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R.A. Simpson, G.L. Tyler (Stanford University), M. Paetzold (University of Cologne)
Bistatic radar, conducted at microwave frequencies, can be a convenient and cost-effective method for probing planetary surfaces at centimeter scales - dimensions of interest in selecting lander and rover sites, for example. Half a dozen such experiments have been conducted using Mars Express in a new mode, which relies on relative echo strengths in two orthogonal polarizations rather than absolute calibration of a single polarization (see Simpson and Tyler, ICARUS 152, pp 70-74, 2001). Observations conducted to date have been limited to a fixed spacecraft attitude (inertial pointing); so dielectric constant estimates are valid at only one specular point per wavelength per experiment. Preliminary results have been obtained for Vastitas Borealis (64.1N, 60.1E), the southeast rim of Argyre (56.0S, 324.8E), and plains west of Argyre (51.0S, 289.4E). Dielectric constants are N/A and 2.7, 2.0 and 2.1, and 3.2 and 3.5 at the three sites at 3.5 and 13.1 cm wavelengths, respectively. These confirm spatial variability (while being within the nominal range for Mars) and show the expected lower values at shorter wavelengths.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.