NASA/JPL/Malin Space Science Systems
Mars was once a much wetter world than it is today. Locked within the martian bedrock are ancient channels and valleys through which liquids---e.g., water---once flowed. In the Aeolis region of Mars, wind erosion has exposed and inverted a plethora of ancient channels---stream beds---in a fan-shaped sedimentary rock unit near 6.3°S, 208.6°W. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The smooth-looking, sinuous ridges that run left-right across the image are the inverted channels. The rugged, sharp-looking ridges that run nearly north-south (up-down) through the image are yardangs--ridges formed by wind erosion. The water (or other liquid) responsible for the original channels flowed from the left (west) to right/upper right (east/northeast). This scene covers an area approximately 3 km (1.9 mi) across, and is illuminated by sunlight from the upper left.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, California. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California and Denver, Colorado.