Journal article
Piercing the Martian Veil: A Statistical Study of Interplanetary Magnetic Field Reach Through Ionospheric Pressure Balance
Journal of geophysical research. Space physics, Vol.130(2), e2024JA033254
02/2025
DOI: 10.1029/2024JA033254
Abstract
Mars, being a small planet with a tenuous atmosphere, does not have a sharp boundary between regions dominated by solar wind plasma and planetary plasma. Instead, this transition is typically extended, allowing the interplanetary magnetic field (IMF) to penetrate into the Martian ionosphere. However, the depth of this penetration is not well understood. Using 6 years of MAVEN data, we statistically assess locations where a transition exists between the dominance of magnetic versus cold (1 eV), thermal plasma pressure to better understand the reach of the IMF. We identify the presence or absence of pressure transitions from 200 to 800 km altitude for each MAVEN orbit and find a clear transition in 55% of cases. The pressure transition locations are mapped in different coordinate systems that provide insight into the solar and planetary driving conditions that cause a detected transition region. Transitions are more likely to occur under weak‐to‐nominal solar wind conditions, away from strong crustal magnetic fields, near the terminator, on the dusk side of the planet compared to the dawn side, and in the negative solar wind motional electric field hemisphere. We speculate on possible causes for asymmetries that arise in the mapped locations of these pressure transitions and the effect that penetrated IMF may have on driving plasma dynamics in the Martian ionosphere.
The Sun emits a constant stream of charged particles known as the solar wind. These particles carry a magnetic field as they move through the solar system. When sunlight hits the thin atmosphere of Mars, it causes the atmospheric particles to become electrically charged, creating the Martian ionosphere. When the solar wind interacts with the Martian ionosphere, it causes currents to flow that divert the solar wind particles around Mars. However, the magnetic field carried by the solar wind can penetrate further into the Martian atmosphere, leading to mass, momentum, and energy exchange between the solar wind and the planet's atmosphere. To better understand the penetration of the solar wind's magnetic field into the Martian atmosphere, we study locations where magnetic pressure and thermal ionospheric pressure are balanced. These locations are assumed to mark the transition between a region where the penetrated solar magnetic field drives plasma motion, to a region where the motions of Martian ionospheric particles dominate plasma dynamics. This will help future studies determine how far into the atmosphere electromagnetic forces can drive dynamics.
Pressure transitions between 200 and 800 km are only observed on roughly 55% of the orbits studied Pressure transitions are dominantly absent over strong crustal magnetic fields in the region studied Occurrence increases under weak‐to‐nominal solar wind conditions, on the dusk side, and in the negative motional electric field hemisphere
Details
- Title: Subtitle
- Piercing the Martian Veil: A Statistical Study of Interplanetary Magnetic Field Reach Through Ionospheric Pressure Balance
- Creators
- S. R. Shaver - Laboratory for Atmospheric and Space PhysicsL. Andersson - University of Colorado BoulderR. Ramstad - University of Colorado BoulderBhagyashree Waghule - University of Colorado BoulderD. Brain - Laboratory for Atmospheric and Space PhysicsR. Lillis - University of California, BerkeleyT. Cravens - University of KansasJ. Halekas - University of IowaS. Xu - University of California, BerkeleyP. C. Hinton - Laboratory for Atmospheric and Space PhysicsD. Malaspina - Laboratory for Atmospheric and Space PhysicsM. W. Liemohn - University of Michigan–Ann ArborS. Ledvina - University of California, BerkeleyJ. R. Gruesbeck - University of Maryland, College ParkS. Curry - Laboratory for Atmospheric and Space Physics
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.130(2), e2024JA033254
- Publisher
- AMER GEOPHYSICAL UNION
- DOI
- 10.1029/2024JA033254
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Grant note
- NASA MAVEN: NNH10CC04C NASA
We acknowledge NASA and the MAVEN mission for support partially through Grant NNH10CC04C to the University of Colorado and by subcontract to Space Sciences Laboratory, University of California, Berkeley. The authors would like to express their gratitude to the two anonymous reviewers for their invaluable discussions, time, and effort in enhancing this work.
- Language
- English
- Date published
- 02/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984787176002771
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