Journal article
Plasma clouds and snowplows: Bulk plasma escape from Mars observed by MAVEN
Geophysical research letters, Vol.43(4), pp.1426-1434
02/28/2016
DOI: 10.1002/2016GL067752
Abstract
We present initial Mars Atmosphere and Volatile EvolutioN (MAVEN) observations and preliminary interpretation of bulk plasma loss from Mars. MAVEN particle and field measurements show that planetary heavy ions derived from the Martian atmosphere can escape in the form of discrete coherent structures or “clouds.” The ions in these clouds are unmagnetized or weakly magnetized, have velocities well above the escape speed, and lie directly downstream from magnetic field amplifications, suggesting a “snowplow” effect. This postulated escape process, similar to that successfully used to explain the dynamics of active gas releases in the solar wind and terrestrial magnetosheath, relies on momentum transfer from the shocked solar wind protons to the planetary heavy ions, with the electrons and magnetic field acting as intermediaries. Fluxes of planetary ions on the order of 107 cm−2 s−1 can escape by this process, and if it operates regularly, it could contribute 10–20% of the current ion escape from Mars.
Key Points
Ionospheric plasma can escape from Mars in coherent structures or clouds
Momentum is transferred from the solar wind to heavy ions by magnetic fields
A snowplow effect accelerates parcels of unmagnetized Martian plasma
Details
- Title: Subtitle
- Plasma clouds and snowplows: Bulk plasma escape from Mars observed by MAVEN
- Creators
- J. S Halekas - University of IowaD. A Brain - University of Colorado BoulderS Ruhunusiri - University of IowaJ. P McFadden - University of California, BerkeleyD. L Mitchell - University of California, BerkeleyC Mazelle - L'Institut de Recherche en Astrophysique et Planétologie Toulouse FranceJ. E. P Connerney - Goddard Space Flight CenterY Harada - University of California, BerkeleyT Hara - University of California, BerkeleyJ. R Espley - Goddard Space Flight CenterG.A DiBraccio - Goddard Space Flight CenterB. M Jakosky - University of Colorado Boulder
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.43(4), pp.1426-1434
- DOI
- 10.1002/2016GL067752
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 9
- Language
- English
- Date published
- 02/28/2016
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199782402771
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