NASA Mars Odyssey THEMIS Image: Ius Chasma In False Color

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Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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The Odyssey spacecraft has taken some great pictures of Valles Marineris, the largest canyon in the solar system. If this canyon were on Earth, it would stretch from New York to Los Angeles. For the next several weeks, the Image of the Day will tour some of the canyons that make up this vast system. We will start with Ius Chasma in the west, and end with Coprates Chasma to the east. For more information on Vallis Marineris, please see http://mars.jpl.nasa.gov/mep/science/vm.html.

This daytime false-color image was collected during the southern spring season.

The THEMIS VIS camera is capable of capturing color images of the Martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast-enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a single full-color image. Because the THEMIS color filters don’t span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast-enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

[Source: ASU THEMIS Science Team]

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.

Image Credit: NASA/JPL/Arizona State University