Fan and Valley within Crater
NASA/JPL/University of Arizona
Fan and Valley within Crater
ESP_020323_2050  Science Theme: Landscape Evolution
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This HiRISE image shows a fan-shaped deposit at the distal end of a valley. The fan is approximately 3.5 x 3.7 kilometers in size.

While other similar fans on Mars display stair-step terracing along their edges, this particular fan does not show any terraces. There is a valley to the upper left that is the source of material that now composes much of the fan.

Martian fans are thought to be either alluvial or deltaic in origin. On Earth, alluvial fans form when material upslope is eroded and transported by water down a confined valley until reaching a flatter, broader surface downslope where the material is deposited to produce a fan-shape.

Deltaic fans form when rivers transport sediment downstream until an unconfined and flatter surface is reached under water, at which time the sediment is deposited in a fan-shape. Whether the Martian fan formed by alluvial or deltaic processes in unknown, but both processes require a fluid (most likely water) that carved the valley and transported the sediment downstream.

Written by: Cathy Weitz   (5 January 2011)

This is a stereo pair with ESP_020824_2050.

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Acquisition date
27 November 2010

Local Mars time:

Latitude (centered)

Longitude (East)

Range to target site
287.1 km (179.4 miles)

Original image scale range
28.7 cm/pixel (with 1 x 1 binning) so objects ~86 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle:

Phase angle:

Solar incidence angle
59°, with the Sun about 31° above the horizon

Solar longitude
188.2°, Northern Autumn

North azimuth:

Sub-solar azimuth:
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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
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IRB color
map-projected   (410MB)

Black and white
map-projected  (460MB)
non-map           (441MB)

IRB color
map projected  (161MB)
non-map           (344MB)

Merged IRB
map projected  (218MB)

Merged RGB
map-projected  (210MB)

RGB color
non map           (330MB)
Map-projected, reduced-resolution
Full resolution JP2 download
Anaglyph details page

B&W label
Color label
Merged IRB label
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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/JPL/University of Arizona

For information about NASA and agency programs on the Web, visit: 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. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.