Mars Reconnaissance Orbiter Catches a Dust Devil on Mars (Forwarded)

University Communications
University of Arizona
Tucson, Arizona

Contact Information:
Yisrael Espinoza, 520-626-7432

July 20, 2007

HiRISE Catches a Dust Devil on Mars
By Lori Stiles

The University of Arizona-based High Resolution Imaging Experiment (HiRISE)
group this week released a good look at a dust devil on Mars. This is not
the storm bedeviling NASA's Mars Exploration Rovers, Spirit and Opportunity.

The HiRISE camera captured the dust twister by chance in its photographic
swath of a region in the southern hemisphere near Hellas Planitia during a
Martian mid-afternoon early last month. The HiRISE camera is orbiting the
Red Planet on NASA's Mars Reconnaissance Orbiter.

The HiRISE image is of a region east of the Hellas impact basin and south of
Reull Vallis. Details on this and other new images are posted on the HiRISE
website,
http://hirise.lpl.arizona.edu

Dust devils form when the temperature of the atmosphere near the ground is
much warmer than that above. The hot air rises, and under ideal conditions,
forms a vortex that sucks in more warm air. If the vortex is strong enough,
it will raise dust off the surface, forming a dust devil.

Dust devils generally form in the afternoon because the sunlight needs
sufficient time to warm the surface. Local time when this picture was taken
was 3:08 p.m.

The bright material is the dust within the vortex. A dark shadow cast by the
dust devil is visible to the right. This dust devil is about 200 meters
across (about 660 feet), but probably much smaller than that where it
touches the surface. Scientists estimate from the length of its shadow that
the dust devil is about 500 meters tall (about 1,600 feet).

The HiRISE camera takes images of 3.5-mile-wide (6 km) swaths as the orbiter
flies at about 7,800 mph between 155 and 196 miles (250 to 316 km) above
Mars' surface.

Professor Alfred McEwen of UA's Lunar and Planetary Laboratory is principal
investigator for HiRISE.

Information about the Mars Reconnaissance Orbiter is online at
http://www.nasa.gov/mro
The mission is managed by NASA's Jet Propulsion Laboratory, a division of
the California Institute of Technology, Pasadena, for the NASA Science
Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is
the prime contractor and built the spacecraft. The High Resolution Imaging
Science Experiment is operated by the University of Arizona. Ball Aerospace
and Technologies Corp., Boulder, Colo., built the HiRISE instrument.

Related Web sites:

* http://hirise.lpl.arizona.edu
* http://www.nasa.gov/mro