• Aurorae: Caused by accelerated charged particles
precipitating along magnetic field lines into a planetary
atmosphere - the auroral brightness is roughly proportional to
the precipitating particle energy flux.
• The Analyzer of Space Plasma and Energetic Atoms
(ASPERA-3) experiment on the Mars Express spacecraft has
made a detailed study of acceleration processes on the
nightside of Mars.
• We observe accelerated electrons and ions in the deep
nightside high altitude region of Mars that map geographically
to interface/cleft regions associated with Martian crustal
magnetization regions
Orbit track of spacecraft in latitude and east longitude coordinates showing the traversal of an
“inverted V” event (dashed line) adjacent to a crustal magnetic field anomaly (dark region).
Map of crustal magnetic field at 400 km marking ion
and electron acceleration (“inverted V”) events. All
events occurring close to local midnight
Acceleration and guidance of ions and electrons
along crustal magnetic field lines at Mars
Cusp/cleft aurora is expected to occur between adjacent anomalies and
halo aurora circumscribing the large-scale region of crustal magnetization
Daytime and nighttime - map of Mars
Conclusions
Auroral particle acceleration over Mars
• Upward accelerated ions and downward accelerated
electrons are observed near local midnight, on flux tubes
connecting to strong crustal magnetizations. Strong
similarities with auroral plasma acceleration near the Earth
⇒ Discrete aurorae likely in boundaries interfacing crustal
magnetization regions at Mars.
• Aurora on Mars should form complex patterns over the
nightside southern hemisphere, near the equator (compare
with polar aurora over the Earth).
⇒ Aurora on Mars cannot be observed from the Earth (like
polar aurora on e.g. Jupiter and Saturn
http://www.cosis.net/abstracts/EGU06/02847/EGU06-J-02847.pdf