Galileo takes the Amalthea plunge

Nearing the end of its fuel supply, NASA’s Galileo probe passes one of Jupiter’s innermost moons, tiny, asteroid-like Amalthea, at a distance of less than 100 miles, coming closer to Jupiter and its belts of intense radiation than ever before. This final flyby of a Jovian moon is a punishing one for Galileo: the failure of Galileo’s main antenna dish after its 1989 launch has forced the robotic explorer to store its findings on tape for later playback to Earth at a low bit rate, but in this case roughly half of Galileo’s measurements of the highly charged environment near Jupiter are lost to radiation-induced failure of the tape recording system. The intense radiation also causes enough faults in Galileo’s main computer that the probe puts itself in a failsafe mode and “sleeps” until further commands are received from Earth hours later.