Superthermal Electron Observations at Mars During the December 2022 Disappearing Solar Wind Event

On 26–27 December 2022, Mars experienced an extremely low‐density solar wind stream, which was encountered first by Earth because of the radial alignment of the two planets (i.e., Mars opposition). During this event, two important properties of the ionospheric and magnetospheric states changed signi...

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Bibliographic Details
Published in:Journal of geophysical research. Space physics 2024-02, Vol.129 (2), p.n/a
Main Authors: Xu, Shaosui, Mitchell, David L., Halekas, Jasper, Brain, David A., Weber, Tristan, Andersson, Laila, Shaver, Skylar, Azari, Abigail, McFadden, James P., Hanley, Kathleen, Ma, Yingjuan, Lee, Christina, DiBraccio, Gina A., Mazelle, Christian, Curry, Shannon M.
Format: Article
Language:English
Subjects:
ambipolar potential
disappearing solar wind event
Electron pressure
Ionosphere
Ionospheric electrons
Lower ionosphere
Magnetic properties
magnetic topology
Magnetospheres
Mars
Mars missions
Pressure gradients
Ram pressure
Solar wind
Sun‐Mars interaction
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Summary:On 26–27 December 2022, Mars experienced an extremely low‐density solar wind stream, which was encountered first by Earth because of the radial alignment of the two planets (i.e., Mars opposition). During this event, two important properties of the ionospheric and magnetospheric states changed significantly in response to the low solar wind ram pressure, as inferred from the superthermal electron observations from the Mars Atmospheric and Volatile EvolutioN (MAVEN) mission. The interface between the ionosphere and magnetosphere expanded to thousands of kilometers, outside of the nominal bow shock locations, coinciding with the expansion of the cold planetary ions. Meanwhile, the ambipolar electrostatic potential arising from the ionospheric electron pressure gradient increased from the nominal ∼ −0.7 to ∼ −2 V (relative to the lower ionosphere). This enhanced ambipolar potential likely facilitated the observed ionosphere expansion. Key Points This study characterizes Mars's magnetospheric and ionospheric response to the disappearing solar wind event in December 2022 During the event, open and closed field lines extend beyond the nominal bow shock location, just as the planetary cold ions The ionospheric ambipolar potential drop is enhanced from the nominal ∼ −0.7 to ∼ −2 V, likely facilitating the ionosphere expansion
ISSN:2169-9380
2169-9402
DOI:10.1029/2023JA032258