Enigmatic Terrain in Hellas Basin
Enigmatic Terrain in Hellas Basin
PSP_009548_1420  Science Theme: Glacial/Periglacial Processes
Hellas Planitia is the low-lying plain on the floor of the Hellas Basin, an ancient impact crater over 2000 kilometers wide. This basin includes the lowest point on the surface of Mars.

A variety of unusual landforms occur on the floor of the basin due to the low elevation. One hypothesis is that Hellas may once have held lakes or seas, possibly with thick ice that might account for some of these features.

This image shows a small portion of western Hellas, in a region of enigmatic ridges. These ridges form an intricate pattern, enclosing kilometer-wide depressions. These strange features are still not well-understood; one possibility is that they formed in lake-bottom sediments when ice covering the lake touched bottom and shoved wet, loose material to the side. This HiRISE image reveals that the ridges contain many boulders; sediments deposited on the bottom of a lake might be fine-grained, although they may have hardened to rock later. The image also shows lineations, probably outcropping layers, running between the large ridges.

Because the resolution of HiRISE images is sufficient to see details such as the abundance of boulders and the presence of thin sedimentary layers, images of this and other poorly-understood terrains will be important in interpreting the geological and climatological history of Mars.

This observation is part of a stereo pair along with PSP_007834_1420.

Written by: Colin Dundas  (1 October 2008)

This is a stereo pair with PSP_007834_1420.
Acquisition date
09 August 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
258.6 km (160.7 miles)

Original image scale range
56.0 cm/pixel (with 2 x 2 binning) so objects ~168 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
81°, with the Sun about 9° above the horizon

Solar longitude
110.3°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  49.1°
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IRB color
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Merged IRB
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IRB color
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Black and white
map-projected  (154MB)
non-map           (188MB)

IRB color
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non-map           (150MB)

Merged IRB
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Merged RGB
map-projected  (352MB)

RGB color
non map           (135MB)
Map-projected, reduced-resolution
Full resolution JP2 download
Anaglyph details page

B&W label
Color label
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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’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.