Space Weathering of Icy Volatiles within North Polar Permanently Shadowed Regions |
Auteur | Schriver David |
Institution | UCLA |
Theme | Theme1 |
| Auteur(s) supplémentaire(s) | Travnicek P. (2), Delitsky M. (3), Ho G. (4), Echterling N. (5) |
| Institution(s) supplémentaire(s) | (1) Department of Physics and Astronomy, UCLA, CA (2) Space Sciences Laboratory, University of California, Berkeley, CA (3) California Specialty Engineering, Pasadena, CA (4) Johns Hopkins University Applied Physics Laboratory, Laurel, MD (5) Department of Earth, Planetary and Space Science, UCLA, CA |
|
Abstract | Mercury has an intrinsic magnetic field which generates a magnetosphere around the planet. The
solar wind interacts with Mercury~s magnetosphere causing the formation of large-scale structures
known as magnetic cusps, which are funnel-shaped areas of focused magnetic field that converge
toward the dayside planetary surface at high latitudes. Magnetospheric dynamical processes result
in the cusp being filled with energetic charged particles and because Mercury lacks an atmosphere
or ionosphere, these energetic ions and electrons are funneled down the cusp precipitating directly
onto the surface of the planet. The latitudinal location of the cusp footprint on the planet varies
with solar wind conditions, in particular with the interplanetary magnetic field (IMF) direction.
Since Mercury's internal magnetic dipole is offset to the north by about 480 km, when the IMF is
directed northward the northern cusp moves to very high latitudes greater 75 degrees, mapping
directly onto the northern polar region. Craters near the poles contain permanently shadowed
regions (PSRs) which allow frozen water ice mixed with organic molecules to exist over long
timescales. The energetic precipitating particles can induce chemical radiation processing of the
icy volatiles into higher-order organics and dark refractory materials overlaying the water ice.
Global kinetic magnetospheric simulations in conjunction with MESSENGER spacecraft data are
used to characterize the fluxes and energies of the precipitating particles in Mercury's
magnetospheric cusp region and the resulting space weathering interactions with the icy volatiles
in the PSRs at high northern latitudes. MESSENGER data and numerical simulation results will
be presented along with a discussion of the data gaps expected to be filled by BepiColombo
observations. |
