A close-up look at Io from Galileo's near-infrared mapping spectrometer

Infrared spectral images of Jupiter's volcanic moon lo, acquired during the October and November 1999 and February 2000 flybys of the Galileo spacecra ft, were used to study the thermal structure and sulfur dioxide distributio n of active volcanoes. Loki Patera, the solar system's most powerful known volcano, exhibits Large expanses of dark, cooling lava on its caldera floor . Prometheus, the site of long-lived plume activity, has two major areas of thermal emission, which support ideas of plume migration. Sulfur dioxide d eposits were mapped at local scales and show a more complex relationship to surface colors than previously thought, indicating the presence of other s ulfur compounds.