Magellan (Venus Radar Mapper) spacecraft
Mosaic of Venus
Volcano on Venus
Magellan (Venus Radar Mapper) spacecraft

Magellan (Venus Radar Mapper) spacecraft

Courtesy of NASA

http://www2.jpl.nasa.gov/magellan/



Overview
Because this mission would make the first detailed maps of the entire surface of Venus, it was named after the 16th century Portuguese explorer, Ferdinand Magellan, who circumnavigated and mapped Earth. Venus’ dense and opaque atmosphere meant that normal optical cameras wouldn’t work for imaging—instead, Magellan used bursts of microwave energy that passed through the clouds and illuminated the planet's surface. The radar system measured the brightness of each pulse as it reflected back, and then that data was used to map the planet, strip by strip as it rotated. Magellan was the first spacecraft to be launched from a space shuttle.


Launch
May 4, 1989


Arrival
August 10, 1990


End of Mission
October 13, 1994


Goals
Make the most detailed radar images of Venus, map the surface topography, and the electrical characteristics. Use precision radio tracking to measure Venus’ gravitational field and show the planet’s internal mass distribution.


Findings
Magellan collected radar images of 98% of the planet’s surface and measured the surface topography and electrical characteristics. It provided evidence to understand the role of impacts, volcanism, and tectonics in the formation of surface structures on Venus. Magellan helped us see that Venus’ surface is covered by volcanic materials and features (lava plains, small lava domes, and large-shield volcanoes). There are few impact craters, suggesting that the surface is geologically young, less than 800 million years old. Magellan found lava channels over 6000 km long providing evidence for river-like flows of lava that probably erupted at a high rate. What Magellan did not find were typical signs of terrestrial plate tectonics, continental drift, and basin floor spreading. Instead, the tectonics features found were global rift zones and numerous broad, low dome structures called coronae. Coronae are formed by the upwelling and settling of magma from the mantle. Although Venus has a dense atmosphere, there is no data to support wind erosion. This is different from Mars, where there is a thin atmosphere, but good evidence for wind erosion of dust and sand.