Magellen Spacecraft Arrives at Venus

The Magellan spacecraft, also referred to as the Venus Radar Mapper, was a 1,035-kilogram robotic space probe launched by NASA on May 4, 1989, to map the surface of Venus using Synthetic Aperture Radar and measure the planetary gravity.

It was the first interplanetary mission to be launched from the Space Shuttle, the first to use an inertial upper stage booster and was the first spacecraft to test aerobraking as a method for circularizing an orbit. Magellan was the fourth successful, NASA funded mission to Venus and ended an eleven year U.S. interplanetary exploration hiatus.

Magellan was launched on May 4, 1989, at 18:46:59 UTC by the National Aeronautics and Space Administration from KSC Launch Complex 39B at the Kennedy Space Center in Florida, aboard Space Shuttle Atlantis during mission STS-30. Once in orbit, an Inertial Upper Stage booster, deployed from the shuttle and launched on May 5, 1989 01:06:00 UTC, sending the spacecraft into a Type IV, heliocentric orbit where it would circle the Sun 1.5 times, before reaching Venus 15 months later on August 10, 1990.

Originally, Magellan had been scheduled for launch in 1988 with a trajectory lasting six months. However, due to the Space Shuttle Challenger disaster in 1986, several missions, including Galileo and Magellan, were deferred until the shuttle flights resumed September 1988. Intended to be launched with a new, liquid fueled, Centaur-G shuttle deploy-able upper-stage booster, subsequently canceled after the Challenger disaster, Magellan had to be modified to attach to a less powerful solid-fueled, Inertial Upper Stage. The next best opportunity for launch would occur in October 1989.

Further complicating the launch however, was the upcoming Galileo mission to Jupiter, which included a flyby of Venus. Intended for launch in 1986, the pressures to ensure a launch for Galileo in 1989, mixed with a short launch-window necessitating a mid-October launch, resulted in replanning the Magellan mission. Weary of rapid shuttle launches, the decision was made to launch Magellan in May, and into an orbit that would require 1 year and 3 months before encountering Venus.

Magellan was a unique mission, the first dedicated U.S. mission to study in detail, using Synthetic Aperture Radar (SAR), the surface of Venus. Because Magellan was intended to be a low cost mission, major components of the spacecraft were obtained from flight spares from other programs including Galileo, Viking, Voyager, Mariner, Skylab, Ulysses, and even the shuttle. Designed as a follow-up to the mapping portion of the Pioneer Venus mission, Magellan's purpose was to: (1) obtain near-global radar images of Venus' surface with a resolution equivalent to optical imaging of 1 km per line pair; (2) obtain a near-global topographic map with 50 km spatial and 100 m vertical resolution; (3) obtain near-global gravity field data with 700 km resolution and 2--3 milligals (1 gal = 1 cm/s**2) accuracy; and, (4) develop an understanding of the geological structure of the planet, including its density distribution and dynamics.