Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 27, 4257-4272, 2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
16 Nov 2009
Titan's ionosphere in the magnetosheath: Cassini RPWS results during the T32 flyby
P. Garnier1,2,3, J-E. Wahlund1, L. Rosenqvist1, R. Modolo1, K. Ågren1, N. Sergis4, P. Canu5, M. Andre1, D. A. Gurnett6, W. S. Kurth6, S. M. Krimigis7, A. Coates8, M. Dougherty9, and J. H. Waite10 1Swedish Institute of Space Physics, P.O. Box 537, 751 21 Uppsala, Sweden
2Universite de Toulouse, UPS, CESR, 9 ave colonel Roche, 31028 Toulouse cedex 9, France
3CNRS, UMR5187, 31028 Toulouse, France
4Office for Space Research and Applications, Academy of Athens, Athens, Greece
5Centre d'Etudes des Environnements Terrestre et Planetaires, Institut Pierre Simon Laplace, Velizy, France
6Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
7Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA
8Mullard Space Science Laboratory, University College London, Dorking, UK
9Space and Atmospheric Physics group, Imperial College London, Prince Consort Road, London SW7 2AZ, UK
10Space Science and Engineering Division, Southwest Research Inst., P.O. Drawer 28510, San Antonio, TX 78228-0510, USA
Abstract. The Cassini mission has provided much information about the Titan environment, with numerous low altitude encounters with the moon being always inside the magnetosphere. The only encounter taking place outside the magnetopause, in the magnetosheath, occurred the 13 June 2007 (T32 flyby). This paper is dedicated to the analysis of the Radio and Plasma Wave investigation data during this specific encounter, in particular with the Langmuir probe, providing a detailed picture of the cold plasma environment and of Titan's ionosphere with these unique plasma conditions. The various pressure terms were also calculated during the flyby. The comparison with the T30 flyby, whose geometry was very similar to the T32 encounter but where Titan was immersed in the kronian magnetosphere, reveals that the evolution of the incident plasma has a significant influence on the structure of the ionosphere, with in particular a change of the exo-ionospheric shape. The electrical conductivities are given along the trajectory of the spacecraft and the discovery of a polar plasma cavity is reported.

Citation: Garnier, P., Wahlund, J.-E., Rosenqvist, L., Modolo, R., Ågren, K., Sergis, N., Canu, P., Andre, M., Gurnett, D. A., Kurth, W. S., Krimigis, S. M., Coates, A., Dougherty, M., and Waite, J. H.: Titan's ionosphere in the magnetosheath: Cassini RPWS results during the T32 flyby, Ann. Geophys., 27, 4257-4272, doi:10.5194/angeo-27-4257-2009, 2009.
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