Only on Mars
NASA/JPL-Caltech/UArizona
Only on Mars
ESP_028910_0985  Science Theme: Seasonal Processes
The South Polar terrain of Mars has a landscape unlike anywhere on Earth. In this scene groups of radially-organized channels, informally called "spiders" or more formally "araneiform terrain," are visible in rows.

Spiders come in many sizes and are thought to be formed by erosion in the Martian spring. In the wintertime a seasonal polar cap composed of dry ice covers the polar region. In the spring, the gas escaping from under the ice erodes the channels in the surface. As the gas escapes into the atmosphere it deposits the material it is carrying, forming the dark splotches and fans we see in this image.



Written by: Candy Hansen (audio by Tre Gibbs)  (14 November 2012)

This is a stereo pair with ESP_028911_0985.
 
Acquisition date
26 September 2012

Local Mars time
16:10

Latitude (centered)
-81.461°

Longitude (East)
295.800°

Spacecraft altitude
247.8 km (154.0 miles)

Original image scale range
52.4 cm/pixel (with 2 x 2 binning) so objects ~157 cm across are resolved

Map projected scale
50 cm/pixel

Map projection
Polarstereographic

Emission angle
20.0°

Phase angle
103.0°

Solar incidence angle
87°, with the Sun about 3° above the horizon

Solar longitude
178.0°, Northern Summer

For non-map projected images
North azimuth:  99°
Sub-solar azimuth:  36.8°
JPEG
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

JP2
Black and white
map-projected   (258MB)

IRB color
map-projected   (159MB)

JP2 EXTRAS
Black and white
map-projected  (157MB)
non-map           (147MB)

IRB color
map projected  (73MB)
non-map           (150MB)

Merged IRB
map projected  (261MB)

Merged RGB
map-projected  (232MB)

RGB color
non map           (138MB)
ANAGLYPHS
Map-projected, reduced-resolution
Full resolution JP2 download
Anaglyph details page

ADDITIONAL INFORMATION
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products
HiView

NB
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

USAGE POLICY
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-Caltech/UArizona

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.