Utopia Planitia Scallops, Polygons, and Boulders
Utopia Planitia Scallops, Polygons, and Boulders
ESP_025620_2275  Science Theme: Glacial/Periglacial Processes
This terrain is covered by pits and scallops (pits open on one side), perhaps due to collapse after sublimation of subsurface ice.

This full-resolution 3D sample shows that the surface is cut into many polygons about 10 meters wide, that form as ice expands and contracts with temperature changes. There are also many meter-scale boulders on the surface, which must be rocks rather than blocks of ice, or they would not be stable on the surface.

More than 10 meters thickness of ice must have sublimated from some areas. (Sublimation is the process of going from a solid directly to a gas). How did the ice get deposited? One idea is that it is from snowfall (in a different climate), but then it is difficult to explain the presence of the boulders. The other possibility is transport through the shallow subsurface in very thin films of water over many years.

Written by: Alfred McEwen  (22 February 2012)

This is a stereo pair with ESP_025277_2275.
Acquisition date
13 January 2012

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
301.5 km (187.4 miles)

Original image scale range
33.3 cm/pixel (with 1 x 1 binning) so objects ~100 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
45°, with the Sun about 45° above the horizon

Solar longitude
56.6°, Northern Spring

For non-map projected images
North azimuth:  94°
Sub-solar azimuth:  340.5°
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IRB color
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Black and white
map-projected  (704MB)
non-map           (625MB)

IRB color
map projected  (257MB)
non-map           (553MB)

Merged IRB
map projected  (497MB)

Merged RGB
map-projected  (481MB)

RGB color
non map           (537MB)
Map-projected, reduced-resolution
Full resolution JP2 download
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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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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.