This image of Tyrrhena Patera is a mosaic of daytime thermal infrared images colorized with a mosaic of nighttime temperature images (purple/blue is coldest, yellow/red is warmest).

The colder nighttime temperatures (blue hues) in the caldera and on the flanks of the volcano indicate that this area is likely covered with finer-grained materals. This contrasts strongly against the warm (red) area to the northwest. These warmer temperatures indicate a rockier surface, possibly even exposed bedrock. This is especially probably where the red hues conform with the topography.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.