HOT-SPOTS ON IO - INITIAL RESULTS FROM GALILEOS NEAR-INFRARED MAPPINGSPECTROMETER

The Near-Infrared Mapping Spectrometer on Galileo has monitored the vo lcanic activity on Io since June 28, 1996. This paper presents prelimi nary analysis of NIMS thermal data for the first four orbits of the Ga lileo mission. NIMS has detected 18 new hot spots and 12 others which were previously known to be active. The distribution of the hot spots on Io's surface may not be random, as hot spots surround the two brigh t, SO2-rich regions of Bosphorus Regio and Colchis Regio. Most hot spo ts seem to be persistently active from orbit to orbit and 10 of those detected were active in 1979 during the Voyager encounters. We report the distribution of hot spot temperatures and find that they are consi stent with silicate volcanism.