Layering and Slope Streaks in Henry Crater
Layering and Slope Streaks in Henry Crater
PSP_006569_1915  Science Theme: Sedimentary/Layering Processes
Named after a 19th century French astronomer, Henry Crater is a 165 kilometer (103 mile) diameter impact crater, located in Arabia Terra on a portion of the Martian highlands extending into the northern hemisphere. This observation shows multiple layers on the edge of a mound on the floor of the crater, which is distinct from others in the immediate vicinity.

The layers represent the eroded remains of sedimentary rocks that formed from sediments deposited within the crater sometime after its formation. The origin of the sediments on the crater floor in not known but may be windblown dust and sand. The layers exhibit differences in degrees of hardness and resistance to erosion with resistant layers forming cliffs and more easily eroded layers forming ledges.

Several dark streaks are visible on slopes (see subimage). Slope streak formation is among the few known processes currently active on Mars. Streaks are believed to form by downslope movement of dust in an almost fluid-like manner (analogous to a terrestrial snow avalanche) either exposing darker underlying material or creating a darker surface by increasing its roughness.

Written by: Maria Banks  (30 January 2008)

This is a stereo pair with PSP_007070_1915.
Acquisition date
21 December 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
275.8 km (171.4 miles)

Original image scale range
27.6 cm/pixel (with 1 x 1 binning) so objects ~83 cm across are resolved

Map projected scale
25 cm/pixel and North is up

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Emission angle

Phase angle

Solar incidence angle
37°, with the Sun about 53° above the horizon

Solar longitude
5.8°, Northern Spring

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North azimuth:  97°
Sub-solar azimuth:  353.9°
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NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.