Status Report

NASA Mars Odyssey THEMIS Image: Arsia Mons by Day and Night

By SpaceRef Editor
June 22, 2004
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Medium image for 20040622A

Image Context:

Context image for 20040622A
Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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ParameterValue ParameterValue
Latitude-19.6 &nbsp InstrumentIR
Longitude241.9E (118.1W) &nbsp Resolution (m)100
Image Size (pixels)1149×320 &nbsp Image Size (km)114.9×32

This image is part of the following themes:

Full data on this image has now been released via the THEMIS Data Releases website.

This pair of images shows part of Arsia Mons.

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

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.

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]

Note: this THEMIS infrared 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.

Image Credit: NASA/JPL/Arizona State University

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