Magellan mission to Venus

The Magellan spacecraft arrived at Venus on August 10, 1990 to begin global high-resolution radar image and altimeter mapping and gravity field determination of the planet. Mapping of this cloud covered planet is done from an elliptical orbit with a 3.15 hour period and a 275 km periapsis. After the initial checkout of the spacecraft, the primary missions lasts for 243 days (one Venus day); the time it takes for Venus to make one revolution beneath the spacecraft. The data collected by Magellan is expected to provide an understanding of the geological and geophysical nature of the planet Venus, and the general processes that control planetary evolution.