Boulders Inside a Rimless Martian Pit (Stretched)

This enhanced image shows the inside of a rimless pit about 310 meters (1,017 feet) in diameter, northwest of the mountain Ascraeus Mons in the northern hemisphere of Mars. The pit has a very steep eastern wall (on the right) and more gently sloped western wall. Shadows and overhangs obscure some of the interior, but this stretched-brightness image shows boulders on the floor.

The image is part of an observation made by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter on Nov. 1, 2010. The terrain covered in the observation includes two dark pits apparently aligned with larger, degraded depressions. Other image products from this observation are available at http://hirise.lpl.arizona.edu/ESP_019997_1975.

Careful study of the walls and floors of the pits, as well as of the surrounding terrain, will help unravel the complicated series of processes that must have been responsible for their formation and subsequent modification.

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, Denver, built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo.