Mass composition of the escaping plasma at Mars

E. Carlsson*, A. Fedorov, S. Barabash, E. Budnik, A. Grigoriev, H. Gunell, H. Nilsson, J. A. Sauvaud, R. Lundin, Y. Futaana, M. Holmström, H. Andersson, M. Yamauchi, J. D. Winningham, R. A. Frahm, J. R. Sharber, J. Scherrer, A. J. Coates, D. R. Linder, D. O. KatariaE. Kallio, H. Koskinen, T. Säles, P. Riihelä, W. Schmidt, J. Kozyra, J. Luhmann, E. Roelof, D. Williams, S. Livi, C. C. Curtis, K. C. Hsieh, B. R. Sandel, M. Grande, M. Carter, J. J. Thocaven, S. McKenna-Lawler, S. Orsini, R. Cerulli-Irelli, M. Maggi, P. Wurz, P. Bochsler, N. Krupp, J. Woch, M. Fränz, K. Asamura, C. Dierker

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

90 Citations (SciVal)


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 4.0 × 1024 s-1 ( 0.29   kg s-1 ) 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.

Original languageEnglish
Pages (from-to)320-328
Number of pages9
Issue number2
Publication statusPublished - Jun 2006


  • atmosphere
  • Ionospheres
  • Mars


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