The journey back to Mars begins with a liftoff of the Mars Global Surveyor atop a Delta II 7925A expendable launch vehicle from the Cape Canaveral Air Station. After an approximate 10-month interplanetary odyssey, the spacecraft will arrive at Mars and begin a 4-month aerobreaking phase, an irnovative technique first demonstrated during the Magellan mission to Venus, to achieve a mapping orbit. It will take about 2 Earth years for Surveyor to circle above most of the planet, its suite of sophisticated remote-sensing instruments building a comprehensive global portrait of Mars by mapping its topography, magnetism, mineral composition and atmosphere. Among the locations the Surveyor will pass over are the landing sites where the two U.S. Viking landers have stood since 1975 as silent monuments to the most recent successful U.S. missions to Mars. The Global Surveyor is the first of a trio of spacecraft being launched to Mars; next is Russia's Mars `96 spacecraft, followed by the U.S.'s Mars Pathfinder.