Aonia Terra Periglacial Sample
Aonia Terra Periglacial Sample
ESP_013958_1170  Science Theme: Glacial/Periglacial Processes
Throughout this entire image in Aonia Terra, it is possible to make out regular polygonally shaped patterns. Here on Earth, wherever ice-rich permafrost occurs (soil which stays frozen throughout the year), the ground may crack and form similar patterns to those we see on Mars.

Despite remaining below freezing, changes in seasons and ground temperature cause significant thermal-contraction stress, enough so that the terrain fractures into a honeycomb network of subsurface cracks.

Criss-crossed dark paths wind throughout this region. Dust devils, turbulent whirlwinds fueled by rising ground-warmed atmosphere, track across the surface, stripping the ground of bright surface dust as they go. Comparable to miniature tornadoes, they efficiently transport surface materials on Mars. Left in their passing is the darker coarse-grained soil underneath.

In this image, the sun is low on the horizon; the shadows make it easier to see the scattered rocks and boulders. Sometimes, these boulders occur in rings, the remnants of an ancient impact whose crater has since eroded to a flat surface. The boulders are left behind, illustrating where the form of the crater once stood.

Written by: Albert Ortiz and Michael Mellon  (2 September 2009)
Acquisition date
19 July 2009

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
246.1 km (153.0 miles)

Original image scale range
24.6 cm/pixel (with 1 x 1 binning) so objects ~74 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
51°, with the Sun about 39° above the horizon

Solar longitude
305.9°, Northern Winter

For non-map projected images
North azimuth:  98°
Sub-solar azimuth:  44.4°
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
map projected

RGB color
non-map projected

Black and white
map-projected   (631MB)

IRB color
map-projected   (370MB)

Black and white
map-projected  (259MB)
non-map           (413MB)

IRB color
map projected  (101MB)
non-map           (356MB)

Merged IRB
map projected  (157MB)

Merged RGB
map-projected  (175MB)

RGB color
non map           (332MB)
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products

IRB: infrared-red-blue
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

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/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.