Venus: mapping the surface reflectivity by radar interferometry.

The surface reflectivity of Venus obtained by radar interferometry at a wavelength of 3.8 centimeters has been mapped for a region extending approximately from -80 degrees to 0 degrees in longitude (Carpenter's definition) and from -50 degrees to +40 degrees in latitude. The map is free from the twofold range-Doppler ambiguity because the interferometer fringe pattern makes possible the separation of two points of equal range and Doppler shift. The map presents many new features and clearly delineates features already observed. Most notably, the map shows large circular regions of significantly lower reflectivity than their surroundinigs.