NASA Mars Orbiter Catches Twister in Action
A towering dust devil casts a serpentine shadow over the Martian surface in a new image from the high-resolution camera on NASA's Mars Reconnaissance Orbiter.
An afternoon  whirlwind on Mars lofts a twisting column of dust more than half a mile (800  meters) high in an image from the High Resolution Imaging Science Experiment  (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.HiRISE  captured the image on Feb. 16, 2012, while the orbiter passed over the Amazonis  Planitia region of northern Mars. In the area observed, paths of many previous  whirlwinds, or dust devils, are visible as streaks on the dusty surface.The active  dust devil displays a delicate arc produced by a westerly breeze partway up its  height. The dust plume is about 30 yards or meters in diameter.The image was  taken during the time of Martian year when that planet is farthest from the sun.  Just as on Earth, winds on Mars are powered by solar heating. Exposure to the  sun's rays declines during this season, yet even now, dust devils act  relentlessly to clean the surface of freshly deposited dust, a little at a  time.Dust devils  occur on Earth as well as on Mars. They are spinning columns of air, made  visible by the dust they pull off the ground. Unlike a tornado, a dust devil  typically forms on a clear day when the ground is heated by the sun, warming  the air just above the ground. As heated air near the surface rises quickly  through a small pocket of cooler air above it, the air may begin to rotate, if  conditions are just right.The Mars  Reconnaissance Orbiter has been examining Mars with six science instruments  since 2006. Now in an extended mission, the orbiter continues to provide insights  into the planet's ancient environments and how processes such as wind, meteorite  impacts and seasonal frosts continue to affect the Martian surface today. This  mission has returned more data about Mars than all other orbital and surface  missions combined.More than 21,700  images taken by HiRISE are available for viewing on the instrument team's website:http://hirise.lpl.arizona.edu.  Each observation by this telescopic camera  covers several square miles, or square kilometers, and can reveal features as  small as a desk.HiRISE is operated  by the University of Arizona, Tucson. The instrument was built by Ball  Aerospace & Technologies Corp., Boulder, Colo. The Mars Reconnaissance  Orbiter Project and the Mars Exploration Rover Project are managed by the Jet  Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission  Directorate, Washington. JPL is a division of the California Institute of  Technology, also in Pasadena. Lockheed Martin Space Systems, Denver, built the  orbiter. For more about the Mars Reconnaissance Orbiter, seewww.nasa.gov/mro.