Frosty Gullies on the Northern Plains
NASA/JPL/University of Arizona
Frosty Gullies on the Northern Plains
ESP_040811_2410  Science Theme: Mass Wasting Processes
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Seasonal frost commonly forms at middle and high latitudes on Mars, much like winter snow on Earth. However, on Mars most frost is carbon dioxide (dry ice) rather than water ice. This frost appears to cause surface activity, including flows in gullies.

This image shows frost in gully alcoves in a crater on the Northern plains. The frost highlights details of the alcoves, since it forms in different amounts depending on slopes and shadows as well as the type of material making up the ground. Rugged rock outcrops appear dark and shadowed, while frost highlights the upper alcove and the steepest route down the slope.

Most changes associated with gullies are observed in the Southern hemisphere. However, some are seen in the Northern hemisphere, where steep slopes are less common. HiRISE is monitoring these gullies to look for changes and to understand the behavior of the frost.

Written by: Colin Dundas (audio by Tre Gibbs)  (15 July 2015)
 
Acquisition date
11 April 2015

Local Mars time
13:54

Latitude (centered)
60.562°

Longitude (East)
89.425°

Spacecraft altitude
308.7 km (191.9 miles)

Original image scale range
61.9 cm/pixel (with 2 x 2 binning) so objects ~186 cm across are resolved

Map projected scale
50 cm/pixel and North is up

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Equirectangular

Emission angle
3.7°

Phase angle
80.9°

Solar incidence angle
78°, with the Sun about 12° above the horizon

Solar longitude
324.0°, Northern Winter

For non-map projected images
North azimuth:  98°
Sub-solar azimuth:  305.9°
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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.