 Complete the following phrase:  Planning for the next NASA mission to Jupiter began in 1977, just as the two Voyager probes were launched. Rather than performing a flyby of the Jupiter system like all the missions preceding it, the Galileo spacecraft would orbit Jupiter to perform close-up observations of the planet and its many moons, including Io, as well as deliver a Jovian atmospheric probe. Originally scheduled to be launched via the Space Shuttle in 1982, delays resulting from development issues with the shuttle and upper-stage motor pushed the launch back, and in 1986 the Challenger 