Saturday, July 31, 2010

Dust Fans on the Seasonal Carbon Dioxide Polar Cap

During the long dark night of Martian winter at the South Pole, carbon dioxide in its solid form (also known as "dry ice") accumulates and forms a seasonal polar cap.

As the Sun comes up in the spring, the ice evaporates in a complex way. This observation shows dark dust being blown across the seasonal south polar cap. The dust comes from the surface beneath the ice: it either starts at spots bare of ice, or it's possible that it's lofted from below the ice in geyser-like plumes.

Local winds blow the dust from its source, forming a long fan. When the wind changes direction, a new fan is formed pointing in the new direction In this single image we can see that the wind has blown in a number of directions. This data will be used to study weather patterns near the South Pole.

Photo credit: NASA/JPL/University of Arizona

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