The precipitation of keV energetic oxygen ions at Mars and their effects during the comet Siding Spring approach

Research output: Contribution to journalArticleScientificpeer-review


  • Guillaume Gronoff
  • Ali Rahmati
  • Cyril Simon Wedlund
  • Christopher J. Mertens
  • Thomas E Cravens
  • Esa Kallio

Research units


Comet Siding Spring C/2013 A1 will pass Mars on 19 October 2014, entailing particle and dust precipitation in the Martian upper atmosphere and a potential dust hazard for orbiters. An estimate of the flux of energetic O+ ions picked up by the solar wind from the cometary coma is shown, with an increase of the O+ flux above 50 keV by 2 orders of magnitude. While the ionization of Mars’ upper atmosphere by precipitating O+ ions is expected to be negligible compared to solar EUV-XUV ionization, it is of the same order of magnitude at 110 km altitude during the cometary passage, leading to detectable increases in ionospheric densities. Cometary O+ pickup ion precipitation is expected to be the major nightside ionization source, creating a temporary ionosphere and a global airglow. These effects are dependent on the solar and cometary activities at the time of the encounter.


Original languageEnglish
Pages (from-to)4844-4850
JournalGeophysical Research Letters
Issue number14
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed

    Research areas

  • comet, Mars, O+, pickup

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