Two Craters South of Sirenum Fossae
Two Craters South of Sirenum Fossae
ESP_012997_1445  Science Theme: Landscape Evolution
This image shows two craters in the southern hemisphere just south of Sirenum Fossae.

The northern crater is smaller, appears more degraded, and is partially filled with sediments that form a hummocky surface. Dunes have formed subsequently on this surface. Some incipient gully-like features have formed midway along the southern crater wall and expose layers that are more resistant to erosion.

The larger crater to the south is eroded by gullies on its northern slope while the southern slope region lacks them. Most gullies in this scene appear to emanate from more resistant layers, although the larger gullies have eroded back almost to the crater rim.

The nature of the layers and their connection to the water that formed the gullies is unknown. Gullies typically form when flowing water erodes sediments and soft rocks in a channelized flow. Because Mars is very cold and dry, it is unknown where the water came from to form the gullies.

Written by: Kate Coleman & Ginny Gulick  (3 June 2009)
Acquisition date
05 May 2009

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
251.3 km (156.2 miles)

Original image scale range
50.3 cm/pixel (with 2 x 2 binning) so objects ~151 cm across are resolved

Map projected scale
50 cm/pixel and North is up

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Emission angle

Phase angle

Solar incidence angle
43°, with the Sun about 47° above the horizon

Solar longitude
259.8°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  6.1°
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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.