Earth's mantle, for comparison, holds roughly 50 to 300 ppm water, researchers said.

MSN: Scientists say parts of Mars interior are as wet as Earth's

Deep underneath your feet is a hellish stone soup, kept hot by a torrent of radiation from poisonous isotopes of uranium, thorium and potassium in the earth's superheated mantle.

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Unlike any other asteroid known today, Vesta has an iron core surrounded by layers of mantle rock and crust, similar to Earth and Mars, preliminary gravity and density measurements suggest.

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The rock is peridotite, which is one of the main rocks in the upper mantle, an area that provides a girth below the Earth's crust.

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