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Sample of the Argyre Impact Basin Rim
04.07.06
image shows part of a low mountain belt that rings the Argyre impact basin in Mars' southern hemisphere

This image shows part of a low mountain belt that rings the Argyre impact basin in Mars' southern hemisphere. The mountains or hills seen here are located in the northwestern part of the Charitum Montes. Taken just minutes after the sun had risen over the horizon, only the sun-facing slopes are well illuminated and much of the scene is in shadow, but the camera has nevertheless captured many details of the surface that are only dimly illuminated. There are terrains that are both smooth and rough at this scale (2.94 meters or 9.65 feet per pixel). The rough terrain is littered with blocks roughly 10 meters (30 feet) across, and the smooth material has a uniform appearance broken by subtle, undulating ridges. The rough terrains usually occur at relatively high elevations, and smooth material occupies the lowest areas. In some locations it is evident that boulders from the rough terrain have tumbled downhill onto the smooth material. The smooth material is younger than the rough terrain, and some of it may have formed when water-rich or ice-rich debris flooded low-lying areas. In other areas the smooth material mantles the topography like deposits of airborne dust. Further upslope, the mountain flanks have a variety of rough textures. In places the terrain has been eroded into streamlined forms and striations, suggestive of glacial erosion. Gullies formed in one spot near bottom center. Perhaps the most striking aspect of this image is the dearth of fresh impact craters. The Argyre basin is thought to be billions of years old, but much more recent processes have greatly modified the surface.

This image was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard NASA's Mars Reconnaissance Orbiter spacecraft on March 24, 2006. The image is centered at 52.20 degrees south latitude, 300.75 degrees east longitude. It is oriented such that north is 7 degrees to the left of up. The range to the target was 1,470 kilometers (913 miles). With 2x2 pixel binning, the scale of the image is 2.94 meters (9.65 feet) per pixel, so objects as small as 8.82 meters (28.94 feet) are resolved. In total this image is 29.47 kilometers (18.31 miles) or 10,040 pixels wide and 76.44 kilometers (47.50 miles) or 26,011 pixels long. The image was taken at a local Mars time of 07:24 and the scene is illuminated from the upper right with a solar incidence angle of 87.1 degrees, thus the sun was about 2.9 degrees above the horizon. At an Ls of 29 degrees (with Ls an indicator of Mars' position in its orbit around the sun), the season on Mars is southern autumn.

Images from the High Resolution Imaging Science Experiment and additional information about the Mars Reconnaissance Orbiter are available online at: http://www.nasa.gov/mro or http://HiRISE.lpl.arizona.edu. 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, 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.

Image Credit: NASA/JPL-Caltech/University of Arizona

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