Of Polar Pits and Gullies
Of Polar Pits and Gullies
ESP_012873_1075  Science Theme: Aeolian Processes
This image features the north wall and floor of a polar pit in the Southern Hemisphere.

The pit wall is sculpted into a row of gullies. Gullies typically have a triangular start upslope, followed by a channel that transported material, and a triangular debris fan downslope. Polar pit gullies might be related to seasonal changes in frost coverage, but their exact origin is currently unknown. The gullies appear bright because they probably have seasonal frost on them.

The pit floor contains a field of dark sand dunes. Wind has transported sand across the Martian surface, and it was deposited in this pit and formed dunes. Some of the sand in the dunes might have come from the gully debris fans or other erosion of the pit wall.

The bright material within the dunes and along the floor is seasonal frost that is probably composed of carbon dioxide and water ice.

Written by: Kelly Kolb  (10 June 2009)
Acquisition date
25 April 2009

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
252.4 km (156.9 miles)

Original image scale range
50.5 cm/pixel (with 2 x 2 binning) so objects ~152 cm across are resolved

Map projected scale
50 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
57°, with the Sun about 33° above the horizon

Solar longitude
253.7°, Northern Autumn

For non-map projected images
North azimuth:  100°
Sub-solar azimuth:  34.5°
Black and white
map projected  non-map

IRB color
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Merged IRB
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Merged RGB
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RGB color
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Black and white
map-projected   (245MB)

IRB color
map-projected   (113MB)

Black and white
map-projected  (104MB)
non-map           (157MB)

IRB color
map projected  (45MB)
non-map           (130MB)

Merged IRB
map projected  (244MB)

Merged RGB
map-projected  (218MB)

RGB color
non map           (114MB)
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products

IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:

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.