Well into old age he could be spotted, in bright red parka and with frozen beard, lying full-length on the Antarctic sandstone to snap some tiny life-containing fissure in the rocks.

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Jesalva said he was in the group that spent the night on the picturesque mountain, known for its almost-perfect cone, when the volcano rumbled back to life early in the morning and rocks "as big as a living room" came raining down on them.

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Yet, some of the most promising locations to search for ancient life on Mars are places where water may have been in contact with volcanic rocks, ancient hydrothermal systems where conditions may have been conducive to life.

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Around midday, we arrived a few hundred yards below the glacier, on what seemed like a Martian plateau gray sand, strange rocks, no evidence of sentient life.

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Right here on Earth, surprisingly hardy life-forms have been found inside hot underground rocks, around scalding volcanic vents at the bottom of the ocean, in desiccated Antarctic valleys and deep beneath polar ice.

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And beyond that, trying to keep a connection with the rest of life, too -- the birds, the bees, the rocks, things like that.

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If there is life on such a planet, microscopic forms of it will probably live deep inside rocks, as they do on earth.

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The dog-sized bot, only 73 pounds (33 kilograms), will look for direct evidence of existing life, whether combing the Martian atmosphere for methane, a possible biological byproduct, or checking rocks for a form of carbon favored by cells.

CNN: Race to Mars begins a distant search for life