Gas under pressure will choose an easy escape route. In this image, the terrain is covered with a seasonal layer of dry ice.
<p>The weak spots, for gas sublimating from the bottom of the seasonal ice layer to escape, appear to be around craters, where the surface was broken and pulverized by an impact. <a rel="nofollow" class="external text" href="http://static.uahirise.org/images/2016/details/cut/ESP_046332_1040.jpg">Fans of surface material deposited on top of the seasonal ice layer show where the escape vents are.</a>
</p>
The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace &amp; Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.
NASA/JPL-Caltech/Univ. of Arizona
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