North Polar Dunes
North Polar Dunes
PSP_007779_2570  Science Theme: Seasonal Processes
In this image, we can see that the north pole is surrounded by a vast “sea” of basaltic sand dunes. In northern winter a seasonal polar cap composed of carbon dioxide ice (dry ice) forms and the surrounding dunes become covered with frost. In the spring, the ice sublimates (evaporates directly from ice to gas) loosening and moving tiny dust particles.

The bright portions of the dunes in this image are areas still covered with seasonal frost while dark spots are areas where the frost is gone or dark dust has cascaded down the sides of the dune.

The dunes imaged here are similar to barchan dunes that are commonly found in desert regions on Earth. Barchan dunes are generally crescent-shaped with a steep slip face bordered by horns oriented in the downwind direction. Barchan dunes form by winds blowing mainly in one direction and thus are good indicators of the dominant wind direction when the dunes formed.

Written by: Maria Banks  (16 April 2008)
Acquisition date
24 March 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
315.9 km (196.3 miles)

Original image scale range
31.6 cm/pixel (with 1 x 1 binning) so objects ~95 cm across are resolved

Map projected scale
25 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
60°, with the Sun about 30° above the horizon

Solar longitude
49.4°, Northern Spring

For non-map projected images
North azimuth:  102°
Sub-solar azimuth:  318.5°
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   (2390MB)

IRB color
map-projected   (1052MB)

Black and white
map-projected  (1180MB)
non-map           (938MB)

IRB color
map projected  (319MB)
non-map           (737MB)

Merged IRB
map projected  (609MB)

Merged RGB
map-projected  (572MB)

RGB color
non map           (679MB)
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.