May 20, 2009--Dark splotches on Martian dunes show where carbon-dioxide frost is sublimating--or turning directly from a solid to a gas--in this newly released image from NASA's HiRISE camera.

The high-resolution camera, carried aboard the Mars Reconnaissance Orbiter, can see features on Mars that are as small as 4 to 8 feet (1.2 to 2.4 meters) across, or about the size of the average dinner table. Previous missions could only discern objects at least as long as school bus (about 37 feet, or 11.3 meters).