NASA Mars Odyssey THEMIS Image: Pinwheel Crater at Night

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Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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The Odyssey spacecraft has completed a full Mars year of observations

of the red planet. For the next several weeks the Image of the Day

will look back over this first mars year. It will focus on four

themes: 1) the poles – with the seasonal changes seen in the retreat

and expansion of the caps; 2) craters – with a variety of morphologies

relating to impact materials and later alteration, both infilling

and exhumation; 3) channels – the clues to liquid surface flow; and

4) volcanic flow features. While some images have helped answer

questions about the history of Mars, many have raised new questions

that are still being investigated as Odyssey continues collecting

data as it orbits Mars.

Infrared images taken during the nighttime exhibit only the thermophysical

properties of the surface of Mars. The effect of sun-facing versus non-sun-facing

energy dissipates quickly at night. Thermophysical effects dominate as different

surfaces cool at different rates through the nighttime hours. Rocks cool

slowly, and are therefore relatively bright at night (remember that rocks are

dark during the day). Dust and other fine grained materials cool very quickly

and are dark in nighttime infrared images.

This nighttime IR image was collected September 28, 2002 during the northern spring season. The “pinwheel” pattern represents alternating warm and cool materials.

[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