NASA's Galileo Jupiter orbiter flew to within 138km (75nm) of Jupiter's moon, Callisto, on 25 May, marking the closest fly-by of any Jovian moon. The craft's camera appeared to function well after malfunctioning as Galileo encountered intense radiation in preparation for the close approach.
Galileo will fly three more close approaches - to sulphurous volcanic moon Io and the tiny moon Amalthea - before being commanded to plunge into Jupiter's atmosphere in September 2003 on its 35th orbit of the planet since December 1995.
Source: Flight International