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Mass composition of the escaping plasma at Mars |
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| Authors: | E Carlsson A Fedorov E Budnik H Gunell J-A Sauvaud Y Futaana H Andersson JD Winningham JR Sharber AJ Coates DO Kataria H Koskinen P Riihelä J Kozyra E Roelof S Livi KC Hsieh M Grande J-J Thocaven S Orsini M Maggi P Bochsler J Woch K Asamura |
| Institution: | a Swedish Institute of Space Physics, Box 812, SE-981 28 Kiruna, Sweden b Luleå University of Technology, Luleå, Sweden c Centre d'Etude Spatiale des Rayonnements, BP-4346, F-31028 Toulouse, France d Southwest Research Institute, San Antonio, TX 7228-0510, USA e Mullard Space Science Laboratory, University College London, Surrey RH5 6NT, UK f Finnish Meteorological Institute, Box 503, FIN-00101 Helsinki, Finland g Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143, USA h Space Science Laboratory, University of California at Berkeley, Berkeley, CA 94720-7450, USA i Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099, USA j University of Arizona, Tucson, AZ 85721, USA k Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK l Space Technology Ireland, National University of Ireland, Maynooth, Co. Kildare, Ireland m Istituto di Fisica dello Spazio Interplanetari, I-00133 Rome, Italy n Physikalisches Institut, University of Bern, CH-3012 Bern, Switzerland o Max-Planck-Institut für Aeronomie, D-37191 Katlenburg-Lindau, Germany p Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamichara, Japan q Technical University of Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig, Germany |
| Abstract: | Data from the Ion Mass Analyzer (IMA) sensor of the ASPERA-3 instrument suite on Mars Express have been analyzed to determine the mass composition of the escaping ion species at Mars. We have examined 77 different ion-beam events and we present the results in terms of flux ratios between the following ion species: CO+2/O+ and O+2/O+. The following ratios averaged over all events and energies were identified: CO+2/O+ = 0.2 and O+2/O+ = 0.9. The values measured are significantly higher, by a factor of 10 for O+2/O+, than a contemporary modeled ratio for the maximum fluxes which the martian ionosphere can supply. The most abundant ion species was found to be O+, followed by O+2 and CO+2. We estimate the loss of CO+2 to be  by using the previous measurements of Phobos-2 in our calculations. The dependence of the ion ratios in relation to their energy ranges we studied, 0.3-3.0 keV, indicated that no clear correlation was found. |
| Keywords: | Ionospheres Mars atmosphere |
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