Sample of Ancient Mesa Near Tyrrhena Patera
HiRISE Image TRA_000869_1605This HiRISE image samples the top of a mesa that is a remnant of the ancient crust that is mostly found in the southern half of Mars. As expected, the surface is covered with a mix of impact craters, dust, and sand. Somewhat surprisingly, the mixture is very uneven. Large patches of the mesa appear covered only with boulders a few meters in diameter. Such small boulders could not be recognized in previous orbital images. These boulder patches may represent exposed sections of the battered ancient crust. Scientists refer to such pervasively broken rock as a "megabreccia". Sand dunes are predominantly found inside craters, where the sand grains are trapped while smooth, dust-covered ground is found filling many shallow depressions.
Image TRA_000869_1605 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on October 3, 2006. The complete image is centered at -19.2 degrees latitude, 106.0 degrees East longitude. The range to the target site was 255.6 km (159.8 miles). At this distance the image scale ranges from 25.6 cm/pixel (with 1 x 1 binning) to 102.3 cm/pixel (with 4 x 4 binning). The image shown here has been map-projected to 25 cm/pixel and north is up. The image was taken at a local Mars time of 3:31 PM and the scene is illuminated from the west with a solar incidence angle of 66 degrees, thus the sun was about 24 degrees above the horizon. At a solar longitude of 115.2 degrees, the season on Mars is Northern Summer.
Images from the High Resolution Imaging Science Experiment and additional information about the Mars Reconnaissance Orbiter are available online at:
http://hirise.lpl.arizona.edu/
or
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.
