Colorful Dunes
Colorful Dunes
ESP_033272_1400  Science Theme: Aeolian Processes
This field of dunes lies on the floor of an old crater in Noachis Terra, one of the oldest places on Mars.

When there are perfect conditions for producing sand dunes—steady wind in one direction and just enough sand—barchan sand dunes form. The word “barchan” is a Russian term because this type of dune was first described in the desert regions of Turkistan.

Barchans have a gentle slope on the upwind side and a much steeper slope on the lee side where horns or a notch often forms. The wind in this case came from the southwest. Observing dunes on Mars can tell us how strong the winds are, as well as their direction. If pictures are taken at regular intervals, one may see changes in the dunes and in ripples on the dunes’ surface.

The color in the photograph is not the same as we would see with our eyes because an extra color (infrared) is added. Our eyes cannot detect infrared, but it is used because it can give us clues to the composition of the surface. On Mars dunes are often dark in color because they were formed from the common, volcanic rock basalt. In the dry environment, dark minerals in basalt, like olivine and pyroxene, do not break down as quickly as they do on Earth. Although rare, some dark sand is found on Earth, for example in Hawaii which also has many volcanoes discharging basalt.

Written by: James Secosky (narration: Tre Gibbs)  (2 October 2013)
Acquisition date
01 September 2013

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
254.1 km (157.9 miles)

Original image scale range
51.7 cm/pixel (with 2 x 2 binning) so objects ~155 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
59°, with the Sun about 31° above the horizon

Solar longitude
15.4°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  48.3°
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   (121MB)

IRB color
map-projected   (71MB)

Black and white
map-projected  (50MB)
non-map           (72MB)

IRB color
map projected  (17MB)
non-map           (71MB)

Merged IRB
map projected  (128MB)

Merged RGB
map-projected  (117MB)

RGB color
non map           (65MB)
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.