There are many dust devils on Mars -- little twisters that raise dust from the surface. They have also cleaned dust off of the solar panels of the rovers Opportunity and Spirit, improving the solar power production. (Spirit became stuck in 2009 and ceased communication a year later.) HiRISE sees many dust-devil tracks on Mars, but rarely captures an active feature because the images cover such small areas and because the typical time of day near 3 p.m. is past the peak heating and dust-devil activity. The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 29.5 centimeters (11.6 inches) per pixel (with 1 x 1 binning) to 58.9 centimeters (23.2 inches) per pixel (with 2 x 2 binning)]. North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21457