File:PIA00844 NIMS spectra.gif

English: The Near Infrared Mapping Spectrometer (NIMS) acquired this global mosaic (right) at a spatial resolution of 100 km during Galileo's third orbit on November 4, 1996, roughly 7.5 hours prior to Callisto closest approach.

The lighter bluish area in the upper latitudes is the Asgard multi-ring structure (the second largest surface feature on Callisto) with crater Burr to the north and Tornasuk to the east. The bluish color indicates regions with more exposed water ice while the reddish/rusty color indicates surface areas rich in non-ice minerals.

Compare the two spectra:

The Asgard spectrum shows a higher abundance of ice between 1 and 2 microns.

The dark terrain spectrum shows more "rocky" material and less ice.

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

The original NASA figure has been modified by inverting white and black, tripling the linear dimensions of the dots in the dark terrain spectrum, coloring these dots red, coloring the Asgard spectrum line blue, increasing the linear pixel density of the image by a factor of 4, and changing the text and numerals to a larger size (Arial) font.