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Cravens TE, Richard M, Ma YJ, Bertucci C, Luhmann JG, Ledvina S, Robertson IP, Wahlund JE, Ågren K, Cui J, Muller-Wodarg I, Waite JH, Dougherty M, Bell J, Ulusen D. Dynamical and magnetic field time constants for Titan's ionosphere: Empirical estimates and comparisons with Venus. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009ja015050] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- T. E. Cravens
- Department of Physics and Astronomy; University of Kansas; Lawrence Kansas USA
| | - M. Richard
- Department of Physics and Astronomy; University of Kansas; Lawrence Kansas USA
| | - Y.-J. Ma
- Institute of Geophysics and Planetary Physics; University of California; Los Angeles California USA
| | - C. Bertucci
- Instituto de Astronomía y Física del Espacio; Buenos Aires Argentina
| | - J. G. Luhmann
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - S. Ledvina
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - I. P. Robertson
- Department of Physics and Astronomy; University of Kansas; Lawrence Kansas USA
| | | | - K. Ågren
- Swedish Institute of Space Physics; Uppsala Sweden
| | - J. Cui
- Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
| | - I. Muller-Wodarg
- Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
| | - J. H. Waite
- Southwest Research Institute; San Antonio Texas USA
| | - M. Dougherty
- Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
| | - J. Bell
- Southwest Research Institute; San Antonio Texas USA
| | - D. Ulusen
- Space Sciences Laboratory; University of California; Berkeley California USA
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Winglee RM, Snowden D, Kidder A. Modification of Titan's ion tail and the Kronian magnetosphere: Coupled magnetospheric simulations. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008ja013343] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- R. M. Winglee
- Department of Earth and Space Science; University of Washington; Seattle Washington USA
| | - D. Snowden
- Department of Earth and Space Science; University of Washington; Seattle Washington USA
| | - A. Kidder
- Department of Earth and Space Science; University of Washington; Seattle Washington USA
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3
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Johnson RE. Sputtering and heating of Titan's upper atmosphere. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:753-771. [PMID: 19073463 DOI: 10.1098/rsta.2008.0244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Titan is an important endpoint for understanding atmospheric evolution. Prior to Cassini's arrival at Saturn, modelling based on Voyager data indicated that the hydrogen escape rate was large (1-3x1028amus-1), but the escape rates for carbon and nitrogen species were relatively small (5x1026amus-1) and dominated by atmospheric sputtering. Recent analysis of the structure of Titan's thermosphere and corona attained from the Ion and Neutral Mass Spectrometer and the Huygens Atmospheric Structure Instrument on Cassini have led to substantially larger estimates of the loss rate for heavy species (0.3-5x1028amus-1). At the largest rate suggested, a mass that is a significant fraction of the present atmosphere would have been lost to space in 4Gyr; hence, understanding the nature of the processes driving escape is critical. The recent estimates of neutral escape are reviewed here, with particular emphasis on plasma-induced sputtering and heating. Whereas the loss of hydrogen is clearly indicated by the altitude dependence of the H2 density, three different one-dimensional models were used to estimate the heavy-molecule loss rate using the Cassini data for atmospheric density versus altitude. The solar heating rate and the nitrogen density profile versus altitude were used in a fluid dynamic model to extract an average net upward flux below the exobase; the diffusion of methane through nitrogen was described below the exobase using a model that allowed for outward flow; and the coronal structure above the exobase was simulated by presuming that the observed atmospheric structure was due to solar- and plasma-induced hot particle production. In the latter, it was hypothesized that hot recoils from photochemistry or plasma-ion-induced heating were required. In the other two models, the upward flow extracted is driven by heat conduction from below, which is assumed to continue to act above the nominal exobase, producing a process referred to as 'slow hydrodynamic' escape. These models and the resulting loss rates are reviewed and compared. It is pointed out that preliminary estimates of the composition of the magnetospheric plasma at Titan's orbit appear to be inconsistent with the largest loss rates suggested for the heavy species, and the mean upward flow extracted in the one-dimensional models could be consistent with atmospheric loss by other mechanisms or with transport to other regions of Titan's atmosphere.
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Affiliation(s)
- Robert E Johnson
- University of Virginia, Charlottesville, VA 22904, USA Department of Physics, New York University, New York, NY 10003, USA.
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4
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Dandouras I, Garnier P, Mitchell DG, Roelof EC, Brandt PC, Krupp N, Krimigis SM. Titan's exosphere and its interaction with Saturn's magnetosphere. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:743-752. [PMID: 19073465 DOI: 10.1098/rsta.2008.0249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Titan's nitrogen-rich atmosphere is directly bombarded by energetic ions, due to its lack of a significant intrinsic magnetic field. Singly charged energetic ions from Saturn's magnetosphere undergo charge-exchange collisions with neutral atoms in Titan's upper atmosphere, or exosphere, being transformed into energetic neutral atoms (ENAs). The ion and neutral camera, one of the three sensors that comprise the magnetosphere imaging instrument (MIMI) on the Cassini/Huygens mission to Saturn and Titan, images these ENAs like photons, and measures their fluxes and energies. These remote-sensing measurements, combined with the in situ measurements performed in the upper thermosphere and in the exosphere by the ion and neutral mass spectrometer instrument, provide a powerful diagnostic of Titan's exosphere and its interaction with the Kronian magnetosphere. These observations are analysed and some of the exospheric features they reveal are modelled.
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Affiliation(s)
- Iannis Dandouras
- Centre d'Etude Spatiale des Rayonnements, Université de Toulouse, 31028 Toulouse, France CNRS, UMR 5187, 31028 Toulouse, France.
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Garnier P, Dandouras I, Toublanc D, Roelof EC, Brandt PC, Mitchell DG, Krimigis SM, Krupp N, Hamilton DC, Dutuit O, Wahlund JE. The lower exosphere of Titan: Energetic neutral atoms absorption and imaging. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008ja013029] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- P. Garnier
- Centre d'Etude Spatiale des Rayonnements; CNRS/Paul Sabatier University; Toulouse France
- Swedish Institute of Space Physics; Uppsala Sweden
| | - I. Dandouras
- Centre d'Etude Spatiale des Rayonnements; CNRS/Paul Sabatier University; Toulouse France
| | - D. Toublanc
- Centre d'Etude Spatiale des Rayonnements; CNRS/Paul Sabatier University; Toulouse France
| | - E. C. Roelof
- Applied Physics Laboratory; Johns Hopkins University; Laurel Maryland USA
| | - P. C. Brandt
- Applied Physics Laboratory; Johns Hopkins University; Laurel Maryland USA
| | - D. G. Mitchell
- Applied Physics Laboratory; Johns Hopkins University; Laurel Maryland USA
| | - S. M. Krimigis
- Applied Physics Laboratory; Johns Hopkins University; Laurel Maryland USA
| | - N. Krupp
- Max-Planck-Institut fur Sonnensystemforschung; Lindau Germany
| | - D. C. Hamilton
- Department of Physics; University of Maryland; College Park Maryland USA
| | - O. Dutuit
- Laboratoire de Planetologie de Grenoble; Universite Joseph Fourier; Grenoble France
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6
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Modolo R, Chanteur GM. A global hybrid model for Titan's interaction with the Kronian plasma: Application to the Cassini Ta flyby. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007ja012453] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- R. Modolo
- Centre d'Etudes des Environnements Terrestre et Plantaires; Institut Pierre Simon Laplace; Vélizy France
- Swedish Institute of Space Physics; Uppsala Sweden
| | - G. M. Chanteur
- Centre d'Etudes des Environnements Terrestre et Plantaires; Institut Pierre Simon Laplace; Vélizy France
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7
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Snowden D, Winglee R, Bertucci C, Dougherty M. Three-dimensional multifluid simulation of the plasma interaction at Titan. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2007ja012393] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- D. Snowden
- Department of Earth and Space Sciences; University of Washington; Seattle Washington USA
| | - R. Winglee
- Department of Earth and Space Sciences; University of Washington; Seattle Washington USA
| | - C. Bertucci
- Space and Atmospheric Physics Group; Imperial College London UK
| | - M. Dougherty
- Space and Atmospheric Physics Group; Imperial College London UK
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Sillanpää I, Kallio E, Jarvinen R, Janhunen P. Oxygen ions at Titan's exobase in a Voyager 1-type interaction from a hybrid simulation. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2007ja012348] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- I. Sillanpää
- Finnish Meteorological Institute; Helsinki Finland
| | - E. Kallio
- Finnish Meteorological Institute; Helsinki Finland
| | - R. Jarvinen
- Finnish Meteorological Institute; Helsinki Finland
| | - P. Janhunen
- Finnish Meteorological Institute; Helsinki Finland
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9
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De La Haye V, Waite JH, Johnson RE, Yelle RV, Cravens TE, Luhmann JG, Kasprzak WT, Gell DA, Magee B, Leblanc F, Michael M, Jurac S, Robertson IP. Cassini Ion and Neutral Mass Spectrometer data in Titan's upper atmosphere and exosphere: Observation of a suprathermal corona. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006ja012222] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - J. H. Waite
- Southwest Research Institute; San Antonio Texas USA
| | - R. E. Johnson
- Astronomy Department; University of Virginia; Charlottesville Virginia USA
| | - R. V. Yelle
- Lunar and Planetary Laboratory; University of Arizona; Tucson Arizona USA
| | - T. E. Cravens
- Department of Physics and Astronomy; University of Kansas; Lawrence Kansas USA
| | - J. G. Luhmann
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - W. T. Kasprzak
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - D. A. Gell
- Southwest Research Institute; San Antonio Texas USA
| | - B. Magee
- Southwest Research Institute; San Antonio Texas USA
| | - F. Leblanc
- Service d'Aéronomie du CNRS/IPSL; Paris France
| | - M. Michael
- Civil Engineering; Indian Institute of Technology; Kanpur India
| | - S. Jurac
- Center for Space Research; Massachusetts Institute of Technology; Cambridge Massachusetts USA
| | - I. P. Robertson
- Department of Physics and Astronomy; University of Kansas; Lawrence Kansas USA
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Dóbé Z, Szego K, Quest KB, Shapiro VD, Hartle RE, Sittler EC. Nonlinear evolution of modified two-stream instability above ionosphere of Titan: Comparison with the data of the Cassini Plasma Spectrometer. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006ja011770] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Zoltán Dóbé
- Központi Fizikai Kutató Intézet Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - Karoly Szego
- Központi Fizikai Kutató Intézet Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - Kevin B. Quest
- Electrical and Computer Engineering Department; University of California San Diego; La Jolla California USA
| | - Vitali D. Shapiro
- Electrical and Computer Engineering Department; University of California San Diego; La Jolla California USA
| | - R. E. Hartle
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - E. C. Sittler
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
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Sittler EC, Johnson RE, Smith HT, Richardson JD, Jurac S, Moore M, Cooper JF, Mauk BH, Michael M, Paranicas C, Armstrong TP, Tsurutani B. Energetic nitrogen ions within the inner magnetosphere of Saturn. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2004ja010509] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Ma Y, Nagy AF, Cravens TE, Sokolov IV, Hansen KC, Wahlund JE, Crary FJ, Coates AJ, Dougherty MK. Comparisons between MHD model calculations and observations of Cassini flybys of Titan. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005ja011481] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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Sittler EC, Hartle RE, Viñas AF, Johnson RE, Smith HT, Mueller-Wodarg I. Titan interaction with Saturn's magnetosphere: Voyager 1 results revisited. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004ja010759] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- E. C. Sittler
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - R. E. Hartle
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - A. F. Viñas
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - R. E. Johnson
- Department of Engineering Physics; University of Virginia; Charlottesville Virginia USA
| | - H. T. Smith
- Department of Engineering Physics; University of Virginia; Charlottesville Virginia USA
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Backes H, Neubauer FM, Dougherty MK, Achilleos N, André N, Arridge CS, Bertucci C, Jones GH, Khurana KK, Russell CT, Wennmacher A. Titan's Magnetic Field Signature During the First Cassini Encounter. Science 2005; 308:992-5. [PMID: 15890875 DOI: 10.1126/science.1109763] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The magnetic field signature obtained by Cassini during its first close encounter with Titan on 26 October 2004 is presented and explained in terms of an advanced model. Titan was inside the saturnian magnetosphere. A magnetic field minimum before closest approach marked Cassini's entry into the magnetic ionopause layer. Cassini then left the northern and entered the southern magnetic tail lobe. The magnetic field before and after the encounter was approximately constant for approximately 20 Titan radii, but the field orientation changed exactly at the location of Titan's orbit. No evidence of an internal magnetic field at Titan was detected.
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Affiliation(s)
- Heiko Backes
- Institut für Geophysik und Meteorologie, Universität zu Köln, Albertus Magnus Platz, 50678 Cologne, Germany.
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Luna H. Dissociation of N2in capture and ionization collisions with fast H+and N+ions and modeling of positive ion formation in the Titan atmosphere. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002je001950] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Nagy AF, Liu Y, Hansen KC, Kabin K, Gombosi TI, Combi MR, DeZeeuw DL, Powell KG, Kliore AJ. The interaction between the magnetosphere of Saturn and Titan's ionosphere. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja000183] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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