New Radar Observations of Terra Meridiani, Mars.

Over the course of three months bracketing the latest Mars opposition (June 21, 2001) a series of fourteen ground-based radar observation sequences were performed. An X-band (3.5 cm) radar signal was transmitted from the main 70-meter telescope (DSS-14) at the Goldstone Deep Space Network complex and the reflected signal recorded by four radio telescopes (DSS-12, DSS-13, DSS-14, and DSS-25). The observation tracks fall within four regions on Mars; Isidis Planitia, Syrtis Major, the "Stealth" region, and Terra Meridiani. Our processing has focused on the Terra Meridiani tracks as this is currently an area of great interest due to the detection of gray hematite, from Mars Global Surveyor Thermal Emission Spectrometer results [Christensen, 2000], and its status as a leading landing site candidate for the 2003 Mars Exploration Rover (MER) mission. We are using a Maximum Likelihood Function (MLF) algorithm that models the backscatter radiation according to Hagfors' model and allows determination of the local surface roughness, or RMS slope on the scale of several wavelengths, and the surface dielectric constant. New to this analysis is the use of four recording stations, which doubles the number of observational baselines available to earlier three-station interferometry and thus the number of cross-power inputs into the probabilistic MLF formulation. We also have incorporated the Mars Global Surveyor MOLA topographic data set which eliminated range as an unknown in our solution, allowing for a more precise determination of the RMS slope and dielectric constants. We will present maps of the RMS slope and dielectric constant for the Terra Meridiani observations.