Journal article
The Influence of Solar Wind Pressure on Martian Crustal Magnetic Field Topology
Geophysical research letters, Vol.46(5), pp.2347-2354
03/16/2019
DOI: 10.1029/2019GL081913
Abstract
We present a study of changes in Martian magnetic topology induced by upstream solar wind ram pressure variations. Using electron energy spectra and pitch angle distributions measured by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we classify the topology of magnetic field lines in the Martian space environment across a range of solar wind conditions. We find that during periods of high solar wind dynamic pressure, draped fields are pushed to lower altitudes on the dayside of the planet, compressing closed fields. At the same time, open topology becomes more prevalent on the nightside due to the broadening of crustal cusp regions. The result is a decrease in closed topology at all locations around Mars, suggesting that the Martian ionosphere becomes significantly more exposed to solar wind energy input during high solar wind pressure. This could likely contribute to elevated levels of ion escape during these periods.
Plain Language Summary
Planetary atmospheres are constantly bombarded by energy and radiation from the Sun, and over time this energy input can strip away an atmosphere to space. This process has been particularly devastating at Mars, where the loss of most of its original atmosphere has left the planet cold and desolate. This loss may have been in part due to the planet's lack of a global magnetic field. While the Earth possesses a large magnetic field that diverts much of the solar energy input, Mars does not. However, Mars does possess smaller pockets of magnetic field that are rooted in the planet's crust and extend outward through the atmosphere, a unique feature in the solar system. These magnetic fields are able to shield Mars's atmosphere on a small scale but are susceptible to changes in the strength of solar activity. Here we show that during these periods of increased solar output, the magnetic pockets across Mars are compressed to a smaller size, leaving the planet's atmosphere more exposed and more likely to escape to space.
Key Points
High solar wind pressure decreases the presence of closed topology across Mars
On the dayside, draped fields extend to lower altitudes during high solar wind pressure
On the nightside, crustal cusps with open topology expand during high solar wind pressure
Details
- Title: Subtitle
- The Influence of Solar Wind Pressure on Martian Crustal Magnetic Field Topology
- Creators
- Tristan Weber - Laboratory for Atmospheric and Space PhysicsDavid Brain - Space Science InstituteDavid Mitchell - Space Science InstituteShaosui Xu - Space Science InstituteJared Espley - Goddard Space Flight CenterJasper Halekas - University of IowaRobert Lillis - Space Science InstituteBruce Jakosky - Laboratory for Atmospheric and Space Physics
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.46(5), pp.2347-2354
- DOI
- 10.1029/2019GL081913
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 8
- Grant note
- NASA Earth and Space Science Fellowship (80NSSC18K1247)
- Language
- English
- Date published
- 03/16/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428780002771
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