Hampered by a communications antenna that never unfurled, the Galileo spacecraft became known as the plucky mission that overcame major obstacles. During more than 6 years of touring Jupiter and its four largest moons, the spacecraft managed to radio some 5 gigabytes of data to Earth, including more than 14,000 images. It has recorded towering volcanic plumes above Jupiter's moon Io, gathered evidence that Europa might have an ocean beneath its icy carapace, and investigated the intense radiation environment near Jupiter.
Now, 13 years after its launch, the mission is winding down. During several flybys of Io, Galileo has received nearly 4 times the radiation dose it was designed to endure. On Jan. 17, a half-hour before the craft took its last swing past Io's rarely glimpsed Jupiter-facing side, radiati