HiRISE at One Year: Student Image of the Week-Seasonal Changes of South Polar Dark Dune Field
HiRISE at One Year: Student Image of the Week-Seasonal Changes of South Polar Dark Dune Field
PSP_003609_1110  Science Theme: Fluvial Processes
This image was suggested by Andras Sik's SUPERNOVA astronomy and space research class at the Alternative Secondary School of Economics in Budapest, Hungary.

They interpret the image: "During local springtime, a varying albedo pattern can be observed on the surface of dark intracrater dune fields in the southern polar region of Mars. The origin of dark dune spots and the dark slope streaks emanating from them is yet uncertain. There are several possible explanations for these phenomena, like "sublimation of carbon-dioxide frost cover", "dusty carbon-dioxide gas eruptions through the frost cover" and "transient liquid water-formation under layered water-ice/carbon dioxide-ice cover". In this HiRISE image the distribution of dark streaks are not chaotic and their shapes are not fan-like; rather they are composed of confined, dozen-hundred meter long branches which follow the local topography and have accumulation zones at their end."

We are learning a great deal from the enigmatic dark spots that are found throughout the south polar region. These dark spots may have resulted from cold gas jets that form by sublimation of the ice bringing entrained dust to the surface. Small dark streaks may have formed by avalanches of sand or they may be patches of coarse-grained ice that are clear enough so that the dark material below the ice is visible.

The color image also provides helpful clues to understand this process. Bright white frost can be seen covering the surface. This frost is a probably a combination of frozen water and carbon dioxide ice. These bright patches are particularly prevalent along dune slip faces and around dark spots.

Written by: Alix Davatzes (HiRISE challenge caption)  (7 November 2007)
Acquisition date
04 May 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
250.0 km (155.4 miles)

Original image scale range
25.0 cm/pixel (with 1 x 1 binning) so objects ~75 cm across are resolved

Map projected scale
25 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
61°, with the Sun about 29° above the horizon

Solar longitude
231.5°, Northern Autumn

For non-map projected images
North azimuth:  98°
Sub-solar azimuth:  31.0°
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Black & white is 5 km across; enhanced color about 1 km
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All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:

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.