>   HiROC   >   images   >   TRA   >   TRA_000856_2265

Scalloped Pits in the Northern Plains

HiRISE Image TRA_000856_2265

This image in the Utopia Planitia region is marked by large somewhat circular pits roughly tens of meters (yards) deep, with scalloped edges. The presence of these pits has lead to hypotheses of the removal of subsurface material, possibly ice by sublimation (evaporation) since no channels are observed to imply melting. Close up, the upper surface is arrayed with a polygonal pattern of fractures in a variety of regular and irregular orientations. These fractures indicated that a competent or cohesive surface layer is present that has undergone stress, in much the same way paint cracks as it dries and shrinks. Although, in this geologic context of the middle latitudes of Mars, stress might be caused by subsidence, desiccation, or thermal contraction. The scalloped walls and some of the floor area of these pits are peppered with smaller polygonal patterns only 10 meters (yards) across. The change in crack pattern may indicate a change in the strength of subsurface material, a change in the forces inducing stress, or both. Other areas of the of the floors of these pits are hummocky with scattered rocks.

Image TRA_000856_2265 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on October 2, 2006. The complete image is centered at 46.0 degrees latitude, 92.0 degrees East longitude. The range to the target site was 300.5 km (187.8 miles). At this distance the image scale ranges from 30.1 cm/pixel (with 1 x 1 binning) to 120.3 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 3:17 PM and the scene is illuminated from the west with a solar incidence angle of 46 degrees, thus the sun was about 44 degrees above the horizon. At a solar longitude of 114.7 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:




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 Product Pixel Dimensions File Size
Small JPG 512
Large JPG 2048
Full-Scale JP2 25835
Products for TRA_000856_2265

The highest resolution image is provided in the JPEG-2000 (JP2) format. A JP2 viewer application and browser plug-in may be freely obtained for Mac OS X and Windows platforms: ExpressView by LizardTech, a Celartem Technology Inc. company.

Learn more about HiRISE at these sites: