Scalloped Terrain at Peneus Patera
Scalloped Terrain at Peneus Patera
PSP_004274_1225  Science Theme: Climate Change


This image is located on the northwestern flank of the volcano Peneus Patera, southwest of Hellas Basin.

The terrain consists of a rough, pitted lower surface and a relatively, smooth upper surface. The lower surface forms oval- to scalloped-shaped edge depressions, several of which have coalesced together. Typically these depressions have a steep pole-facing scarp and a gentler equator-facing slope. The pitted texture of this lower terrain may have formed by the removal of subsurface ice by sublimation, as at this latitude on Mars, the pressure and temperature conditions allow interstitial ground ice to sublime, possibly leading to the formation of depressions.

For example, the roughly circular feature at the top of the image was probably an ancient crater that was filled with the smooth material, possibly composed of ash and dust mixed with interstitial ice. Sublimation of this material subsequently occurred following the crater rim, leaving this circular pattern.

Written by: Alexandra Lefort  (15 August 2007)

This is a stereo pair with PSP_005698_1225.
Acquisition date
25 June 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
249.5 km (155.1 miles)

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

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
47°, with the Sun about 43° above the horizon

Solar longitude
264.3°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  28.7°
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Black and white
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non-map           (593MB)

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non-map           (426MB)

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RGB color
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Map-projected, reduced-resolution
Full resolution JP2 download
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IRB: infrared-red-blue
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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.