A model for the formation of the extended paraboloidal halos around some impact craters on Venus

Many parabolic-shaped extended impact crater-related features have been found in Magellan synthetic aperture radar and emissivity data covering much of the surface of Venus. They are oriented east-west with the apex to the east and the impact crater located just west of the apex. A model for the formation of the parabolic features is developed based on the injection of small particles into the upper atmosphere at the time of impact, and their subsequent transport to the west by the east-west zonal winds. Fallout times from 50 km in the Venus atmosphere for particles of this size are about two hours, allowing westerly drifts of several hundred kilometers for zonal winds of 50 to 100 m s(exp -1).