Fans on Ice
Fans on Ice
ESP_011351_0945  Science Theme: Seasonal Processes
Every southern winter the south polar region of Mars is covered with an approximately 1 meter deep layer of frozen carbon dioxide (dry ice). In the spring, when the sun begins to warm the surface below the translucent ice, gas flow under the ice carries loose dust from the surface up onto the top.

The dust falls to the surface in fans, whose orientation is determined by the direction of the local wind flow. Fans from one source region pointing in multiple directions show how the wind direction has changed. Narrow fans pointing in just one direction are the most recent. Alternatively, the vent from the surface may have re-annealed, such that these fans were formed over a very limited time span.

Written by: Candy Hansen  (18 February 2009)

This is a stereo pair with ESP_011350_0945.
Acquisition date
27 December 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
247.0 km (153.5 miles)

Original image scale range
99.0 cm/pixel (with 4 x 4 binning) so objects ~297 cm across are resolved

Map projected scale
100 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
90°, with the Sun about 0° above the horizon

Solar longitude
181.2°, Northern Autumn

For non-map projected images
North azimuth:  127°
Sub-solar azimuth:  32.6°
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
map projected

RGB color
non-map projected

Black and white
map-projected   (237MB)

IRB color
map-projected   (128MB)

Black and white
map-projected  (172MB)
non-map           (157MB)

IRB color
map projected  (86MB)
non-map           (144MB)

Merged IRB
map projected  (249MB)

Merged RGB
map-projected  (235MB)

RGB color
non map           (139MB)
Map-projected, reduced-resolution
Full resolution JP2 download
Anaglyph details page

B&W label
Color label
Merged IRB label
Merged RGB label
EDR products

IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

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.