Ghost Crater Near the South Pole
NASA/JPL/UArizona
Ghost Crater Near the South Pole
PSP_004980_1035  Science Theme: Polar Geology

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This image shows shows a circular structure near the South Pole of Mars. This feature is probably a heavily modified impact crater. It is currently expressed as a group of concentric circular features with little vertical expression.

This feature was probably once an impact crater many tens of meters deep. (Small impact craters are typically about one-fifth as deep as they are wide). The original topography has been smoothed by some combination of burial and viscous relaxation. Most burial processes will preferentially fill in low areas like craters; the infilling material may then compact, producing arcuate structures.

Creep of the crater wall material may have also played a role in erasing the crater. This far south, the surface material is likely to be ice-rich and will slowly flow downhill. Additional evidence for near-surface ice is provided by the pervasive polygons in the image, forming due to stresses caused by temperature variations in ice-rich ground.

Regardless of the mechanism, the crater remains faintly expressed in the surface morphology. Note that the surface has a similar texture away from the crater, but not organized into concentric arcs. The residual structure of the crater provides some control on stresses, producing the ringed pattern.



Written by: Colin Dundas  (29 August 2007)
 
Acquisition date
19 August 2007

Local Mars time
15:18

Latitude (centered)
-76.491°

Longitude (East)
227.917°

Spacecraft altitude
248.2 km (154.3 miles)

Original image scale range
25.1 cm/pixel (with 1 x 1 binning) so objects ~75 cm across are resolved

Map projected scale
25 cm/pixel

Map projection
Polarstereographic

Emission angle
8.2°

Phase angle
54.8°

Solar incidence angle
60°, with the Sun about 30° above the horizon

Solar longitude
298.4°, Northern Winter

For non-map projected images
North azimuth:  105°
Sub-solar azimuth:  49.7°
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HiView

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IRB: infrared-red-blue
RGB: red-green-blue
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Black & white is 5 km across; enhanced color about 1 km
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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.