Fretted Terrain Valley Traverse
Fretted Terrain Valley Traverse
PSP_009719_2230  Science Theme: Glacial/Periglacial Processes
This observation shows fretted terrain in valleys located in Protonilus Mensae near the crustal dichotomy, the region that separates the Southern hemisphere highlands from the Northern hemisphere lowlands.

Fretted terrain is thought to involve movement of ice-rich material in its formation. The speckled texture of the valley fill (the fretted terrain) is probably due to sublimation, when ice goes directly from a solid to a gas, leaving behind empty space under the soil into which overlying material can collapse.

The linear striations in the valley fill mark the direction of movement. For example, in the valley near the top of the image, the material was moving across the scene (probably to the right based on images from other datasets). Also in this scene, are several small craters in various stages of degradation.

Written by: Kelly Kolb  (17 December 2008)
Acquisition date
22 August 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
295.5 km (183.6 miles)

Original image scale range
59.1 cm/pixel (with 2 x 2 binning) so objects ~177 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
46°, with the Sun about 44° above the horizon

Solar longitude
116.4°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  356.6°
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Black & white is 5 km across; enhanced color about 1 km
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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.