Gullies of Crater Wall in Terra Sirenum
Gullies of Crater Wall in Terra Sirenum
PSP_006760_1370  Science Theme: Fluvial Processes
This image shows pole-facing gullies in a southern hemisphere crater. Gullies are young features that are widely thought to form from fluvial processes involving liquid water. These particular gullies have very fine channels, including some that intersect and overlap. This is evidence that multiple flow events occurred within the gullies.

The wavy, arcuate ridges at the bottom of the slope may have formed by gravity moving ice-rich material off the crater wall. The pitted texture of the crater floor suggests that volatiles (ices that easily turn into gas) escaped from the subsurface, causing the surrounding material to collapse and form small pits.

Written by: Kelly Kolb  (21 May 2008)
Acquisition date
05 January 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
250.9 km (155.9 miles)

Original image scale range
25.4 cm/pixel (with 1 x 1 binning) so objects ~76 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
60°, with the Sun about 30° above the horizon

Solar longitude
13.0°, Northern Spring

For non-map projected images
North azimuth:  95°
Sub-solar azimuth:  47.7°
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Black & white is 5 km across; enhanced color about 1 km
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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.