Image of Magellan orbiting Venus.
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NASA/JPL
Magellan
On May 4, 1989, Magellan, a spacecraft built mostly from spare parts from other missions, was carried into Earth orbit by the Atlantis space shuttle and launched toward Venus. It arrived on Aug. 10, 1990 and inserted itself into a highly elliptical polarorbit.
Over the next 3 years, Magellan used radar to penetrate the dense cloud cover surrounding Venus and map its surface. With every orbit it sent back strips of data, which were assimilated by scientists back on Earth into a 98% complete global map. Because Magellan viewed the Venusian surface from varying angles, 3-dimensional images of the planet's terrain were also possible.
After studying Venus' gravitational field for a year, Magellan then plunged into its atmosphere, testing a new technique for controlling surface descent, called aerobraking. Aerobraking involves dipping a spacecraft's orbit through a planet's atmosphere, thus creating friction which slows it down and results in a more energy-efficient descent. Although Magellan was crushed by the Venus' pressure before reaching the surface, scientists obtained valuable information that would make aerobraking useful in future missions.
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