Ancient Terrain Near Tyrrhena Patera
This observation covers a small part of the plains surrounding the volcano Tyrrhena Patera.
Most of this area is covered by a thick layer of "mantling" material which hides the underlying rocks. Infrared data from the Mars Odyssey spacecraft suggested that this area is rockier than most of the region.
The HiRISE observation confirms that the area is unusually rocky, with some bare patches of ancient shattered rock exposed at the surface. This image is also a good example of how the HiRISE team samples unknown terrain. The center of the image is at full resolution, but the outer edges have averaged each group of 4 x 4 pixels. This reduces the amount of data that needs to be returned to Earth and helps ascertain how much resolution is actually needed to study this kind of terrain.
Image PSP_001674_1610 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 04-Dec-2006. The complete image is centered at -18.8 degrees latitude, 105.0 degrees East longitude. The range to the target site was 256.8 km (160.5 miles). At this distance the image scale ranges from 25.7 cm/pixel (with 1 x 1 binning) to 102.8 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 03:36 PM and the scene is illuminated from the west with a solar incidence angle of 63 degrees, thus the sun was about 27 degrees above the horizon. At a solar longitude of 145.4 degrees, the season on Mars is Northern Summer.