Radar polarization studies of volcanic and impact cratered terrains on the Earth, Venus, and the Moon

This dissertation presents the results of four research projects which utilize imaging radar polarization data for remote sensing of volcanic and impact cratered terrains on the Earth, Venus, and the Moon. Chapter 2 is an analysis of airborne multi-polarization radar data, and develops a technique for decomposing the polarized radar echo into components attributed to quasi-specular, small-perturbation, and "dihedral" mechanisms. Model results are compared to field measurements of surface roughness. The proposed model appears to be a potentially useful remote-sensing technique for analysis of lava flow morphology.; Chapters 3 and 4 analyze the geomorphology and radar polarization properties of deposits on two volcanoes, Sif and Gula Montes, in Western Eistla Regio, Venus. These analyses utilize radar images collected at Arecibo Observatory in 1988 (spatial resolution 1 km). Changes in the radar brightness of lava flows with downslope distance from possible vents are inconsistent with trends observed for single terrestrial lava flows. This observation, coupled with evidence of multiple eruptive vents, suggests that most of the large flows in Western Eistla Regio are formed by coalescence of numerous smaller flows. There is also evidence for high-Fresnel reflectivity material at the summit of Gula Mons. Chapter 4 compares the radar polarization properties of volcanic deposits on Sif and Gula Montes to data for terrestrial lava flows and a smooth desert area. With the exception of units atop Gula Mons, flows in Eistla Regio probably exhibit a range of morphologies from smooth "pavements" to possible pahoehoe analogs.; Chapter 5 presents a study of lunar crater rays using high-resolution (30 m) radar images collected at Haystack Observatory, and focuses on the bright ray in Mare Serenitatis and ray segments attributed to Tycho and Copernicus craters. This study found that rays with high visible albedo are also characterized by high depolarized radar backscatter. The ray which passes west of Bessel crater was found to have a high nondiffuse depolarized echo, interpreted to indicate a furrowed or pitted terrain at spatial scales of only a few m. Photographs and radar images suggest that this ray was formed by the Menelaus impact event.