Polygonal Dunes
NASA/JPL/University of Arizona
Polygonal Dunes
ESP_031138_1380  Science Theme: Fluvial Processes
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Polygons are of great interest because they often indicate the presence of shallow ice or of desiccation such as in a mud flat. However, nature sometimes seems too clever for us.

Polygons form by the intersecting ridges of sand dunes. If this deposit were to become indurated and eroded, we might not be able to tell that they originated as wind-blown dunes, and interpret the polygons as evidence for a dried-up lake, for example. Dunes often accumulate in the bottoms on craters, also a good setting for a (temporary) lake.

The illumination is coming from the upper left, so the bluish ridges are high-standing.

Written by: Alfred McEwen (audio by Tre Gibbs)  (15 May 2013)
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Acquisition date
18 March 2013

Local Mars time:
14:40

Latitude (centered)
-41.433°

Longitude (East)
297.671°

Range to target site
252.4 km (157.8 miles)

Original image scale range
50.5 cm/pixel (with 2 x 2 binning) so objects ~152 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection
Equirectangular

Emission angle:
0.3°

Phase angle:
37.4°

Solar incidence angle
37°, with the Sun about 53° above the horizon

Solar longitude
284.6°, Northern Winter

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  20.9°
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Merged IRB
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Merged RGB
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RGB color
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map-projected   (127MB)

IRB color
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JP2 EXTRAS
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map-projected  (50MB)
non-map           (83MB)

IRB color
map projected  (17MB)
non-map           (83MB)

Merged IRB
map projected  (134MB)

Merged RGB
map-projected  (122MB)

RGB color
non map           (74MB)
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/University of Arizona

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.