The Draa of Mars
NASA/JPL-Caltech/UArizona
The Draa of Mars
ESP_034909_1755  Science Theme: Aeolian Processes
Sandy landforms formed by the wind or aeolian bedforms are classified by the wavelength—or length—between crests. On Mars we can observe four classes of bedforms (in order of increasing wavelengths): ripples, transverse aeolian ridges (known as TARs), dunes, and what are called “draa.” All of these are visible in this Juventae Chasma image.

Ripples are the smallest bed forms (less than 20 meters) and can only be observed in high-resolution images acquired by HiRISE commonly superposed on many surfaces. TARs are slightly larger bedforms (wavelengths approximately 20 to 70 meters), which are often light in tone relative to their surroundings. Dark-toned dunes (wavelengths 100 meters to 1 kilometer) are a common landform and many are active today. What geologists call “draa” is the highest-order bedform with largest wavelengths ( greater than 1 kilometer), and is relatively uncommon on Mars.

Here, this giant draa possess steep faces or slip faces several hundreds of meters tall and has lower-order superposed bedforms, such as ripples and dunes. A bedform this size likely formed over thousands of Mars years, probably longer.

Written by: Matthew Chojnacki (narration: Tre Gibbs)  (4 June 2014)
 
Acquisition date
06 January 2014

Local Mars time
15:12

Latitude (centered)
-4.500°

Longitude (East)
297.183°

Spacecraft altitude
266.7 km (165.8 miles)

Original image scale range
26.7 cm/pixel (with 1 x 1 binning) so objects ~80 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
3.0°

Phase angle
52.7°

Solar incidence angle
55°, with the Sun about 35° above the horizon

Solar longitude
72.7°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  39.7°
JPEG
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

JP2
Black and white
map-projected   (821MB)

IRB color
map-projected   (512MB)

JP2 EXTRAS
Black and white
map-projected  (357MB)
non-map           (497MB)

IRB color
map projected  (145MB)
non-map           (421MB)

Merged IRB
map projected  (192MB)

Merged RGB
map-projected  (181MB)

RGB color
non map           (405MB)
ADDITIONAL INFORMATION
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products
HiView

NB
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

USAGE POLICY
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/JPL-Caltech/UArizona

POSTSCRIPT
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.