Seasonal Erosion
NASA/JPL/University of Arizona
Seasonal Erosion
ESP_029545_0950  Science Theme: Seasonal Processes
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Bright carbon dioxide frost (or, dry ice) highlights this network of channels carved into the surface. The channels are eroded a little bit every spring when the seasonal polar cap, composed of dry ice, sublimates (meaning going directly from a solid to gas) at the ice-surface interface. The erosion occurs under the seasonal ice layer: when trapped pressurized gas finds an escape route it carries along loose surface material. This surface material is blown downwind and deposited in dark fans on top of the seasonal ice layer.

The trapped gas finds the weakest easiest escape route. In this area the gas exploited the existing polygonal structure of the surface below. Polygonal terrain is common at high latitudes, and is caused by the thermal contraction and expansion of water ice frozen in the surface dirt.

Written by: Candy Hansen (audio by Tre Gibbs)   (16 January 2013)

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Acquisition date
14 November 2012

Local Mars time:
17:27

Latitude (centered)
-85.039°

Longitude (East)
259.056°

Range to target site
248.8 km (155.5 miles)

Original image scale range
49.8 cm/pixel (with 2 x 2 binning) so objects ~149 cm across are resolved

Map projected scale
50 cm/pixel

Map projection
Polarstereographic

Emission angle:
5.5°

Phase angle:
82.8°

Solar incidence angle
78°, with the Sun about 12° above the horizon

Solar longitude
206.9°, Northern Autumn

North azimuth:
118°

Sub-solar azimuth:
34.7°
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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
For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. 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.