Sorted Boulders on the Northern Plains
Sorted Boulders on the Northern Plains
ESP_019711_2455  Science Theme: Seasonal Processes
This image covers a large crater on the Northern plains of Mars. The crater is old and has been heavily modified by ground ice processes.

The most prominent of these is the network of polygonal fractures visible throughout the image. These form when temperature changes over the course of a year cause ice in the ground to expand, contract, and break. The ground moves fractionally every time this occurs.

At the center of this image, this repetitive process has shifted boulders on the surface, causing them to line up with the fractures and form striking geometric patterns.

Written by: Colin Dundas  (24 November 2010)
Acquisition date
10 October 2010

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
315.2 km (195.9 miles)

Original image scale range
63.3 cm/pixel (with 2 x 2 binning) so objects ~190 cm across are resolved

Map projected scale
50 cm/pixel

Map projection

Emission angle

Phase angle

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

Solar longitude
161.8°, Northern Summer

For non-map projected images
North azimuth:  99°
Sub-solar azimuth:  330.7°
Black and white
map projected  non-map

IRB color
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Merged IRB
map projected

Merged RGB
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RGB color
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IRB color
map-projected   (341MB)

Black and white
map-projected  (460MB)
non-map           (314MB)

IRB color
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non-map           (255MB)

Merged IRB
map projected  (692MB)

Merged RGB
map-projected  (641MB)

RGB color
non map           (238MB)
B&W label
Color label
Merged IRB label
Merged RGB label
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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/JPL/University of Arizona

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.