Status Report

Mars Odyssey THEMIS Image: Reull Vallis Source Region

By SpaceRef Editor
July 1, 2002
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Medium image for 20020701a

Image Context:
Context image for 20020701a
Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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The jumbled, chaotic terrain in this THEMIS image may represent a source region for the Reull Vallis, one of the larger channel systems in the southern hemisphere of Mars. Such regions of chaos are thought to form by the catastrophic release of groundwater. If this was the case, then the water would have flowed down gradient to the south and may have contributed to the formation of the Reull Vallis. The top of the image shows two short segments of channels that are interrupted by the chaos, demonstrating that there was a channel system in place before the ground foundered to produce the chaos. One of the more intriguing features seen among the jumbled blocks are narrow ledges that vaguely resemble bath tub rings in the way they conform to the topography. Two good examples are seen running roughly left-right across the image about a fourth of the way down. At first they appear to be layers protruding from the cliff faces, but upon closer inspection a more ledge-like character is evident. Note how they appear different between the south-facing and north facing cliffs. The occurrence of one of these features on the south-facing interior rim of the largest crater in the image but nowhere else around the rim argues against the idea that the ledges are due to a layer of rock cropping out throughout the landscape. Instead, they appear more like the edges of a layer of sediment that drapes the topography. It is possible that the sediment is mixed with ice and is best preserved in the shadowed portions of the terrain. There is no easy explanation for these unusual features. They represent one more Martian enigma.

[Source: ASU THEMIS Science Team]

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.

Image Credit: NASA/JPL/Arizona State University

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Value ParameterValue
Latitude-32.7 &nbsp InstrumentVIS
Longitude247W (113E) &nbsp Resolution (m)19
Image Size (pixels)3061×1203 &nbsp Image Size (km)58.2×22.9

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