Crater Floor Fan
Crater Floor Fan
PSP_008233_1920  Science Theme: Fluvial Processes
This image shows a fan of material deposited on the floor of a large impact crater.

The material was transported into the crater through a valley, likely by running water. The end of the valley is visible in the west (left) part of the image. Arcuate steps visible in the east are probably due to layers of different strength or cohesion; these suggest variations in the flow conditions.

A faint trough is carved into the upper surface of the fan. This could have been cut by the last water to flow across the surface. If the channel was flowing into a lake, this might indicate a drop in lake level, leading to erosion.

The surface of the fan has many small dark spots, particularly on the upper tier. The largest spots, most commonly around impact craters, are big enough to show that these are boulders. If these boulders are original and not due to the hardening of fan sediments into rock, it suggests that the flows which deposited the fan were relatively energetic events able to carry rocks across several feet.

Written by: Colin Dundas  (11 June 2008)

This is a stereo pair with PSP_008879_1920.
Acquisition date
29 April 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
275.6 km (171.3 miles)

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

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
46°, with the Sun about 44° above the horizon

Solar longitude
64.9°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  25.8°
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RGB color
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Black & white is 5 km across; enhanced color about 1 km
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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

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.