If Mars evolved from a warm, wet, and biologically active planet to the cold desert conditions we observe today, then the last remnants of life would certainly have adapted to extreme tundra-like conditions. Such adaptation might take the form of an ability to thrive in occasional summer meltwater pools, or even the ability to subtly modify its environment to encourage the formation and persistence of such pools. Surprisingly, recent evidence of ubiquitous gullies and seeps at high latitudes suggest that such seasonal melting may have persisted even to the present day. Calculations presented here give additional credence to that suggestion by demonstrating that water is sufficiently metastable to form seasonally recurring meltwater pools under thin crusts of ice on present-day Mars. Moreover, the simplest of biological mechanisms, by affecting evaporative cooling rates and emissivity, could both encourage and prolong the lifetime of such pools.
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