Pedestal Crater in the Medusa Fossae Formation
NASA/JPL/UArizona
Pedestal Crater in the Medusa Fossae Formation
PSP_003253_1880  Science Theme: Impact Processes
This image shows a pedestal crater located in a geologic unit on Mars called the Medusa Fossae Formation.

Pedestal craters are produced by differential erosion around impact craters. If the ejecta (material thrown out of the crater) is more resistant to erosion, then the crater and surrounding ejecta will be preserved while the surface is eroded nearby. This causes the ejecta blanket surrounding the crater to form a "pedestal," standing out in relief rather than gradually merging into its surroundings.

There appear to be at least two resistant layers in the material around this pedestal crater, as there are two "steps" in the topography of the pedestal. The subimage, from the long ridge near the top center of the image, shows these steps as well as possible smaller-scale layering.

Despite the detail resolved by HiRISE, it is not clear why the step-forming layers are more resistant. Much of the scene is coated with a mantle of dust which obscures details. Dark slope streaks, likely produced by small avalanches in the dust, are common here. Dust deposition and erosion are also likely the reason for the scalloped texture of mantling material in the crater.



Written by: Colin Dundas  (2 May 2007)
 
Acquisition date
06 April 2007

Local Mars time
15:35

Latitude (centered)
7.713°

Longitude (East)
196.162°

Spacecraft altitude
276.8 km (172.0 miles)

Original image scale range
55.4 cm/pixel (with 2 x 2 binning) so objects ~166 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
1.2°

Phase angle
58.8°

Solar incidence angle
58°, with the Sun about 32° above the horizon

Solar longitude
214.3°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  344.4°
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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.