Deathbed Revelations; January 1995; Scientific American Magazine; by Powell; 1 Page(s)

The Magellan spacecraft, which produced spectacular radar images of the surface of Venus, gave its life to science when it plunged into that planet¿s murky atmosphere on October 12. Project scientists had maneuvered Magellan into a low, and ultimately sacrificial, orbit so that it could map Venus¿s gravitational field. Tiny wiggles in the orbit betrayed local variations in the mass of the planet, clues to its internal structure. The resulting gravity map is shown here superimposed on an exaggerated-relief image of Venus¿s topography. Gravitational highs are rendered in red; gravitational lows are displayed in blue.

As Magellan dipped closer to its infernal doom, it performed unprecedented acrobatic feats. The drag created as the craft sped through the thin upper atmosphere pulled it ever downward, producing the first real-world test of aerobraking. The new fuel-saving technique will be used by the Mars Global Surveyor to help guide it into orbit around the red planet in 1997.