Stone Circles
Stone Circles
ESP_030222_1220  Science Theme: Future Exploration/Landing Sites
This image covers a region southeast of the giant Hellas impact basin, which has distinctive properties in THEMIS temperature images.

The daytime temperatures are relatively cold while nighttime temperatures are relatively warm. This tells us that the surface material conducts heat efficiently, like rocks rather than fine-grained materials.

This image shows lots of boulders, and in places they form crude circular patterns. This could be due to the effects of many small impact craters (which we can no longer see, except perhaps for the boulder patterns). An alternative idea is that active processes on Mars can move large boulders (up to several meters in diameter) little by little over time.

There is almost certainly ice in the ground at this latitude (58 degrees south latitude), which expands and contracts with temperature changes. Those temperature stresses combined with the removal of fine-grained materials by the wind might be able to organize the boulders. Another idea is that in a recent past, climate the ice could seasonally melt, then re-freeze, which leads to stone circles in terrestrial permafrost (ground that is largely frozen throughout the year).

Written by: Alfred McEwen (narration: Tre Gibbs)  (24 January 2013)
Acquisition date
06 January 2013

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
248.8 km (154.6 miles)

Original image scale range
49.8 cm/pixel (with 2 x 2 binning) so objects ~149 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
53°, with the Sun about 37° above the horizon

Solar longitude
239.6°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  26.6°
Black and white
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IRB color
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Merged IRB
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Merged RGB
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Black and white
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IRB color
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Black and white
map-projected  (46MB)
non-map           (85MB)

IRB color
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non-map           (92MB)

Merged IRB
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Merged RGB
map-projected  (138MB)

RGB color
non map           (88MB)
B&W label
Color label
Merged IRB label
Merged RGB label
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RGB: red-green-blue
About color products (PDF)

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’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.