Stars and Stripes
Stars and Stripes
ESP_015900_1465  Science Theme: Climate Change
Although this image was primarily taken to study the gullies in the inner walls of the crater it also reveals a few other interesting things. Near the gullies in the northern wall of the crater some boulders have bounced down the slope, leaving trails of hollows along their paths.

This image also shows a nice example of different types of dunes in close proximity to each other: North is at roughly 3 o-clock in this subimage. On either side of this mound on the southern end of the crater floor, there are different types of dunes. On the south side of the mound (left side of the cutout), there are "star dunes" (named for the star-like intersections of their crests). These types of dunes are formed when the wind blows in multiple directions. For more information on star dunes, see ESP_017036_1665 and PSP_008323_1735.

On the north side of the mound (the right when looking at the cutout), there are simpler dune shapes, forming roughly straight, parallel lines. Notice that the same side of each dune is steeper. These are called linear dunes, and are formed by wind blowing mainly parallel to the direction of the crests, probably with some variation to one side or the other that causes the asymmetrical slopes. The linear dunes transition to the star dunes near the mound. Since the main factor controlling which type of dunes form is wind direction, there must have been different wind directions in this area, perhaps caused by wind blowing around the mound itself or interacting with the nearby crater wall.

Written by: Ingrid Daubar  (8 March 2010)
Acquisition date
17 December 2009

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
253.7 km (157.7 miles)

Original image scale range
25.7 cm/pixel (with 1 x 1 binning) so objects ~77 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
24.9°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  46.5°
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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’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.