Status Report

Mars Odyssey THEMIS Image: Ares Vallis Polygons

By SpaceRef Editor

August 28, 2002

Filed under Daily Themis Pictures, Mars Odyssey THEMIS, US

Image Context:

Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team

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This jumble of eroded ridges and mesas occurs within Ares Vallis, one of
the largest catastrophic outflow channels on the planet. Floods raged
through this channel, portions of which are up to 25 km wide, pouring
out into the Chryse Basin to the north. Close inspection of the THEMIS
image reveals polygonal shapes on the floor of the channel system.
Polygonal terrain on Mars is fairly common although the variety of forms
and scales of the polygons suggests multiple modes of origin. Those in
Ares Vallis resemble giant desiccation polygons that form in soils on
Earth when a moist layer at depth drys out. While polygons can form
in icy soils (permafrost) and even lava flows, their presence in a
channel thought to have been carved by flowing water is at least
consistent with a mode of origin that involved liquid water.

[Questions? Email images@themis.asu.edu]

[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