Searching for Surficial Deposits on Venus Using Multi-polarization Radar

Introduction. The Magellan spacecraft returned hundreds of images of craters, radar-dark halos, and wind features on Venus. It is clear that surficial layers are associated with some of these features; for example, 59 of the craters have parabolic shaped deposits that are thought to be a few centimeters to a meter in thickness [1],[2]. Magellan also revealed about 400 radar dark “splotches” that may be places where a smooth rubble layer was formed when the shock wave from an impactor hit the surface and crushed the rock [3]. Two dune fields and several areas of microdunes were identified in Magellan data, as well a few thousand windstreaks, so it is clear that dust is transported and re-deposited by wind. [4]. Thin surficial layers that are not clearly visible in the Magellan imagery may be present in other regions as well. In fact, many surfaces on Venus that were imaged by Magellan SAR may look much different when viewed at optical wavelengths, since radar waves penetrate surface layers and show details of the underlying terrain. A good example is the L-Band (24 cm wavelength) shuttle imaging radar (SIR-A) observations by McKauley et al. [5] who detected buried river valleys in the Arbain Desert in southern Egypt.