HR: 16:30h
AN: P14B-03    [Abstracts]
TI: An Overview of MARSIS and SHARAD Radar Sounding Observations of the Polar Deposits of Mars
AU: * Plaut, J J
EM: plaut@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109,
AU: Picardi, G
EM: picar@infocom.uniroma1.it
AF: University of Rome "La Sapienza", INFOCOM Department, Via Eudossiana, 18, Rome, 00184, Italy
AU: Seu, R
EM: robseu@infocom.uniroma1.it
AF: University of Rome "La Sapienza", INFOCOM Department, Via Eudossiana, 18, Rome, 00184, Italy
AU: Phillips, R
EM: phillips@wurtzite.wustl.edu
AF: Washington University, Department of Earth and Planetary Sciences, Brookings Dr., St. Louis, MO 63130,
AU: Biccari, D
EM: d.biccari@infocom.uniroma1.it
AF: University of Rome "La Sapienza", INFOCOM Department, Via Eudossiana, 18, Rome, 00184, Italy
AU: Holt, J
EM: jack@utig.ig.utexas.edu
AF: U. Texas, Inst. for Geophysics, Jackson School of Geosciences, Austin, TX 78713,
AU: Milkovich, S
EM: smmilkov@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109,
AU: Orosei, R
EM: Roberto.Orosei@rm.iasf.cnr.it
AF: Istituto Nazionale di Astrofisica, Istituto di Astrofisica Spaziale e Fisica Cosmica, Rome, 00133, Italy
AU: Putzig, N
EM: than@putzig.com
AF: Washington University, Department of Earth and Planetary Sciences, Brookings Dr., St. Louis, MO 63130,
AU: Safaeinili, A
EM: ali.safaeinili@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109,
AB: A recent development in the exploration of Mars has been the deployment of two orbital subsurface radar sounding instruments, MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) on Mars Express, and SHARAD (Shallow Radar) on the Mars Reconnaissance Orbiter. Both experiments are fully operational, MARSIS since July 2005, and SHARAD since October 2006. The two radars are complementary, with MARSIS operating at deep-sounding low frequencies (2-5 MHz) with low vertical resolution (100 m), and SHARAD operating at a shallower-sounding higher frequency (15-25 MHz), but with much higher vertical resolution (10 m). The materials on Mars that are most consistently amenable to subsurface sounding are found in the polar regions. These include the several-km-thick, water-ice-rich polar layered deposits (PLD), and in the south, a surrounding ancient sedimentary terrain known as the Dorsa Argentea Formation. MARSIS sounding of the PLD consistently reaches the base of the deposits, to an interface between the ice-rich PLD materials and a presumably less ice-rich lithic substrate. This interface lies at a maximum depth of more than 3 km in both polar regions. The signal power reflected at the basal interface indicates minimal attenuation in the PLD material, consistent with a sediment-poor (less than 0.1) composition. No evidence is seen of liquid zones at the PLD base. Internal banding related to the layered structure of the deposits is observed in both MARSIS and SHARAD data, with the high vertical resolution SHARAD data revealing spectacular detail. Preliminary correlation of the internal radar banding with optical images of exposed layers indicates the bands are related to packets of layers that show a consistent erosional style in outcrop. SHARAD data show clear evidence of erosional unconformities, but evidence of deformation due to flow is sparse at best. In the north PLD, MARSIS data commonly show a diffusely reflecting layer above the basal interface. The SHARAD signal only partially penetrates this lower layer. The map distribution and thickness of this radar layer suggest a correlation with the previously recognized "basal unit" that in optical images appears to have a large component of incorporated sediment.
DE: 5422 Ices
DE: 5462 Polar regions
DE: 5464 Remote sensing
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting