Researchers say life on Mars may have had a better chance underground

From Engadget - December 27, 2017

"Given how little we understand about the origin of life on Earth, it makes sense to adopt a broader plan to seek signs of life," say the paper's authors. And they suggest going below the planet's surface, looking in areas that may have hosted hydrothermal systems. "Mars is not Earth," say the researchers, "We must recognize that our entire perspective on how life has evolved and how evidence of life is preserved is coloured by the fact that we live on a planet where photosynthesis evolved."

By the time Earth saw photosynthesis, Mars had been a cold, atmosphere-less planet for about a billion years. Because Mars is so much less massive than Earth, its core cooled faster, leading to a loss of the planet's magnetic field. So around four billion years ago, the planet lost most of its atmosphere and, therefore, its protection from radiation and solar winds. Thus, if Mars had developed life on its surface, it needed to have done that about a billion years earlier than Earth, which is unlikely. But subsurface life may have had a chance. "Mars may have been cold, arid, oxidizing and generally inhospitable at the surface for much of its history; however, hydrothermal conditions in the near surface or subsurface might have been considerably more clement," said the researchers.


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