Dust Fans on the Seasonal Carbon Dioxide Polar Cap
Dust Fans on the Seasonal Carbon Dioxide Polar Cap
PSP_003180_0945  Science Theme: Seasonal Processes
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.

Written by: Candy Hansen  (18 April 2007)
Acquisition date
01 April 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
245.4 km (152.5 miles)

Original image scale range
52.9 cm/pixel (with 2 x 2 binning) so objects ~159 cm across are resolved

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50 cm/pixel

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Phase angle

Solar incidence angle
80°, with the Sun about 10° above the horizon

Solar longitude
210.8°, Northern Autumn

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North azimuth:  155°
Sub-solar azimuth:  36.2°
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NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.