Modelling the interaction of Phobos' surface with the Solar Wind and Martian environment
Résumé
Indirect evidence of a gas/dust tori along Phobos
orbit has been inferred from data gathered during
Viking orbiter and Phobos-2 missions (Ip and
Banaszkiewicz 1990, Dubinin et al 1990), but
never confirmed. Since Phobos’ surface is directly
exposed to the solar wind the structure and
chemical nature of such tori would primarily
depend on Phobos surface composition, which is
in turn largely unknown, even though some
proximity with D type asteroids can be inferred
(Rivkin et al 2002).
In this study we carry out 3D Monte Carlo
simulation of the interaction of Phobos surface
with the Solar Wind and Martian environment.
Such simulations intend to give information on the
relative variability of the degassing rate of Phobos’
surface along Phobos’ orbit, based on different
hypothesis on Phobos surface compositions
(primitive carbon-rich or olivine rich), and
describe the morphology of the cloud resulting
from the ejection of neutral species along Phobos
orbit.
Since Phobos’ circular orbit is located
approximately 6000 km above the surface, we
consider and compare the efficiency of a variety of
degassing processes (solar wind ions and electrons
sputtering, martian exospheric picked up ions
sputtering, micrometeorites vaporization, photo-
stimulated desorption) according to the region
(solar wind, dayside/nightside, magnetosphere)
crossed by Phobos around Mars.