Banded Ridges in Hellas
NASA/JPL/University of Arizona
Banded Ridges in Hellas
ESP_033995_1410  Science Theme: Composition and Photometry
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Low lying areas in the Hellas region--which is the largest impact basin on Mars--often show complex groups of banded ridges, furrows, and pits. These sorts of bands suggest that the surface material has flowed and twisted viscously like taffy. The orientation of the ridges and groups of ridges would then point in the direction of the flow, called stream lines.

Making this landscape even more complex is when we see that the ridges are sometimes disconnected. They stop abruptly, break up into blocky segments that sometimes appear offset. Such mixed up fragments give an initial sense that parts of the flow have been rafted apart from one another. Alternatively, the entire region may be substantially eroded since the time when the taffy-like ridges actually formed. In that case, the flow may have been far more complex and three dimensional, such that the disconnected portions are actually areas where the flow transitioned up and down relative to the current plane of the eroded surface. In this way we only see a slice through a far more complex series of twists and bends, some of which is still buried beneath the ground.

What this taffy-like material is made of is currently unknown. Hard and soft rocks, as well as ice and ice-rich rocky debris, can deform and flow given time under the force of gravity and the pressures found deep beneath the surface. Afterwards, differential erosion of hard and soft rock or icy materials mixed in bands and layers might give rise to the ridges, furrows and pits which we observe today.

Written by: Mike Mellon (audio by Tre Gibbs)   (9 January 2014)

This is a stereo pair with ESP_042382_1410.

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Acquisition date
27 October 2013

Local Mars time:

Latitude (centered)

Longitude (East)

Range to target site
259.2 km (162.0 miles)

Original image scale range
51.9 cm/pixel (with 2 x 2 binning) so objects ~156 cm across are resolved

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50 cm/pixel and North is up

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Solar incidence angle
69°, with the Sun about 21° above the horizon

Solar longitude
41.3°, Northern Spring

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For information about NASA and agency programs on the Web, visit: 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. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.