Spring Fans at Macclesfield
Every Martian spring, fans of dust are blown out from under the seasonal layer of carbon dioxide ice that forms a polar cap over the winter.
Gas blowing out from under the ice carries with it a load of dust that is deposited on the surface in a direction determined by the wind at the time of the eruption. Like windsocks, these fans in a polar area we've dubbed Macclesfield, record the direction that the wind was blowing.
A citizen science task at Planet Four enlists the public to outline the fans. Their measurements go into a data base that will ultimately help us to understand weather on Mars.
The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. (The original image scale is 49.1 centimeters [19.3 inches] per pixel [with 2 x 2 binning]; objects on the order of 147 centimeters [57.9 inches] across are resolved.) North is up.
The University of Arizona, in Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.