HR: 0800h
AN: P11B-0542    [Abstracts]
TI: Parametric Dielectric Map of the Martian North Polar Layered Deposits in Support of the MARSIS and SHARAD data analysis
AU: Cosmidis, J
EM: julie.cosmidis@ens-lyon.fr
AF: Ecole normale supérieure de Lyon, 46, allée d'Italie, Lyon, 69364, France
AU: * Heggy, E
EM: heggy@lpi.usra.edu
AF: Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058, United States
AU: * Heggy, E
EM: heggy@lpi.usra.edu
AF: Institut de Physique du Globe de Paris (CNRS-UMR7154), 4 Avenue de Neptune, Saint Maur, 94107, France
AU: Clifford, S M
EM: clifford@lpi.usra.edu
AF: Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058, United States
AB: Laboratory dielectric characterizations of Ice-dust mixtures are crucial for the quantitative analysis of radar sounding data as for the case of the MARSIS and SHARAD experiments. Understanding the range of the dielectric properties of the Martian northmen Polar layer deposits as well as their geographical an vertical distribution result in a better topographical mapping of the basement material below the northern polar cap and help constrain the ambiguities on the identification of layering and any potential subglaciar melting. In order to achieve this task, we constructed first order modeled maps of the surface dielectric properties oh the NPLD. We first used the recent Mars Global Surveyor Thermal Emission Spectrometer (TES) thermal inertia observations in order to derive a map of the dust mass fraction in the ice at the top of the permanent cap. Then we used parametric laboratory measurements of the dielectric properties of Martian polar ice analogs with various temperatures, radar frequencies and mass fractions and compositions of dust in order to obtain the parametric dielectric maps. Thermal inertia maps have been derived from recent TES observations of the surface temperatures of Mars taken over three Mars-years from orbit 1583 to 24346. Laboratory dielectric characterization of ice-dust mixtures has been performed using TES dust calibration samples provided by the ARES group at NASA JSC. Our Maps suggest that surface dielectric properties of the northern Polar cap ranges from 2.72 to 3.23 in the 2-20 MHz band for a dust inclusion typical of Martian basalt. Parametric maps of loss tangent, penetration depth for several dust types will be presented at the conference.
DE: 5134 Thermal properties
DE: 5144 Wave attenuation
DE: 5462 Polar regions
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting