Magellan: Electrical and Physical Properties of Venus' Surface

Magellan probes Venus' surface by 12.6-cm-wavelength vertical and oblique radar scattering and measures microwave thermal emission. Emissivity and root-mean-square slope maps between 330° and 30°E and 90°N and 80°S are dissimilar, although some local features are exceptions. Inferred surface emissivities typically are ∼0.85, but vary from ∼0.35 at Maxwell to ∼0.95 northeast of Gula Mons and other locations. Lowest emissivities appear in topographically high areas; this relation suggests that a phase change or differences in chemical weathering occur at about 6055-kilometer radius. Initial results indicate that there are significant variations in the surface scattering function.