Characterizing landing site safety on Venus using Venera panoramas and Magellan radar properties

Abstract This study explores an approach for identifying and characterizing sites on Venus where a future lander mission could attain a high probability of safe landing through a synthesis of Venera surface panoramas, Magellan radar properties, and existing global geological maps of the Venus surface. Surface panoramas from the Venera 9 and Venera 13 landers were used to define rock size distributions and to calculate the probability of a hazardous rock encounter for a reference Venus lander design at these specific landing sites. This surface analysis formed the basis and rationale for the development of a set of global filters seeking to identify “safe” 150-km-diameter landing ellipses with Magellan radiophysical properties including root mean square slope, radar backscatter coefficient, and emissivity values similar to the most benign regional plains unit (rp2) mapped by Ivanov and Head [2011] within the Venera 13 landing site. Using this method, 178 unique ellipses for which >95% of pixels exhibited rms slope and radar backscatter coefficient values similar to the Venera 13 rp2 unit were identified across the Venus surface. Of these ellipses, 36 also contained >95% of pixels with similar emissivity values as the Venera 13 rp2 unit. “Safe” ellipses identified by this method were predominantly composed of regional plains, shield plains, and smooth plains as defined in the Venus global geologic map of Ivanov and Head [2011]. Although the method developed in this study for identifying and characterizing safe landing sites on Venus requires several assumptions regarding the correlation of orbiter radar data to surface properties relevant to lander safety, this approach provides a best effort starting point integrating available data for the systematic, relatively objective, and automatic identification of safe landing sites on Venus.