No abstract

Previous studies of NASA's Magellan radar data showed that most of the Venus highlands exhibit a single reduction in radar emissivity values at high altitudes, above 6,053 km (Klose et al., 1992; Pettengill et al., 1992). This decline in radar emissivity with altitude is ascribed to the presence of minerals with a high dielectric constant produced by chemical weathering reactions between the rocks and the near-surface atmosphere. It is expected from theory that materials with high dielectric constants will enhance their radar reflectivity and lower their radar emissivity (Campbell, 1994; Pettengill et al., 1992). Proposed minerals include: (1) pyrite produced through sulfidation and/or oxidation of iron (