I.

Introduction

Galileo (spacecraft), American unmanned spacecraft designed to orbit Jupiter and send a probe into its atmosphere. Launched on October 18, 1989, from the space shuttle Atlantis, the Galileo orbiter followed a circuitous route before reaching Jupiter in 1995. It then moved into orbit around the planet and began monitoring and photographing Jupiter’s turbulent atmosphere, four largest moons, and surrounding magnetosphere. An atmospheric probe was released from the orbiter and dropped into the Jovian clouds on December 7, 1995, to take chemical and physical measurements of this heretofore unseen environment.

Originally scheduled to launch in 1986 on a more direct, two-year flight to Jupiter, the Challenger shuttle explosion forced the National Aeronautics and Space Administration (NASA) to revise plans and budgets for the mission. NASA engineers instead devised a looping six-year journey in which Galileo would dip into the gravitational fields of Venus and Earth to pick up enough velocity to reach Jupiter. This 38-month Venus-Earth-Earth Gravity Assist ended with the second, and final, Earth flyby before arriving at Jupiter in 1995.