional, Clarke, J., additional, Spencer, J., additional, Kelley, M. S. P., additional, Luhmann, J., additional, MacDonnell, D., additional, Jr., R. J. Vervack,, additional, Rutherford, K., additional, Fletcher, L. N., additional, Pater, I. de, additional, Vilas, F., additional, Feaga, L., additional, Siegmund, O., additional, Bell, J., additional, Delory, G., additional, Pitman, J., additional, Greathouse, T., additional, Wishnow, E., additional, Schneider, N., additional, Lillis, R., additional, Colwell, J., additional, Bowman, L., additional, Lopes, R. M. C., additional, McGrath, M., additional, Marchis, F., additional, Cartwright, R., additional, and Poston, M. J., additional

Published
2021
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18. Mapping Io's Surface Composition With Juno/JIRAM

Author

Tosi, F., primary, Mura, A., additional, Lopes, R. M. C., additional, Filacchione, G., additional, Ciarniello, M., additional, Zambon, F., additional, Adriani, A., additional, Bolton, S. J., additional, Brooks, S. M., additional, Noschese, R., additional, Sordini, R., additional, Turrini, D., additional, Altieri, F., additional, Cicchetti, A., additional, Grassi, D., additional, Hansen, C. J., additional, Migliorini, A., additional, Moriconi, M. L., additional, Piccioni, G., additional, Plainaki, C., additional, and Sindoni, G., additional

Published
2020
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19. 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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22. Mapping of the Culann-Tohil Region of Io

Author

Turtle, E. P, Keszthelyi, L. P, Jaeger, W. L, Radebaugh, J, Milazzo, M. P, McEwen, A. S, Moore, J. M, Schenk, P. M, and Lopes, R. M. C

Subjects
Lunar And Planetary Science And Exploration
Abstract

The Galileo spacecraft completed its observations of Jupiter's volcanic moon Io in October 2001 with the orbit I32 flyby, during which new local (13-55 m/pixel) and regional (130-400 m/pixel) resolution images and spectroscopic data were returned of the antijovian hemisphere. We have combined a I32 regional mosaic (330 m/pixel) with lower-resolution C21 color data (1.4 km/pixel, Figure 1) and produced a geomorphologic map of the Culann-Tohil area of this hemisphere. Here we present the geologic features, map units, and structures in this region, and give preliminary conclusions about geologic activity for comparison with other regions to better understand Io's geologic evolution.

Published
2003

23. Io's Thermal Regions and Non-SO2 Spectral Features

Author

Smythe, W. D, Soderblom, L. A, and Lopes, R. M. C

Subjects
Lunar And Planetary Science And Exploration
Abstract

Several absorptions have been identified in the Galileo NIMS spectra of Io that are not related to SO2. [1,2]. These absorptions have band centers at 2.97, 3.15, 3.85, and 3.91 microns. There are also broad absorptions in the regions 1-1.3 and 3- 3.4 microns. Patterning noise in wavelength registration, arising from the pushbroom imaging and grating motion of the NIMS instrument have previously inhibited reliable mapping of weak absorptions. Recent improvements in techniques to remove the coherent pattern noise from the NIMS dataset have been made by Soderblom. This greatly improves the signal to noise ratio and enables mapping of weak spectral signatures such as the 3.15 micron absorption on Io.

Published
2003

27. Io's diverse styles of volcanic activity: Results from Galileo NIMS

Author

Lopes, R. M. C, Smythe, W. D, Kamp, L. W, Doute, S, Carlson, R, McEwen, A. S, and Geissler, P. E

Abstract

The Near-Infrared Mapping Spectrometer on Galileo has observed Io since June 1996. In 1999 and 2000, the spacecraft made three close fly-bys to Io, revealing for the first time, the detailed thermal structure of some of Io's hot spots.

Published
2001

28. 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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29. 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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30. 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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31. 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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32. Alluvial Fans on Titan Reveal Materials, Processes and Regional Conditions

Author

Radebaugh, J., Lorenz, R. D., Farr, T. G., Kirk, Randolf L., Lunine, J.I., Ventra, D., Le Gall, Alice, Lopes, R. M. C., Barnes, Jason W., Hayes, A. G., Stofan, E. R., Wall, S. D., Wood, C., Cardon, Catherine, Department of Geological Sciences [BYU], Brigham Young University (BYU), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), Department of Astronomy [Ithaca], Cornell University [New York], Utrecht University [Utrecht], 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], Proxemy Research Inc, and Wheeling Jesuit 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], food and beverages, [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], human activities
Abstract

International audience; Alluvial fans on Titan reveal vigorous fluvial processes occur or occurred, indicate a prolonged depositional history, and may illuminate climate conditions.

Published
2013

33. 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

34. Titan's Dunes by the Numbers

Author

Le Gall, Alice, Rodriguez, S., Garcia, A., Radebaugh, J., Lorenz, R. D., Lopes, R. M. C., Hayes, A., Reflet, E., 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), Centre d'Etude de Saclay, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Geological Sciences [BYU], Brigham Young University (BYU), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Earth and Planetary Science [UC Berkeley] (EPS), University of California [Berkeley], University of California-University of California, University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

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

Thousands of dunes observed on the surface of Saturn's moon Titan were one of the greatest surprises uncovered by the Cassini spacecraft [1]. Dunes point to the mobility and processing of sediments on Titan - they are the telltale signatures of wind at work. As such, they provide crucial insights into the geology and climatic history of Titan. Being likely mainly composed of solid organics, they also hold clues on the methane and carbon cycles on Titan. In this paper, we will put numbers on dune areal coverage, volume, altitude and latitude distribution and show how these numbers can help understand past and present conditions on Titan.

Published
2012

35. Varied Geologic Terrains at Titan's South Pole: First Results from T39

Author

STOFAN, E. R., ELACHI, C., LUNINE, J.I., LORENZ, R. D., KIRK, R. L., LOPES, R. M. C., WOOD, C. A., RADEBAUGH, J., WALL, S. D., MITCHELL, K. L., SODERBLOM, L. A., PAILLOU, Philippe, FARR, T., STILES, B., CALLAHAN, P., CASSINI RADAR TEAM, Proxemy Research Inc, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, US Geological Survey [Flagstaff], United States Geological Survey [Reston] (USGS), Wheeling Jesuit University, 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), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), and Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

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; The Cassini RADAR pass T39 of the south polar region reveals extremely varied and in some cases complex surface morphologies, indicating that a range of geologic processes have operated, and are operating, in the region.

Published
2008

36. Degraded Impact Craters on Titan

Author

WOOD, C. A., LUNINE, J.I., STOFAN, E. R., LORENZ, R. D., LOPES, R. M. C., RADEBAUGH, J., WALL, S. D., PAILLOU, Philippe, FARR, T., Wheeling Jesuit University, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Proxemy Research Inc, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), 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), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), and Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

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], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2008

37. Titan's North Polar Lakes as Observed by Cassini Radar: An Update

Author

MITCHELL, K. L., WALL, S. D., STOFAN, E. R., LOPES, R. M. C., JANSSEN, M., STILES, B., PAILLOU, Philippe, MITRI, G., LUNINE, J., OSTRO, S., LORENZ, R. D., FARR, T. G., KIRK, R. L., RADEBAUGH, J., CASSINI RADAR SCIENCE TEAM, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Proxemy Research Inc, 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), Observatoire aquitain des sciences de l'univers (OASU), 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), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), US Geological Survey [Flagstaff], and United States Geological Survey [Reston] (USGS)

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], ComputingMilieux_MISCELLANEOUS
Abstract

International audience; Not Available

Published
2007

38. Surface albedo spectral properties of geologically interesting areas on Titan

Author

Solomonidou, A., primary, Hirtzig, M., additional, Coustenis, A., additional, Bratsolis, E., additional, Le Mouélic, S., additional, Rodriguez, S., additional, Stephan, K., additional, Drossart, P., additional, Sotin, C., additional, Jaumann, R., additional, Brown, R. H., additional, Kyriakopoulos, K., additional, Lopes, R. M. C., additional, Bampasidis, G., additional, Stamatelopoulou-Seymour, K., additional, and Moussas, X., additional

Published
2014
Full Text
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39. Cryovolcanism on Titan: New results from Cassini RADAR and VIMS

Author

Lopes, R. M. C., primary, Kirk, R. L., additional, Mitchell, K. L., additional, LeGall, A., additional, Barnes, J. W., additional, Hayes, A., additional, Kargel, J., additional, Wye, L., additional, Radebaugh, J., additional, Stofan, E. R., additional, Janssen, M. A., additional, Neish, C. D., additional, Wall, S. D., additional, Wood, C. A., additional, Lunine, J. I., additional, and Malaska, M. J., additional

Published
2013
Full Text
View/download PDF

41. Eruption of ammonia-water cryomagmas on Titan 2: eruption styles and landforms

Author

Mitchell, K. L., Lopes, R. M. C., Robshaw, Linda E., Kargel, J. S., Lunine, J., Lorenz, R., Petford, N., Stofan, E., Wilson, Lionel, Cassini Radar Science Team, The, Mitchell, K. L., Lopes, R. M. C., Robshaw, Linda E., Kargel, J. S., Lunine, J., Lorenz, R., Petford, N., Stofan, E., Wilson, Lionel, and Cassini Radar Science Team, The

Published
2006

42. Lava thicknesses: Implications for rheological and crustal development

Author

Kilburn, C. R. J and Lopes, R. M. C

Subjects
Geophysics
Abstract

The morphology of a lava flow is strongly influenced by its rheological structure. The rheological structure is, in turn, dependent on numerous factors including: (1) bulk composition, (2) crystallingity, (3) vesicularity, and (4) crustal development. Identifying which of the latter factors are most significant, and hence most readily investigated by remote-sensing techniques, is necessary to clarify short-term objectives and expectations from the study of Martian lava flows. Insights into the rheological controls on flow morphology are provided by variations in thickness of undrained lava streams on Etna and Vesuvius, Southern Italy. Both pahoehoe and aa lavas were studied.

Published
1988

43. Mars - Stratigraphy and gravimetry of Olympus Mons and its aureole

Author

Hiller, K. H, Neukum, G. P. O, Janle, P, Guest, J. E, and Lopes, R. M. C

Subjects
Lunar And Planetary Exploration
Abstract

The relative ages of the major geologic units on and around Olympus Mons are considered, together with an interpretation of the gravity anomaly found for this area. The crater data for this investigation have been acquired and interpreted according to the method outlined by Neukum and Hiller (1981). After careful geological mapping, craters clearly identified as impacts are measured and counted. Crater frequency values per sq km for craters greater than or equal to 1 km ('crater retention ages') are read from the individual counts by fitting the Martian cumulative crater production size-frequency distribution to the individual counts. In addition to age dating, the problem of the origin and nature of the aureole materials using gravity data is addressed. This is done by determining whether the line-of-sight gravity extending from Olympus Mons to the northwestern part of the aureole can be explained by the aureole masses alone or whether additional high-density intrusive masses must be assumed in the aureola area.

Published
1982

45. FIRST USGS GLOBAL GEOLOGIC MAP OF TITAN.

Author

Williams, D. A., Malaska, M. J., Lopes, R. M. C., Schoenfeld, A. M., and Birch, S. P. D.

Subjects
GEOLOGICAL maps, GEOLOGICAL mapping, SYNTHETIC aperture radar
Published
2021

46. A GLOBAL GEOLOGICAL MAP OF PLUTO AT 1:7M SCALE.

Author

White, O. L., Singer, K. N., Williams, D. A., Moore, J. M., and Lopes, R. M. C.

Subjects
PLUTO (Dwarf planet), GEOLOGICAL mapping, GEOLOGICAL maps, ICE prevention & control, ATMOSPHERIC circulation
Published
2021

49. THE GEOLOGY OF PLUTO.

Author

Singer, K. N., White, O. L., Moore, J. M., Howard, A. D., Schenk, P. M., Williams, D. A., Lopes, R. M. C., Stern, S. A., Ennico, K., Olkin, C. B., Weaver, H. A., and Young, L. A.

Subjects
PLUTO (Dwarf planet), GEOLOGY, PHYSIOGRAPHIC provinces, PLANETARY science, GLACIAL landforms
Published
2019

50. PROGRESS ON GLOBAL GEOLOGIC MAPPING OF PLUTO.

Author

White, O. L., Singer, K. N., Williams, D. A., Moore, J. M., Lopes, R. M. C., Stern, S. A., and McGovern, P. J.

Subjects
GEOLOGICAL maps, PLUTO (Dwarf planet), GEOLOGICAL mapping, GEOLOGICAL surveys
Abstract

We are using established planetary geologic mapping techniques [1] to produce a global US Geological Survey Scientific Investigations Map (SIM) at 1:7M scale for the >75% of Pluto's surface that was imaged during the New Horizons flyby in 2015. The well-resolved encounter hemisphere is covered by imaging between 76 to 890 m/pixel, and the poorly-resolved far side by imaging between 2.2 to 40.6 km/pixel. We have divided Pluto's encounter hemisphere into six geological groups, with each group consisting of units that are interpreted to represent a distinct episode of geological activity on Pluto's surface (Fig. 1). We will present a summary of the mapping that has been completed to date, which includes the Sputnik, Wright, Tartarus, and Hayabusa groups, in addition to structural mapping of the entire encounter hemisphere [2]. Geologic mapping of Pluto's far side has been completed for a separate study [3], the line work of which will be imported into the final SIM upon completion of mapping of the encounter hemisphere. [ABSTRACT FROM AUTHOR]

Published
2021

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