Marching Dust Devils
Marching Dust Devils
ESP_042201_1715  Science Theme: Seasonal Processes
On an early fall (2015) afternoon in Ganges Chasma (Valles Marineris), we managed to capture a cluster of 8 dust devils, five of them in the enhanced color strip. They’re together on a dark sandy surface that tilts slightly to the north, towards the Sun.

Both of these factors help warm the surface and generate convection in the air above. The surface is streaked with the faint tracks of earlier dust devils. A pair of dust devils appears together at top right, spaced only 250 meters apart. These two have quite different morphologies. The bigger one (on the right) is about 100 meters in diameter and is shaped like a doughnut with a hole in the middle. Its smaller companion is more compact and plume-like, but it too has a small hole in the center, where the air pressure is lowest. It may be that the smaller dust devil is younger than the larger one. A row of four dust devils are in the middle of the color strip, separated by about 900 meters from one another.

This image might answer some interesting questions about the behavior of dust devils. Dust devils are theoretically expected to migrate uphill on a sloping surface, or migrate downwind when there is a breeze. Where they are found close together in pairs, they are expected to rotate in opposite directions. HiRISE color observations can be used to determine the direction of rotation and—for fast moving dust devils—the direction of their travel. This is because the different color observations (infrared, red, and blue) are taken at slightly different times. The differences between the earliest color observation and the last tell us about the changes that took place during that time interval.

All this requires careful analysis, but if these dust devils are moving fast enough, and spaced closely enough, these here might display some interesting “social dynamics,” possibly marching together and rotating in alternating directions.

Written by: Paul Geissler (narration: Tre Gibbs)  (4 November 2015)

This is a stereo pair with ESP_043190_1715.
Acquisition date
28 July 2015

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
267.3 km (166.1 miles)

Original image scale range
53.6 cm/pixel (with 2 x 2 binning) so objects ~161 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
43°, with the Sun about 47° above the horizon

Solar longitude
19.5°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  27.9°
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All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:

NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.