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Electric Mars: A large trans‐terminator electric potential drop on closed magnetic field lines above Utopia Planitia
Author(s) -
Collinson Glyn,
Mitchell David,
Xu Shaosui,
Glocer Alex,
Grebowsky Joseph,
Hara Takuya,
Lillis Robert,
Espley Jared,
Mazelle Christian,
Sauvaud JeanAndré,
Fedorov Andrey,
Liemohn Mike,
Andersson Laila,
Jakosky Bruce
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023589
Subject(s) - mars exploration program , electric field , terminator (solar) , geophysics , martian , ionosphere , geology , magnetic field , physics , atmosphere of mars , astrobiology , solar wind , atmospheric sciences , geodesy , quantum mechanics
Parallel electric fields and their associated electric potential structures play a crucial role in ionospheric‐magnetospheric interactions at any planet. Although there is abundant evidence that parallel electric fields play key roles in Martian ionospheric outflow and auroral electron acceleration, the fields themselves are challenging to directly measure due to their relatively weak nature. Using measurements by the Solar Wind Electron Analyzer instrument aboard the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) Mars Scout, we present the discovery and measurement of a substantial (Φ Mars =7.7 ± 0.6 V) parallel electric potential drop on closed magnetic field lines spanning the terminator from day to night above the great impact basin of Utopia Planitia, a region largely free of crustal magnetic fields. A survey of the previous 26 orbits passing over a range of longitudes revealed similar signatures on seven orbits, with a mean potential drop (Φ Mars ) of 10.9 ± 0.8 V, suggestive that although trans‐terminator electric fields of comparable strength are not ubiquitous, they may be common, at least at these northerly latitudes.