The Surface Stereo Imager on NASA's Phoenix Mars Lander caught this dust
devil in action west-southwest of the lander at 11:16 a.m. local Mars time
on Sol 104, or the 104th Martian day of the mission, Sept. 9, 2008.
Dust devils have not been detected in any Phoenix images from earlier in
the mission, but at least six were observed in a dozen images taken on Sol
104.
Dust devils are whirlwinds that often occur when the Sun heats the surface
of Mars, or some areas on Earth. The warmed surface heats the layer of
atmosphere closest to it, and the warm air rises in a whirling motion,
stirring dust up from the surface like a miniature tornado.
The dust devil visible in the center of this image just below the horizon
is estimated to be about 400 meters (about 1,300 feet) from Phoenix, and 4
meters (13 feet) in diameter. It is much smaller than dust devils that
have been observed by NASA's Mars Exploration Rover Spirit much closer to
the equator. It is closer in size to dust devils seen from orbit in the
Phoenix landing region, though still smaller than those.
The image has been enhanced to make the dust devil easier to see.
The Phoenix Mission is led by the University of Arizona, Tucson, on behalf
of NASA. Project management of the mission is by NASA's Jet Propulsion
Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin
Space Systems, Denver.
