Transient Density Enhancements of the Martian Orbiting Dust Torus

Abstract:

The moons Phobos and Deimos have been suggested to be responsible for sustaining
a permanently present dust cloud around Mars. The equilibrium size and spatial
distribution of this dust torus has been the subject of numerous theoretical
studies. However, no observational evidence has been found as of yet.
Because of the renewed interest in Phobos and Deimos as potential targets for
human precursor mission to Mars, there is a new opportunity for the detection of
the putative Martian dust clouds using in situ measurements. Both Phobos and
Deimos, as all airless bodies in the solar system, are continually bombarded by
interplanetary dust grains, generating secondary ejecta particles. The surface
gravity escape of these objects are low, hence most secondary particles escape
them, but remain in orbit about Mars. Subsequent perturbations by solar radiation
pressure, electromagnetic forces acting on charged grains, and collisions with
the moons or Mars itself limit the lifetime of the produced particles. The size
dependent production rates and lifetimes set the most abundant particle size
range of 10 - 30 micron in radius. Large, but short-lived, dust density
enhancements can be predicted during periods of meteor showers. Also, comet
Siding Spring will flyby Mars in October, 2014.
Its dust tail can 'sand-blast' both Phobos and Deimos, dramatically increasing
their dust production for a few hours. We present the results of our numerical
studies on the temporal and spatial evolution of the dust clouds raised during
highly enhanced production rates that last only hours-to-days.