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MAVEN Observations of H Ions in the Martian Atmosphere

Abstract : At Mars, charge exchange between solar wind protons and neutral exospheric hydrogen produces energetic neutral atoms (ENAs) that can penetrate into the collisional atmosphere, where they can be converted through collisions into H+ and H. The Mars Atmosphere and Volatile EvolutioN mission observed a population of negatively charged particles at low altitudes, whose energies, angular distribution, and dependence on the upstream solar wind were consistent with H produced by solar wind hydrogen ENAs. The highest fluxes of H were observed near perihelion and the southern summer solstice. We calculated an average ratio of ∼4% between H density and H+ density, implying a slightly smaller relative abundance than reported previously (∼10%). We found that the fraction of H ENAs converted to H increases with the solar wind energy, in agreement with laboratory measurements of the H-CO2 electron capture cross section.
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Submitted on : Wednesday, November 23, 2022 - 1:19:17 PM
Last modification on : Thursday, November 24, 2022 - 4:04:56 AM




N. Jones, J. Halekas, Z. Girazian, D. Mitchell, C. Mazelle. MAVEN Observations of H Ions in the Martian Atmosphere. Journal of Geophysical Research: Planets, 2022, 127, ⟨10.1029/2021JE006999⟩. ⟨insu-03867484⟩



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