The Magellan Venus Radar Mapping Mission

The NASA Magellan Venus Radar Mapper spacecraft was launched into an interplanetary transfer trajectory to Venus on May 4, 1989, and will be placed into orbit around Venus on August 10, 1990. The orbiter carries a 12-cm-wavelength, multimode radar system. In the synthetic aperture mode it is capable of imaging most of the Venus surface at a resolution of better than 300 m, approaching 120 m over more than half the planet. In the altimeter mode it will determine topographic relief to a vertical accuracy of better than 50 m averaged over a surface resolution cell approximately 10 km in diameter where the surface relief is not too extreme. In the radiometer mode the radar receiver can determine the surface radio emission brightness temperature with an absolute accuracy of 20 K, at a resolution of 2 K. Tracking of the orbiter's coherent radio telemetry transmitter will permit observations of small accelerations related to gravitational inhomogeneities in the planet's interior. Objectives of the mission include deducing the geological history of the surface and the geophysical state of the interior. Specific attention focuses on the origin, present distribution, and activity of four geological processes that modify the surface: (1) volcanic and tectonic; (2) impact; (3) erosional, depositional, and chemical; and (4) isostatic and convective. Data products resulting from the mission will be made available to members of the scientific community through NASA's Planetary Data System.