Defrosted Margin of the North Polar Erg
Defrosted Margin of the North Polar Erg
PSP_009396_2590  Science Theme: Aeolian Processes
This image shows a traverse across a section of the North Polar erg, a vast sea of sand that surrounds the polar cap.

The source of the dunes may be from the eroding north polar layered deposits. Wind, acting on this mixture of sand, dust, and ice, has formed several dune types on top of bright megaripples and polygons. A dark mantle of sand lies beyond the dunes.

The central part of the field contains transverse dunes with the dominant wind direction coming from the northwest-west. The outer edges of the dune field transition into star dunes (with multiple arms) and barchanoid dunes (crescent-like shape). The star dunes indicate a multidirectional wind regime or a change in wind direction over the dune field's evolution. The dunes are somewhat confined to their location and may have taken hundreds of years to form.

Written by: Circe Verba  (3 September 2008)
Acquisition date
28 July 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
317.3 km (197.2 miles)

Original image scale range
from 31.7 cm/pixel (with 1 x 1 binning) to 63.5 cm/pixel (with 2 x 2 binning)

Map projected scale
25 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
57°, with the Sun about 33° above the horizon

Solar longitude
104.9°, Northern Summer

For non-map projected images
North azimuth:  105°
Sub-solar azimuth:  325.0°
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   (1517MB)

IRB color
map-projected   (794MB)

Black and white
map-projected  (714MB)
non-map           (457MB)

IRB color
map projected  (324MB)
non-map           (622MB)

Merged IRB
map projected  (426MB)

Merged RGB
map-projected  (406MB)

RGB color
non map           (608MB)
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.