NASA Mars Odyssey THEMIS Image: Ares Valles: Night and Day

Image Context:


Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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This pair of images shows part of the Ares Valles region.

Day/Night Infrared Pairs

The image pairs presented focus on a single surface feature as seen

in both the daytime and nighttime by the infrared THEMIS camera.

The nighttime image (right) has been rotated 180 degrees to place north at

the top.

Infrared image interpretation

Daytime:

Infrared images taken during the daytime exhibit both the morphological and

thermophysical properties of the surface of Mars. Morphologic details are

visible due to the effect of sun-facing slopes receiving more energy than

antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope

appearance that mimics the light and shadows of a visible wavelength image.

Thermophysical properties are seen in that dust heats up more quickly than

rocks. Thus dusty areas are bright and rocky areas are dark.

Nighttime:

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.

[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