Polygonal Patterned Ground
NASA/JPL-Caltech/UArizona
Polygonal Patterned Ground
ESP_019669_2450  Science Theme: Glacial/Periglacial Processes
Ice-rich frozen ground on Earth often develops a remarkably regular set of patterns of mounds and interconnected troughs, loosely resembling to a slice of a honeycomb, referred to as “polygonal ground.’ These patterns develop when icy permafrost cracks each winter when the ground cools and contracts.

Over hundreds to thousands of years the surface patterns develop into clearly visible connecting troughs. Typically, these polygons are several meters (yards) or more across. Mud cracks are analogous features that form when wet soil dries and contracts, but are typically form patterns only inches in scale.

Mars experiences seasons and winter cooling fractures the permanently frozen ground in much the same way. As a result, polygonal patterns are wide spread throughout the middle and high latitudes. This image shows an example of such polygonal terrain. Larger impact craters, such as the 400 meter crater visible in the full image, are often muted or reduced to a remnant ring or scattered boulders, partly by infilling and mantling with wind-blown soil and dust. Small craters that are tens of meters (yards) across are mostly absent from this terrain. This image has three maybe four such craters. These large and small crater characteristics suggests to us that this surface is young and has experienced substantial changes over geologically recent times.

The polygons themselves may be partly responsible for keeping the surface “fresh.” As new polygons form over top over existing polygonal patterns they continually churn the surface by developing new troughs and mounds. Indeed, close inspection of seemingly young small craters reveals that polygons rapidly form in the crater interiors and begin to erode the crater walls.

Written by: Mike Mellon  (17 November 2010)
 
Acquisition date
07 October 2010

Local Mars time
15:13

Latitude (centered)
64.746°

Longitude (East)
196.073°

Spacecraft altitude
314.6 km (195.6 miles)

Original image scale range
31.5 cm/pixel (with 1 x 1 binning) so objects ~94 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
0.0°

Phase angle
65.9°

Solar incidence angle
66°, with the Sun about 24° above the horizon

Solar longitude
160.0°, Northern Summer

For non-map projected images
North azimuth:  98°
Sub-solar azimuth:  331.4°
JPEG
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IRB color
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Merged IRB
map projected

Merged RGB
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RGB color
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JP2
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JP2 EXTRAS
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map-projected  (300MB)
non-map           (314MB)

IRB color
map projected  (89MB)
non-map           (225MB)

Merged IRB
map projected  (225MB)

Merged RGB
map-projected  (216MB)

RGB color
non map           (225MB)
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.