Dust Devils on Mars

While it's not as glamorous as chasing tornadoes, chasing dust devils can be lots of fun. It's also possible to collect data about wind speed and pressure inside a dust devil if you can find a place where they track along a line. All that's required is to drive ahead of the expected track and wait for the whirlwind to arrive. Video and sequential still photography of more distant dust devils can yield wind speed without subjecting an expensive camera to fast-moving dust particles.

It's long been known that dust devils occur on Mars. Their tracks in the sand give them away. Now NASA has captured ground images of Martian whirlwinds like the one shown here. The raw images, which were taken at 20-second intervals, show only faint outlines of a dust devil. Image experts significant enhanced the contrast of the images by blocking everything in a sequence of photos that didn't move. The result is an image that clearly shows a dust devil. A string of several images can be assembled into an animated GIF that shows a dust devil whipping across a Martian desert. To see the animated versions, see Movie Clip Shows Whirlwinds Carrying Dust on Mars and Dust devil on Mars, seen by Spirit (both 21 April 2005).

Forrest M. Mims III