Io as a source of the jovian dust streams

Streams of dust emerging from the direction of Jupiter were discovered in 1 992 during the flyby of the Ulysses spacecraft(1,2), but their precise orig in within the jovian system remained unclear(2). Further data(3-5) collecte d by the Galileo spacecraft, which has been orbiting Jupiter since December 1995, identified the possible sources of dust as Jupiter's main ring(6), i ts gossamer ring(7), comet Shoemaker-Levy 9 (ref. 8) and Io. All but Jupite r's gossamer ring and Io have since been ruled out(4,9-14). Here we find th at the dominant source of the jovian dust streams is Io, on the basis of pe riodicities in the dust impact signal. Io's volcanoes, rather than impact e jecta, are the dust sources.