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FOR IMMEDIATE RELEASE                                                May 29, 1991

       Magellan Project scientists today described the results of the first 243-day radar mapping cycle of Venus as the spacecraft continued in a second cycle of exploring the cloud-shrouded surface of our nearest planetary neighbor.

       The first mapping cycle, begun last Sept. 15, imaged 84 percent of the planet. The cycle ended May 15 and the second cycle, to map the remainder of the surface, began immediately.

       The spacecraft's orbit was trimmed on May 17 to enhance its altimetry coverage of Venus. The altimetry instrument measures the heights of features on the surface.

       Dr. Stephen Saunders, project scientist, gave a summary of science findings during the first cycle and compared radar images from the first two orbits last August when the radar instrument was being tested with new data covering the same surface area.

       Saunders and the other Magellan scientists addressed a news conference at NASA Headquarters in Washington, D.C.

       Saunders reviewed global features, emphasizing wind streaks, large features called coronas and the continent-sized upland, Aphrodite Terra.

       Dr. James Head of Brown University, a member of the science team, discussed volcanic features and global distribution of volcanoes, and described the search for surface changes during the second mapping cycle.

       Dr. Gordon Pettengill of Massachusetts Institute of Technology, principal investigator of the radar science group, released new altimetry and radiometry results with emphasis on western Aphrodite Terra, and the peculiar characteristics of festoon -- looped or curved -- lava flows.

       New radar images were released, along with a new video creating a simulated flight over a three-dimensional Venus surface. The tape shows a large area of distinctive impact craters and a closeup of strange volcanoes called "pancake domes."


5/29/91 JJD