Yardangs in Arsinoes Chaos, Mars

This view of Martian surface features shaped by effects of winds was captured by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter on Jan. 4, 2015. The spacecraft has been orbiting Mars since March 2006. On Feb. 7, 2015, it completed its 40,000th orbit around Mars. Several terrain types converge in this scene from the Arsinoes Chaos region of Mars, which is in the far eastern portion of Mars' Valles Marineris canyon system. The jumbled chaos terrain is likely related to massive water-carved outflow channels that started in this area and flowed north onto Mars' northern plains. The slightly curving bright terrain is composed of yardangs. Yardangs are portions of rock that have been sandblasted into long, skinny ridges by saltating (or bouncing) sand particles blowing in the wind. Transverse sand ridges lie between the yardangs (zoom in). These sand ridges are termed "transverse aeolian ridges" and are not moving in Mars' current climate. They are a mystery -- midway in height between dunes (formed from saltating sand) and ripples (formed by "splashed" sand grains). The location is at 7 degrees south latitude, 332 degrees east latitude. The image is an excerpt from HiRISE observation ESP_039563_1730. http://photojournal.jpl.nasa.gov/catalog/PIA19291