Hotspots on Io During the Ganymede 2 Encounter

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 G2 encounter on 6 September 1996. This image shows, on the right, Io as seen by NIMS, centered on 150 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 NIMS hotspot image from the G1 orbit (June 1996) to monitor changes on Io. The most dramatic feature of the G2 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 G1 encounter. In the overlap area of the G1 and G2 images all the hotspots seen during the G1 encounter are also seen in the G2 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.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.