Martian History: Weathering a new notion
By Ron Cowen
A frigid desert transformed, now and again, into hell. That’s the view of ancient Mars just proposed by a team of planetary scientists, who suspect that intermittent impacts by huge asteroids and comets some 3.5 billion years ago profoundly influenced the planet’s personality.
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Those massive bodies may have melted surface and underground deposits of ice, vaporized debris that then fell out of the sky as a global shower of molten rock, and generated a torrent of scalding rain lasting for decades or possibly centuries. The hot rain would have carved and filled the channels and tributary-like structures seen on Mars today.