A Dust Devil Swirling on Mars . ... Credit Copyright: Mars Exploration Rover Mission , JPL , NASA Explanation: What is that wisp on the horizon? Scientists think that the slight white apparition is actually a Martian dust devil that was caught swirling across Mars . The above image was taken earlier this month by the robotic rover Spirit . ... Fresh dust devil tracks have been seen on Mars before, but actually seeing one up close was a surprise. ... NASA Official: Jay Norris. ...