NASA/JPL/Malin Space Science Systems
Yardangs are ridges formed by wind erosion. Most commonly, they will form in sedimentary rocks or volcanic ash deposits containing some amount of sand-sized grains (particles of 0.0625 to 2.0 millimeters size, like the grains in common table salt). This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of yardangs in the Memnonia Sulci region. The scene is located near 9.3°S, 172.4°W, and covers an area about 3 km (1.9 mi) wide. The ridges are 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.