Status Report

Mars Odyssey THEMIS Image: Yardangs in Medusa Fossae

By SpaceRef Editor

July 29, 2002

Filed under Daily Themis Pictures, Mars Odyssey THEMIS, US

Image Context:

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

[ Find on map: Javascript version ]

[ Find on map: CGI version ]

This THEMIS visible image covers a portion of the Medusa Fossae formation,
near the equator of Mars. The most characteristic feature of the Medusa
Fossae formation is the abundance of “yardangs”, which are erosional landforms
carved by the wind. These features usually form in a linear fashion, and can
be indicators of prevailing paleowind directions. On Earth, yardangs are
typically found in rocks that are easily eroded, such as those that form from
consolidated volcanic ash, dust-fall deposits or lake sediments.

In this particular area of Medusa Fossae, the size, spacing, and orientation
of the yardangs varies throughout the image. The largest form a stripe across
the center of the image, while the smallest are found in the top half of the
image (look closely). The small yardangs at the very top of the image are
oriented NW-SE; however, the orientation changes to NE-SW near the bright
ridge in the center of the image. The variation in size and orientation
appears to correspond with topographic layers, and may be due either to
differences in consolidation or changes in wind strength or direction as the
yardangs were formed. Finally, the terrain in the lower third of the image
appears etched or pitted, and was probably also formed by wind erosion.

[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