Magellan

A US orbiting probe of Venus, launched from the Space Shuttle Atlantis on 4 May 1989. Its objective was to map by means of synthetic aperture radar at least 70 per cent of the surface of Venus to a resolution of several hundred metres. The radar technique is essential since Venus is perpetually covered by opaque cloud. Magellan arrived at Venus on 10 August 1990 and its first phase of operation, over a period of 243 days, was successfully completed in May 1991, 84 per cent of the surface having been mapped. The next phase of observation involved filling in gaps and making more detailed observations. Previous studies had shown that volcanic lava flows cover about 80 per cent of Venus. The Magellan images have made it possible to examine these features in much closer detail. A number of large shield volcanoes have been identified, along with impact craters, one of the largest of which is 275 kilometres (170 miles) in diameter, together with a variety of features unique to Venus. The wealth of data returned by Magellan makes a very significant addition to our knowledge of the surface of Venus.