Dry Ice and Dunes
Dry Ice and Dunes
PSP_007494_2580  Science Theme: Aeolian Processes
Mars has a vast sea of sand dunes in the high latitude region encircling its North polar cap, known as the North polar erg. These dunes are made up of basalt and gypsum sand grains.

In some regions of the North polar erg where the sand supply is limited they take on an elongated crescent shape (see PSP_009324_2650). The icy ground that the dunes are on top of has irregular polygonal patterns. In other areas with an abundant supply of sand the dunes are continuous.

The entire North polar erg is covered in the winter with a seasonal polar cap composed of carbon dioxide (dry ice). In the springtime this seasonal polar cap evaporates. This image shows the dunes mostly still covered with dry ice, but the dark spots are places where the ice has evaporated and the dark sand of the dune is visible.

Written by: Candy Hansen  (9 June 2008)
Acquisition date
02 March 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
319.7 km (198.7 miles)

Original image scale range
from 32.2 cm/pixel (with 1 x 1 binning) to 64.3 cm/pixel (with 2 x 2 binning)

Map projected scale
25 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
64°, with the Sun about 26° above the horizon

Solar longitude
39.5°, Northern Spring

For non-map projected images
North azimuth:  106°
Sub-solar azimuth:  315.1°
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   (1524MB)

IRB color
map-projected   (733MB)

Black and white
map-projected  (789MB)
non-map           (506MB)

IRB color
map projected  (335MB)
non-map           (580MB)

Merged IRB
map projected  (451MB)

Merged RGB
map-projected  (416MB)

RGB color
non map           (515MB)
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.