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1. Pioneer Venus Orbiter Observations of Solar Wind Driven Magnetosonic Waves Interacting With the Dayside Venusian Ionosphere

Author

Fowler, C. M., Ledvina, S., Chaston, C. C., Persson, Moa, Ramstad, R., Luhmann, J., Fowler, C. M., Ledvina, S., Chaston, C. C., Persson, Moa, Ramstad, R., and Luhmann, J.

Abstract

We use in situ plasma observations made by the Pioneer Venus Orbiter spacecraft to show for the first time that magnetosonic waves can couple the solar wind to the upper ionosphere and deposit energy there. The waves are generated upstream of Venus, are advected into the shock and propagate across the draped magnetic field, through the magnetosheath and into the dayside upper ionosphere. The magnetosonic waves damp in the upper ionosphere in a region where physical collisions are rare, and electromagnetic forces must control this damping. The waves damp when the ionospheric heavy ion density is a few thousand cm-3 and wave-particle interactions with the dominant O+ ions are postulated as the damping mechanism. Estimates of ion heating rates show that 1%-5% of the O+ ion distribution function could be heated to escape energy in 10-40 s.

Published
2024
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2. Chemical interactions between Saturn’s atmosphere and its rings

Author

Waite, J. H., Perryman, R. S., Perry, M. E., Miller, K. E., Belll, J., Cravens, T. E., Glein, C. R., Grimes, J., Hedman, M., Cuzzi, J., Brockwell, T., Teolis, B., Moore, L., Mitchell, D. G., Persoon, A., Kurth, W. S., Wahlund, J.-E., Morooka, M., Hadid, L. Z., S. Chocron, J. Walker, Nagy, A., Yelle, R., Ledvina, S., Johnson, R., Tseng, W., Tucker, O. J., and Ip, W.-H.

Published
2018

5. Oxygen Ions Observed near Saturn's A Ring

Author

Waite, J. H., Cravens, T. E., Kasprzak, W. T., Luhmann, J. G., McNutt, R. L., Niemann, H. B., Yelle, R. V., Mueller-Wodarg, I., Ledvina, S. A., and Scherer, S.

Published
2005

7. Plasma Flow and Related Phenomena in Planetary Aeronomy

Author

Ma, Y.-J., Altwegg, K., Breus, T., Combi, M. R., Cravens, T. E., Kallio, E., Ledvina, S. A., Luhmann, J. G., Miller, S., Nagy, A. F., Ridley, A. J., Strobel, D. F., Nagy, Andrew F., editor, Balogh, André, editor, Cravens, Thomas E., editor, Mendillo, Michael, editor, and Mueller-Wodarg, Ingo, editor

Published
2008
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9. A Review of General Physical and Chemical Processes Related to Plasma Sources and Losses for Solar System Magnetospheres

Author

Seki, K., primary, Nagy, A., additional, Jackman, C. M., additional, Crary, F., additional, Fontaine, D., additional, Zarka, P., additional, Wurz, P., additional, Milillo, A., additional, Slavin, J. A., additional, Delcourt, D. C., additional, Wiltberger, M., additional, Ilie, R., additional, Jia, X., additional, Ledvina, S. A., additional, Liemohn, M. W., additional, and Schunk, R. W., additional

Published
2016
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10. Investigation of the force balance in the Titan ionosphere: Cassini T5 flyby model/data comparisons

Author

Ulusen, D., Luhmann, J.G., Ma, Y.-J., Ledvina, S., Cravens, T.E., Mandt, K., Waite, J.H., and Wahlund, J.-E.

Subjects
Radiation -- Analysis, Magnetic fields -- Analysis, Geophysics -- Analysis, Atmosphere -- Analysis, Earth -- Atmosphere, Earth -- Analysis, Astronomy, Earth sciences
Abstract

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.07.004 Byline: D. Ulusen (a), J.G. Luhmann (a), Y.-J. Ma (b), S. Ledvina (a), T.E. Cravens (c), K. Mandt (d), J.H. Waite (d), J.-E. Wahlund (e) Keywords: Titan; Saturn, Satellites; Ionospheres Abstract: Cassini's Titan flyby on 16 April, 2005 (T5) is the only encounter when the two main ionizing sources of the moon's atmosphere, solar radiation and corotating plasma, align almost anti-parallel. In this paper a single-fluid multi-species 3D MHD model of the magnetospheric plasma interaction for T5 conditions is analyzed. Model results are compared to observations to investigate the ionospheric dynamics at Titan as well as to understand the deviations from a typical solar wind interaction, such as Venus' interaction with the solar wind. Model results suggest that for the T5 interaction configuration, corotating plasma is the dominant driver determining the global interaction features at high altitudes. In the lower ionosphere below [approximately equal to]1500km altitude - where the control of the ionospheric composition transfers from dynamic to chemical processes - magnetic and thermal pressure gradients oppose each other locally, complicating the ionospheric dynamics. Model results also imply that the nightside ionosphere - produced only by the impact ionization in the model - does not provide enough thermal pressure to balance the incident plasma dynamic pressure. As a result, the induced magnetic barrier penetrates into the ionosphere by plasma convection down to [approximately equal to]1000km altitude and by magnetic diffusion below this altitude. Moreover, strong horizontal drag forces due to ion-neutral collisions and comparable drag forces estimated from possible neutral winds in the lower ionosphere below [approximately equal to]1400km altitude oppose over local regions, implying that the Titan interaction must be treated as a 3D problem. Ion and electron densities calculated from the model generally agree with the Cassini Ion Neutral Mass Spectrometer and Langmuir probe measurements; however, there are significant differences between the calculated and measured magnetic fields. We discuss possible explanations for the discrepancy in the magnetic field predictions. Author Affiliation: (a) Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA (b) Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90025, USA (c) Dept. of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA (d) Southwest Research Institute, 6220 Culebra Rd., P.O. Drawer 28510, San Antonio, TX 78284, USA (e) Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden Article History: Received 5 April 2010; Revised 19 June 2010; Accepted 5 July 2010

Published
2010

11. TandEM: Titan and Enceladus mission

Author

Coustenis, A., Atreya, S. K., Balint, T., Brown, R. H., Dougherty, M. K., Ferri, F., Fulchignoni, M., Gautier, D., Gowen, R. A., Griffith, C. A., Gurvits, L. I., Jaumann, R., Langevin, Y., Leese, M. R., Lunine, J. I., McKay, C. P., Moussas, X., Müller-Wodarg, I., Neubauer, F., Owen, T. C., Raulin, F., Sittler, E. C., Sohl, F., Sotin, C., Tobie, G., Tokano, T., Turtle, E. P., Wahlund, J.-E., Waite, J. H., Baines, K. H., Blamont, J., Coates, A. J., Dandouras, I., Krimigis, T., Lellouch, E., Lorenz, R. D., Morse, A., Porco, C. C., Hirtzig, M., Saur, J., Spilker, T., Zarnecki, J. C., Choi, E., Achilleos, N., Amils, R., Annan, P., Atkinson, D. H., Bénilan, Y., Bertucci, C., Bézard, B., Bjoraker, G. L., Blanc, M., Boireau, L., Bouman, J., Cabane, M., Capria, M. T., Chassefière, E., Coll, P., Combes, M., Cooper, J. F., Coradini, A., Crary, F., Cravens, T., Daglis, I. A., de Angelis, E., de Bergh, C., de Pater, I., Dunford, C., Durry, G., Dutuit, O., Fairbrother, D., Flasar, F. M., Fortes, A. D., Frampton, R., Fujimoto, M., Galand, M., Grasset, O., Grott, M., Haltigin, T., Herique, A., Hersant, F., Hussmann, H., Ip, W., Johnson, R., Kallio, E., Kempf, S., Knapmeyer, M., Kofman, W., Koop, R., Kostiuk, T., Krupp, N., Küppers, M., Lammer, H., Lara, L.-M., Lavvas, P., Le Mouélic, S., Lebonnois, S., Ledvina, S., Li, J., Livengood, T. A., Lopes, R. M., Lopez-Moreno, J.-J., Luz, D., Mahaffy, P. R., Mall, U., Martinez-Frias, J., Marty, B., McCord, T., Menor Salvan, C., Milillo, A., Mitchell, D. G., Modolo, R., Mousis, O., Nakamura, M., Neish, C. D., Nixon, C. A., Nna Mvondo, D., Orton, G., Paetzold, M., Pitman, J., Pogrebenko, S., Pollard, W., Prieto-Ballesteros, O., Rannou, P., Reh, K., Richter, L., Robb, F. T., Rodrigo, R., Rodriguez, S., Romani, P., Ruiz Bermejo, M., Sarris, E. T., Schenk, P., Schmitt, B., Schmitz, N., Schulze-Makuch, D., Schwingenschuh, K., Selig, A., Sicardy, B., Soderblom, L., Spilker, L. J., Stam, D., Steele, A., Stephan, K., Strobel, D. F., Szego, K., Szopa, C., Thissen, R., Tomasko, M. G., Toublanc, D., Vali, H., Vardavas, I., Vuitton, V., West, R. A., Yelle, R., and Young, E. F.

Published
2009
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13. Titan Ion Composition at Magnetosphere-Ionosphere Transition Region

Author

Sittler, Edward C, Hartle, R. E, Shappirio, M, Simpson, D. J, COoper, J. F, Burger, M. H, Johnson, R. E, Bertucci, C, Luhman, J. G, Ledvina, S. A, Szego, K, Coates, A. J, and Young, D. T

Subjects
Lunar And Planetary Science And Exploration
Abstract

Using Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS) ion composition data, we will investigate the compositional changes at the transition region between Saturn's magnetospheric flow and Titan's upper ionosphere. It is this region where scavenging of Titan's upper ionosphere can occur, where it is then dragged away by the magnetospheric flow as cold plasma for Saturn's magnetosphere. This cold plasma may form plumes as originally proposed by (1) during the Voyager 1 epoch. This source of cold plasma may have a unique compositional signature such as methane group ions. Water group ions that are observed in Saturn's outer magnetosphere (2,3) are relatively hot and probably come from the inner magnetosphere where they are born from fast neutrals escaping Enceladus (4) and picked up in the outer magnetosphere as hot plasma (5). This scenario will be complicated by pickup methane ions within Titan's mass loading region, as originally predicted by (6) based on Voyager 1 data and observationally confirmed by (3,7) using CAPS IMS data. But, CH4(+) ions or their fragments can only be produced as pickup ions from Titan's exosphere which can extend beyond the transition region of concern here, while CH5(+) ions can be scavenged from Titan's ionosphere. We will investigate these possibilities.

Published
2006

14. Chemical interactions between Saturn's atmosphere and its rings

Author

Waite, J. H., Jr., Perryman, R. S., Perry, M. E., Miller, K. E., Bell, J., Cravens, T. E., Glein, C. R., Grimes, J., Hedman, M., Cuzzi, J., Brockwell, T., Teolis, B., Moore, L., Mitchell, D. G., Persoon, A., Kurth, W. S., Wahlund, Jan-Erik, Morooka, Michiko, Hadid, Lina Z, Chocron, S., Walker, J., Nagy, A., Yelle, R., Ledvina, S., Johnson, R., Tseng, W., Tucker, O. J., Ip, W. -H, Waite, J. H., Jr., Perryman, R. S., Perry, M. E., Miller, K. E., Bell, J., Cravens, T. E., Glein, C. R., Grimes, J., Hedman, M., Cuzzi, J., Brockwell, T., Teolis, B., Moore, L., Mitchell, D. G., Persoon, A., Kurth, W. S., Wahlund, Jan-Erik, Morooka, Michiko, Hadid, Lina Z, Chocron, S., Walker, J., Nagy, A., Yelle, R., Ledvina, S., Johnson, R., Tseng, W., Tucker, O. J., and Ip, W. -H

Abstract

The Pioneer and Voyager spacecraft made close-up measurements of Saturn's ionosphere and upper atmosphere in the 1970s and 1980s that suggested a chemical interaction between the rings and atmosphere. Exploring this interaction provides information on ring composition and the influence on Saturn's atmosphere from infalling material. The Cassini Ion Neutral Mass Spectrometer sampled in situ the region between the D ring and Saturn during the spacecraft's Grand Finale phase. We used these measurements to characterize the atmospheric structure and material influx from the rings. The atmospheric He/H-2 ratio is 10 to 16%. Volatile compounds from the rings (methane; carbon monoxide and/or molecular nitrogen), as well as larger organic-bearing grains, are flowing inward at a rate of 4800 to 45,000 kilograms per second.

Published
2018
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16. Dynamical and magnetic field time constants for Titan's ionosphere: Empirical estimates and comparisons with Venus

Author

Cravens, T. E., Richard, M., Ma, Y. J., Bertucci, Cesar, Luhmann, J. G., Ledvina, S., Robertson, I. P., Wahlund, J. E., Ågren, K., Cui, J., Muller Wodarg, I., Waite, J. H., Dougherty, M., Bell, J., and Ulusen, D.

Subjects
purl.org/becyt/ford/1 [https], Ionosphere/magnetosphere interactions [Ionosphere], Astronomía, Ciencias Físicas, Ionosphere/atmosphere interactions [Ionosphere], purl.org/becyt/ford/1.3 [https], Ionospheric dynamics [Ionosphere], CIENCIAS NATURALES Y EXACTAS, Comets and Small Bodies: Ionospheres (2459), Planetary Sciences: Solar System Objects: Titan [Planetary Sciences]
Abstract

Plasma in Titan´s ionosphere flows in response to forcing from thermal pressure gradients, magnetic forces, gravity, and ion-neutral collisions. This paper takes an empirical approach to the ionospheric dynamics by using data from Cassini instruments to estimate pressures, flow speeds, and time constants on the dayside and nightside. The plasma flow speed relative to the neutral gas speed is approximately 1 m s‑1 near an altitude of 1000 km and 200 m s‑1 at 1500 km. For comparison, the thermospheric neutral wind speed is about 100 m s‑1. The ionospheric plasma is strongly coupled to the neutrals below an altitude of about 1300 km. Transport, vertical or horizontal, becomes more important than chemistry in controlling ionospheric densities above about 1200-1500 km, depending on the ion species. Empirical estimates are used to demonstrate that the structure of the ionospheric magnetic field is determined by plasma transport (including neutral wind effects) for altitudes above about 1000 km and by magnetic diffusion at lower altitudes. The paper suggests that a velocity shear layer near 1300 km could exist at some locations and could affect the structure of the magnetic field. Both Hall and polarization electric field terms in the magnetic induction equation are shown to be locally important in controlling the structure of Titan´s ionospheric magnetic field. Comparisons are made between the ionospheric dynamics at Titan and at Venus. Fil: Cravens, T. E.. University of Kansas; Estados Unidos Fil: Richard, M.. University of Kansas; Estados Unidos Fil: Ma, Y. J.. University of California; Estados Unidos Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Luhmann, J. G.. University of California; Estados Unidos Fil: Ledvina, S.. University of California; Estados Unidos Fil: Robertson, I. P.. University of Kansas; Estados Unidos Fil: Wahlund, J. E.. Swedish Institute of Space Physics; Suecia Fil: Ågren, K.. Swedish Institute of Space Physics; Suecia Fil: Cui, J.. Imperial College London; Reino Unido Fil: Muller Wodarg, I.. Imperial College London; Reino Unido Fil: Waite, J. H.. Southwest Research Institute; Estados Unidos Fil: Dougherty, M.. Imperial College London; Reino Unido Fil: Bell, J.. Southwest Research Institute; Estados Unidos Fil: Ulusen, D.. University of California; Estados Unidos

Published
2010

17. TandEM: Titan and Enceladus mission

Author

Coustenis, A. Atreya, S.K. Balint, T. Brown, R.H. Dougherty, M.K. Ferri, F. Fulchignoni, M. Gautier, D. Gowen, R.A. Griffith, C.A. Gurvits, L.I. Jaumann, R. Langevin, Y. Leese, M.R. Lunine, J.I. McKay, C.P. Moussas, X. Müller-Wodarg, I. Neubauer, F. Owen, T.C. Raulin, F. Sittler, E.C. Sohl, F. Sotin, C. Tobie, G. Tokano, T. Turtle, E.P. Wahlund, J.-E. Waite, J.H. Baines, K.H. Blamont, J. Coates, A.J. Dandouras, I. Krimigis, T. Lellouch, E. Lorenz, R.D. Morse, A. Porco, C.C. Hirtzig, M. Saur, J. Spilker, T. Zarnecki, J.C. Choi, E. Achilleos, N. Amils, R. Annan, P. Atkinson, D.H. Bénilan, Y. Bertucci, C. Bézard, B. Bjoraker, G.L. Blanc, M. Boireau, L. Bouman, J. Cabane, M. Capria, M.T. Chassefière, E. Coll, P. Combes, M. Cooper, J.F. Coradini, A. Crary, F. Cravens, T. Daglis, I.A. de Angelis, E. de Bergh, C. de Pater, I. Dunford, C. Durry, G. Dutuit, O. Fairbrother, D. Flasar, F.M. Fortes, A.D. Frampton, R. Fujimoto, M. Galand, M. Grasset, O. Grott, M. Haltigin, T. Herique, A. Hersant, F. Hussmann, H. Ip, W. Johnson, R. Kallio, E. Kempf, S. Knapmeyer, M. Kofman, W. Koop, R. Kostiuk, T. Krupp, N. Küppers, M. Lammer, H. Lara, L.-M. Lavvas, P. Le Mouélic, S. Lebonnois, S. Ledvina, S. Li, J. Livengood, T.A. Lopes, R.M. Lopez-Moreno, J.-J. Luz, D. Mahaffy, P.R. Mall, U. Martinez-Frias, J. Marty, B. McCord, T. Salvan, C.M. Milillo, A. Mitchell, D.G. Modolo, R. Mousis, O. Nakamura, M. Neish, C.D. Nixon, C.A. Mvondo, D.N. Orton, G. Paetzold, M. Pitman, J. Pogrebenko, S. Pollard, W. Prieto-Ballesteros, O. Rannou, P. Reh, K. Richter, L. Robb, F.T. Rodrigo, R. Rodriguez, S. Romani, P. Bermejo, M.R. Sarris, E.T. Schenk, P. Schmitt, B. Schmitz, N. Schulze-Makuch, D. Schwingenschuh, K. Selig, A. Sicardy, B. Soderblom, L. Spilker, L.J. Stam, D. Steele, A. Stephan, K. Strobel, D.F. Szego, K. Szopa, C. Thissen, R. Tomasko, M.G. Toublanc, D. Vali, H. Vardavas, I. Vuitton, V. West, R.A. Yelle, R. Young, E.F.

Abstract

TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfière) and possibly several landing probes to be delivered through the atmosphere. © Springer Science + Business Media B.V. 2008.

Published
2009

18. An Analysis of the Solar Wind Control of the SKR Rotation Period

Author

Lee, Christina, Luhmann, J. G., Odstrcil, Dusan, Macneice, P., Arge, C. N., Kurth, William S., Ledvina, S. A., Lecacheux, Alain, de Pater, Imke, 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), Physique des plasmas, and 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)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2006

20. Plasma Flow and Related Phenomena in Planetary Aeronomy

Author

Ma, Y.-J., primary, Altwegg, K., additional, Breus, T., additional, Combi, M. R., additional, Cravens, T. E., additional, Kallio, E., additional, Ledvina, S. A., additional, Luhmann, J. G., additional, Miller, S., additional, Nagy, A. F., additional, Ridley, A. J., additional, and Strobel, D. F., additional

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22. Investigating magnetospheric interaction effects on Titan's ionosphere with the Cassini orbiter Ion Neutral Mass Spectrometer, Langmuir Probe and magnetometer observations during targeted flybys

Author

Luhmann, J. G., Ulusen, D., Ledvina, S. A., Mandt, K., Magee, B., Waite, J. H., Westlake, J., Cravens, T. E., Robertson, I., Edberg, Niklas, Ågren, Karin, Wahlund, Jan-Erik, Ma, Y. -J, Wei, H., Russell, C. T., Dougherty, M. K., Luhmann, J. G., Ulusen, D., Ledvina, S. A., Mandt, K., Magee, B., Waite, J. H., Westlake, J., Cravens, T. E., Robertson, I., Edberg, Niklas, Ågren, Karin, Wahlund, Jan-Erik, Ma, Y. -J, Wei, H., Russell, C. T., and Dougherty, M. K.

Abstract

In the similar to 6 years since the Cassini spacecraft went into orbit around Saturn in 2004, roughly a dozen Titan flybys have occurred for which the Ion Neutral Mass Spectrometer (INMS) measured that moon's ionospheric density and composition. For these, and for the majority of the similar to 60 close flybys probing to altitudes down to similar to 950 km, Langmuir Probe electron densities were also obtained. These were all complemented by Cassini magnetometer observations of the magnetic fields affected by the Titan plasma interaction. Titan's ionosphere was expected to differ from those of other unmagnetized planetary bodies because of significant contributions from particle impact due to its magnetospheric environment. However, previous analyses of these data clearly showed the dominance of the solar photon source, with the possible exception of the nightside. This paper describes the collected ionospheric data obtained in the period between Cassini's Saturn Orbit Insertion in 2004 and 2009, and examines some of their basic characteristics with the goal of searching for magnetospheric influences. These influences might include effects on the altitude profiles of impact ionization by magnetospheric particles at the Titan orbit location, or by locally produced pickup ions freshly created in Titan's upper atmosphere. The effects of forces on the ionosphere associated with both the draped and penetrating external magnetic fields might also be discernable. A number of challenges arise in such investigations given both the observed order of magnitude variations in the magnetospheric particle sources and the unsteadiness of the magnetospheric magnetic field and plasma flows at Titan's (similar to 20Rs (Saturn Radius)) orbit. Transterminator flow of ionospheric plasma from the dayside may also supply some of the nightside ionosphere, complicating determination of the magnetospheric contribution. Moreover, we are limited by the sparse sampling of the ionosphere during th

Published
2012
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23. A comparison of global models for the solar wind interaction with Mars

Author

Brain, D., Barabash, S., Boesswetter, A., Bougher, S., Brecht, S., Chanteur, G., Hurley, D., Dubinin, E., Fang, X., Fraenz, M., Halekas, J., Harnett, E., Holmström, M., Kallio, E., Lammer, H., Ledvina, S., Liemohn, M., Liu, K., Luhmann, J., Ma, Y., Modolo, Ronan, Nagy, A., Motschmann, U., Nilsson, H., Shinagawa, H., Simon, S., Terada, N., Brain, D., Barabash, S., Boesswetter, A., Bougher, S., Brecht, S., Chanteur, G., Hurley, D., Dubinin, E., Fang, X., Fraenz, M., Halekas, J., Harnett, E., Holmström, M., Kallio, E., Lammer, H., Ledvina, S., Liemohn, M., Liu, K., Luhmann, J., Ma, Y., Modolo, Ronan, Nagy, A., Motschmann, U., Nilsson, H., Shinagawa, H., Simon, S., and Terada, N.

Abstract

We present initial results from the first community-wide effort to compare global plasma interaction model results for Mars. Seven modeling groups participated in this activity, using MHD, multi-fluid, and hybrid assumptions in their simulations. Moderate solar wind and solar EUV conditions were chosen, and the conditions were implemented in the models and run to steady state. Model output was compared in three ways to determine how pressure was partitioned and conserved in each model, the location and asymmetry of plasma boundaries and pathways for planetary ion escape, and the total escape flux of planetary oxygen ions. The two participating MHD models provided similar results, while the five sets of multi-fluid and hybrid results were different in many ways. All hybrid results, however, showed two main channels for oxygen ion escape (a pickup ion 'plume' in the hemisphere toward which the solar wind convection electric field is directed, and a channel in the opposite hemisphere of the central magnetotail), while the MHD models showed one (a roughly symmetric channel in the central magnetotail). Most models showed a transition from an upstream region dominated by plasma dynamic pressure to a magnetosheath region dominated by thermal pressure to a low altitude region dominated by magnetic pressure. However, calculated escape rates for a single ion species varied by roughly an order of magnitude for similar input conditions, suggesting that the uncertainties in both the current and integrated escape over martian history as determined by models are large. These uncertainties are in addition to those associated with the evolution of the Sun, the martian dynamo, and the early atmosphere, highlighting the challenges we face in constructing Mars' past using models.

Published
2010
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24. Dynamical and magnetic field time constants for Titan's ionosphere: Empirical estimates and comparisons with Venus

Author

Cravens, T. E., primary, Richard, M., additional, Ma, Y.-J., additional, Bertucci, C., additional, Luhmann, J. G., additional, Ledvina, S., additional, Robertson, I. P., additional, Wahlund, J.-E., additional, Ågren, K., additional, Cui, J., additional, Muller-Wodarg, I., additional, Waite, J. H., additional, Dougherty, M., additional, Bell, J., additional, and Ulusen, D., additional

Published
2010
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25. A comparison of global models for the solar wind interaction with Mars

Author

Brain, D., primary, Barabash, S., additional, Boesswetter, A., additional, Bougher, S., additional, Brecht, S., additional, Chanteur, G., additional, Hurley, D., additional, Dubinin, E., additional, Fang, X., additional, Fraenz, M., additional, Halekas, J., additional, Harnett, E., additional, Holmstrom, M., additional, Kallio, E., additional, Lammer, H., additional, Ledvina, S., additional, Liemohn, M., additional, Liu, K., additional, Luhmann, J., additional, Ma, Y., additional, Modolo, R., additional, Nagy, A., additional, Motschmann, U., additional, Nilsson, H., additional, Shinagawa, H., additional, Simon, S., additional, and Terada, N., additional

Published
2010
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28. TandEM: Titan and Enceladus mission

Author

Coustenis, A., primary, Atreya, S. K., additional, Balint, T., additional, Brown, R. H., additional, Dougherty, M. K., additional, Ferri, F., additional, Fulchignoni, M., additional, Gautier, D., additional, Gowen, R. A., additional, Griffith, C. A., additional, Gurvits, L. I., additional, Jaumann, R., additional, Langevin, Y., additional, Leese, M. R., additional, Lunine, J. I., additional, McKay, C. P., additional, Moussas, X., additional, Müller-Wodarg, I., additional, Neubauer, F., additional, Owen, T. C., additional, Raulin, F., additional, Sittler, E. C., additional, Sohl, F., additional, Sotin, C., additional, Tobie, G., additional, Tokano, T., additional, Turtle, E. P., additional, Wahlund, J.-E., additional, Waite, J. H., additional, Baines, K. H., additional, Blamont, J., additional, Coates, A. J., additional, Dandouras, I., additional, Krimigis, T., additional, Lellouch, E., additional, Lorenz, R. D., additional, Morse, A., additional, Porco, C. C., additional, Hirtzig, M., additional, Saur, J., additional, Spilker, T., additional, Zarnecki, J. C., additional, Choi, E., additional, Achilleos, N., additional, Amils, R., additional, Annan, P., additional, Atkinson, D. H., additional, Bénilan, Y., additional, Bertucci, C., additional, Bézard, B., additional, Bjoraker, G. L., additional, Blanc, M., additional, Boireau, L., additional, Bouman, J., additional, Cabane, M., additional, Capria, M. T., additional, Chassefière, E., additional, Coll, P., additional, Combes, M., additional, Cooper, J. F., additional, Coradini, A., additional, Crary, F., additional, Cravens, T., additional, Daglis, I. A., additional, de Angelis, E., additional, de Bergh, C., additional, de Pater, I., additional, Dunford, C., additional, Durry, G., additional, Dutuit, O., additional, Fairbrother, D., additional, Flasar, F. M., additional, Fortes, A. D., additional, Frampton, R., additional, Fujimoto, M., additional, Galand, M., additional, Grasset, O., additional, Grott, M., additional, Haltigin, T., additional, Herique, A., additional, Hersant, F., additional, Hussmann, H., additional, Ip, W., additional, Johnson, R., additional, Kallio, E., additional, Kempf, S., additional, Knapmeyer, M., additional, Kofman, W., additional, Koop, R., additional, Kostiuk, T., additional, Krupp, N., additional, Küppers, M., additional, Lammer, H., additional, Lara, L.-M., additional, Lavvas, P., additional, Le Mouélic, S., additional, Lebonnois, S., additional, Ledvina, S., additional, Li, J., additional, Livengood, T. A., additional, Lopes, R. M., additional, Lopez-Moreno, J.-J., additional, Luz, D., additional, Mahaffy, P. R., additional, Mall, U., additional, Martinez-Frias, J., additional, Marty, B., additional, McCord, T., additional, Menor Salvan, C., additional, Milillo, A., additional, Mitchell, D. G., additional, Modolo, R., additional, Mousis, O., additional, Nakamura, M., additional, Neish, C. D., additional, Nixon, C. A., additional, Nna Mvondo, D., additional, Orton, G., additional, Paetzold, M., additional, Pitman, J., additional, Pogrebenko, S., additional, Pollard, W., additional, Prieto-Ballesteros, O., additional, Rannou, P., additional, Reh, K., additional, Richter, L., additional, Robb, F. T., additional, Rodrigo, R., additional, Rodriguez, S., additional, Romani, P., additional, Ruiz Bermejo, M., additional, Sarris, E. T., additional, Schenk, P., additional, Schmitt, B., additional, Schmitz, N., additional, Schulze-Makuch, D., additional, Schwingenschuh, K., additional, Selig, A., additional, Sicardy, B., additional, Soderblom, L., additional, Spilker, L. J., additional, Stam, D., additional, Steele, A., additional, Stephan, K., additional, Strobel, D. F., additional, Szego, K., additional, Szopa, C., additional, Thissen, R., additional, Tomasko, M. G., additional, Toublanc, D., additional, Vali, H., additional, Vardavas, I., additional, Vuitton, V., additional, West, R. A., additional, Yelle, R., additional, and Young, E. F., additional

Published
2008
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29. Plasma Flow and Related Phenomena in Planetary Aeronomy

Author

Ma, Y.-J., primary, Altwegg, K., additional, Breus, T., additional, Combi, M. R., additional, Cravens, T. E., additional, Kallio, E., additional, Ledvina, S. A., additional, Luhmann, J. G., additional, Miller, S., additional, Nagy, A. F., additional, Ridley, A. J., additional, and Strobel, D. F., additional

Published
2008
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32. Composition of Titan's ionosphere

Author

Cravens, T. E., primary, Robertson, I. P., additional, Waite, J. H., additional, Yelle, R. V., additional, Kasprzak, W. T., additional, Keller, C. N., additional, Ledvina, S. A., additional, Niemann, H. B., additional, Luhmann, J. G., additional, McNutt, R. L., additional, Ip, W.-H., additional, De La Haye, V., additional, Mueller-Wodarg, I., additional, Wahlund, J.-E., additional, Anicich, V. G., additional, and Vuitton, V., additional

Published
2006
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33. Titan's ionosphere: Model comparisons with Cassini Ta data

Author

Cravens, T. E., primary, Robertson, I. P., additional, Clark, J., additional, Wahlund, J.-E., additional, Waite, J. H., additional, Ledvina, S. A., additional, Niemann, H. B., additional, Yelle, R. V., additional, Kasprzak, W. T., additional, Luhmann, J. G., additional, McNutt, R. L., additional, Ip, W.-H., additional, De La Haye, V., additional, Müller-Wodarg, I., additional, Young, D. T., additional, and Coates, A. J., additional

Published
2005
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40. FUTURE SPACE PHYSICS AT VENUS.

Author

Collinson, G. A., Fowler, C., Ramstad, R., Curry, S., Chaffin, M., Xu, S., Boucher, S., DiBraccio, G., Dong, C., Futaana, Y., Fillingin, M., Jarvinen, R., Ledvina, S., Luhmann, J., O'Rourke, Joe, Russell, Chris, Persson, Moa, and Way, Michael

Subjects
VENUS (Planet), SOLAR wind, PHYSICS, ELECTRIC field strength, MAGNETIC field measurements, PLANETARY science
Published
2021

44. Ion neutral mass spectrometer results from the first flyby of Titan.

Author

Waite JH Jr, Niemann H, Yelle RV, Kasprzak WT, Cravens TE, Luhmann JG, McNutt RL, Ip WH, Gell D, De La Haye V, Müller-Wordag I, Magee B, Borggren N, Ledvina S, Fletcher G, Walter E, Miller R, Scherer S, Thorpe R, Xu J, Block B, and Arnett K

Subjects
Argon, Atmosphere, Carbon Isotopes, Evolution, Planetary, Extraterrestrial Environment, Hydrogen, Isotopes, Mass Spectrometry, Methane, Nitriles, Nitrogen, Nitrogen Isotopes, Spacecraft, Temperature, Elements, Hydrocarbons, Saturn
Abstract

The Cassini Ion Neutral Mass Spectrometer (INMS) has obtained the first in situ composition measurements of the neutral densities of molecular nitrogen, methane, molecular hydrogen, argon, and a host of stable carbon-nitrile compounds in Titan's upper atmosphere. INMS in situ mass spectrometry has also provided evidence for atmospheric waves in the upper atmosphere and the first direct measurements of isotopes of nitrogen, carbon, and argon, which reveal interesting clues about the evolution of the atmosphere. The bulk composition and thermal structure of the moon's upper atmosphere do not appear to have changed considerably since the Voyager 1 flyby.

Published
2005
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