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Magnetosphere of Mars at Almost Radial Interplanetary Magnetic Field
Journal article   Open access   Peer reviewed

Magnetosphere of Mars at Almost Radial Interplanetary Magnetic Field

E. Dubinin, R. Modolo, M. Fraenz, M. Pätzold, S. Tellmann, G. DiBraccio, J. Halekas, J. McFadden, R. Lin and S. Huang
Journal of geophysical research : Space physics (2013 - Present), Vol.131(4), e2026JA035038
04/01/2026
DOI: 10.1029/2026JA035038
url
https://doi.org/10.1029/2026JA035038View
Published (Version of record) Open Access

Abstract

We have studied the structure of the Martian magnetosphere under conditions of an almost radial interplanetary magnetic field (IMF). Under such conditions, the currents driven by the motional electric field (Formula presented.) are expected to be strongly reduced, and the induced magnetosphere may degenerate. We analyzed Mars Atmosphere and Volatile EvolutioN (MAVEN) data for orbits during which the IMF cone angle was below (Formula presented.) or larger than (Formula presented.). We find that the main features of the Martian magnetosphere, observed for the nominal Parker spiral IMF configuration at Mars' orbit, remain present even for nearly field-aligned plasma flow. The IMF cone angle begins to change at the bow shock, exhibiting large fluctuations but with a clear tendency for the magnetic field lines to envelop the ionospheric obstacle. This process is accompanied by a pileup of the magnetic field and the formation of a magnetic barrier that balances the thermal pressure of the shocked solar wind. Only on very rare orbits do we observe sunward ejection of ions from the ionosphere and their strong interaction with the solar wind. Not a perfect alignment of the IMF and the solar wind flow and the existence of a strong crustal magnetic field are probably responsible for a creation of the magnetosphere even at such a geometry.
 Ionosphere interplanetary magnetic field magnetosphere Mars plasma solar wind

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