A Circular Crack
NASA/JPL-Caltech/UArizona
A Circular Crack
ESP_029362_1795  Science Theme: Tectonic Processes
This circular crack is very odd-looking. When you zoom in to HiRISE scale, the crack looks a lot like a graben.

Canyonlands, Utah is a great place to see grabens on Earth. Grabens form when solid rock is pulled apart. Two cracks form at distinctive angles, and the material between the cracks collapses downward, forming a straight-walled canyon. Well, they're usually straight-walled, but this one is circular, which is unusual.

The first thing anyone thinks of when they see circular features on Mars is a crater. So one hypothesis about how this formed is that an ancient crater was buried by some material, maybe lava or even multiple layers of wet sediments. Because the center of the crater was deeper, more material settled there, and the high-standing rim was only thinly covered. The mantling material solidified and shrank, creating extensional forces.

The heavy central fill pulled downward, cracking the material at the rim where it was thinnest. That's just one guess, though, what else do you think could it be?

REFERENCES
Buczkowski, D. L. and M. L. Cooke, 2004. Formation of double-ring circular grabens due to volumetric compaction over buried impact craters: Implications for thickness and nature of cover material in Utopia Planitia, Mars, J. Geophys. Res., 109, E02006, doi:10.1029/2003JE002144.

McGill, G. E., 1986. The giant polygons of Utopia, Northern Martian Plains GeoRL 13, 705-708. DOI:10.1029/GL013i008p00705

Written by: Ingrid Daubar  (12 December 2012)

This is a stereo pair with ESP_029217_1795.
 
Acquisition date
31 October 2012

Local Mars time
15:35

Latitude (centered)
-0.454°

Longitude (East)
180.836°

Spacecraft altitude
271.7 km (168.8 miles)

Original image scale range
27.3 cm/pixel (with 1 x 1 binning) so objects ~82 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
5.9°

Phase angle
60.1°

Solar incidence angle
54°, with the Sun about 36° above the horizon

Solar longitude
198.4°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  355.9°
JPEG
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non-map           (222MB)

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non-map           (183MB)

Merged IRB
map projected  (107MB)

Merged RGB
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RGB color
non map           (177MB)
ANAGLYPHS
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Full resolution JP2 download
Anaglyph details page

ADDITIONAL INFORMATION
B&W label
Color label
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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.