This telescopic view from orbit around Mars catches a Martian dust devil
in action in the planet's southern hemisphere. The swirling vortex of dust
can be seen near the center of the image. The shadow cast by this column
of dust can be seen in the upper left while the dark track left by the
passage of the dust devil is evident in the lower right.
This is a cutout from an image taken by the High Resolution Imaging
Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter
on June 15, 2009. The scene is at 68.6 degrees south latitude, 11.4
degrees east longitude.
Dust devils on Mars form the same way that they do on Earth. The ground
heats up during the daytime, warming the air immediately above the
surface. This hot layer of air rises and the cooler air above falls,
creating vertical convection cells. A horizontal gust of wind causes the
convection cells to rotate, resulting in a dust devil. As the dust devil
moves across the surface of Mars it can pick up and disturb loose dust,
leaving behind a track.
Full-frame images from this HiRISE observation, catalogued as
ESP_013545_1110, are at http://hirise.lpl.arizona.edu/ESP_013545_1110.
The image was taken at 3:07 p.m. local Mars time, with the sun 37 degrees
above the horizon. The season was summer in the southern hemisphere of
Mars.
NASA's Jet Propulsion Laboratory, a division of the California Institute
of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for
NASA's Science Mission Directorate, Washington. Lockheed Martin Space
Systems, Denver, is the prime contractor for the project and built the
spacecraft. The High Resolution Imaging Science Experiment is operated by
the University of Arizona, Tucson, and the instrument was built by Ball
Aerospace & Technologies Corp., Boulder, Colo.