If there ever was life on Mars—and that's a huge "if"—conditions during the planet's infancy most likely would have supported it, according to a study led by University of Arizona researchers.

Dry and extremely cold, with a tenuous , today's Mars is extremely unlikely to sustain any form of life at the surface. But 4 billion years ago, Earth's smaller, red neighbor may have been much more hospitable, according to the study, which is published in Nature Astronomy.

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