Dunes in Late Fall: Frost in the Ripples
NASA/JPL-Caltech/UArizona
Dunes in Late Fall: Frost in the Ripples
ESP_025679_1300  Science Theme: Aeolian Processes
These dunes in Aonia Terra are being monitored for changes such as gullies, which form over the winter from the action of carbon dioxide frost.

The season in which this image was acquired was late fall in the Southern hemisphere. Frost is just starting to accumulate here, and is concentrated on pole-facing slopes and in the troughs between the meter-scale ripples. The colors have been enhanced in the cutout.

Written by: Alfred McEwen  (22 February 2012)
 
Acquisition date
18 January 2012

Local Mars time
15:10

Latitude (centered)
-49.818°

Longitude (East)
293.112°

Spacecraft altitude
250.1 km (155.4 miles)

Original image scale range
50.0 cm/pixel (with 2 x 2 binning) so objects ~150 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
0.3°

Phase angle
82.9°

Solar incidence angle
83°, with the Sun about 7° above the horizon

Solar longitude
58.6°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  52.2°
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non-map           (154MB)

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Merged IRB
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Merged RGB
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RGB color
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HiView

NB
IRB: infrared-red-blue
RGB: red-green-blue
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Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

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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-Caltech/UArizona

POSTSCRIPT
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.