NIMS Image of Io - Second Encounter Target Name:   Io Spacecraft:   Galileo Produced by:   NASA/JPL Copyright:  Public Domain Date Released:  1998-03-26

• Io

The Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft imaged Io at high spectral resolution at a range of 439,000 km (275,000 miles) during the second Ganymede encounter on 6 September 1996. This image shows, on the right, Io as seen by NIMS, centered on 220 W longitude. The image on the left shows the same view point from Voyager data (from the encounters in 1979 and 1980). The NIMS image can be compared to the above NIMS hotspot image (from the First orbit on June 1996) to monitor changes on Io. The most dramatic feature of this image is the hotspot at Malik Patera. Preliminary analysis of the data yields a temperature of at least 1000 K (727 C) for this hotspot, an increase of more than 300 K from the first encounter. In the overlap area of the first and second images all the hotspots seen during the first encounter are also seen in the second image. Other hotspots were seen, including one at the Pele plume origin site. This image is at the 4 micron band to best view the Malik hotspot. Most of the other hotspots are best seen at longer wavelengths. NIMS is continuing to observe Io to monitor volcanic activity throughout the Galileo mission.