Magellan was the first planetary spacecraft to be launched from a space shuttle. It orbited Venus in a near polar, elliptical orbit, with a minimum altitude (periapsis) of 243 kilometers (150 miles). It made detailed maps of 98% of the planet's surface using synthetic aperture radar. Magellan revealed no evidence on Venus of plate tectonics, such as operates with such profound effect on Earth. Volcanoes have left their marks on 85% of Venus, with lava plains, lava domes, large shield volcanoes, and extremely long lava channels. The rest of the surface is covered with ranges of deformed mountains. Magellan also made detailed gravity maps of Venus, determining that the gravity field is highly correlated with surface topography.

The Magellan spacecraft was launched on May 4, 1989, arrived at Venus on August 10, 1990 and was inserted into a near-polar elliptical orbit with a periapsis altitude of 294 km at 9.5 deg. N. Radio contact with Magellan was lost on October 12, 1994. The primary objectives of the Magellan mission were to map the surface of Venus with a synthetic aperture radar (SAR) and to determine the topographic relief of the planet. At the completion of radar mapping 98% of the surface was imaged at resolutions better than 100 m, and many areas were imaged multiple times. The image at the top of the page shows the 30-km diametar crater Adivar, with a jet-like streak extending off to the left. The streak, which measures over 500 km in length, is probably the result of the initial crater-forming impact. (This image is from C1-MIDR 15N077;1, framelet 52, Magellan CD-ROM MG_0019.) The mission was divided up into "cycles", each cycle lasted 243 days (the time necessary for Venus to rotate once under the Magellan orbit - i.e. the time necessary for Magellan to "see" the entire surface once.) The mission proceeded as follows:

• 04 May 1989 - Launch
• 10 Aug 1990 - Venus orbit insertion and spacecraft checkout
• 15 Sep 1990 - Cycle 1: Radar mapping (left-looking)
• 15 May 1991 - Cycle 2: Radar mapping (right-looking)
• 15 Jan 1992 - Cycle 3: Radar mapping (left-looking)
• 14 Sep 1992 - Cycle 4: Gravity data acquisition
• 24 May 1993 - Aerobraking to circular orbit
• 03 Aug 1993 - Cycle 5: Gravity data acquisition
• 30 Aug 1994 - Windmill experiment
• 12 Oct 1994 - Termination experiment - loss of signal
• 13 Oct 1994 - Presumed loss of spacecraft

Email Article to a Friend