<p>This is Not the Hydrothermal Deposit You’re Looking For — A hotspot for exploration on Mars centers on areas that were once, or are currently, next to a significant source of heat such as volcanoes. Martian volcanoes have not been active for the last couple million years, but beneath the shifting sands and dust of the Red Planet we find old lava flows frozen in time. 
</p><p>These ancient lava flows may have provided a source of heat, along with liquid water or subsurface ice, to generate an environment conducive for the development of ancient life. Geological evidence for hot water interacting with rock is what we mean by hydrothermal: sites with these conditions are very difficult to identify from orbit. 
</p><p>NASA/JPL/University of Arizona (289 km above the surface, less than 1 km across)
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Source: <a rel="nofollow" class="external text" href="https://www.uahirise.org/ESP_055282_2125">www.uahirise.org/ESP_055282_2125</a>
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/71688597@N05">UAHiRISE (NASA)</a>
2018-07-11 16:56
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/uahirise-mars/29786050488/">ESP_055282_2125</a>