Jamming with the “Spiders” from Mars
NASA/JPL/University of Arizona
Jamming with the “Spiders” from Mars
ESP_055283_0985  Science Theme: Seasonal Processes
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During winter at the South Pole of Mars, a carbon dioxide ice cap covers the region and as the sun returns in the spring, “spiders” begin to emerge from the landscape.

But these aren’t actual spiders. We call it “araneiform terrain,” to describe the spider-like radiating channels that form when carbon dioxide ice below the surface heats up and releases. This is an active seasonal process we don’t see on Earth. Like dry ice on Earth, the carbon dioxide ice on Mars sublimates as it warms (changes from solid to gas) and the gas becomes trapped below the surface.

Over time the trapped carbon dioxide gas builds in pressure and is eventually strong enough to break through the ice as a jet that erupts dust. The gas is released into the atmosphere and darker dust may be deposited around the vent or transported by winds to produce streaks. The loss of the sublimated carbon dioxide leaves behind these spider-like features etched into the surface.

Written by: Jennifer Newman, Sarah Simpson, Alyssa Werynski, Livio Tornabene (audio: Tre Gibbs)  (9 July 2018)
 
Acquisition date
13 May 2018

Local Mars time:
16:43

Latitude (centered)
-81.454°

Longitude (East)
296.269°

Spacecraft altitude
246.8 km (154.2 miles)

Original image scale range
49.4 cm/pixel (with 2 x 2 binning) so objects ~148 cm across are resolved

Map projected scale
50 cm/pixel

Map projection
Polarstereographic

Emission angle:
0.4°

Phase angle:
89.2°

Solar incidence angle
89°, with the Sun about 1° above the horizon

Solar longitude
174.7°, Northern Summer

For non-map projected images
North azimuth:  109°
Sub-solar azimuth:  38.0°
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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

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.