Rocky Terrain Dust Storms Sand Dunes Return to Water Features index. It shows a thin coating of water ice on the rocks and soil. Then it remained on the surface for about 100 days.
Scientists believe dust particles in the atmosphere pick up bits of solid water.
That combination is not heavy enough to settle to the ground. But carbon dioxide, which makes up 95 percent of the Martian atmosphere, freezes and adheres to the particles and they become heavy enough to sink. Warmed by the Sun, the surface evaporates the carbon dioxide and returns it to the atmosphere, leaving behind the water and dust. The ice seen in this picture, like that which formed one Martian year ago, is extremely thin, perhaps no more than one-thousandth of an inch thick.