Despite the fact that it likely contains water and a rocky core, that water is almost certainly in the form of steam or a supercritical fluid.

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The water leak occurred in thousands of tubes that carry heated water from the reactor core through the plant's steam generators.

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During this violent time, much of the debris would have resembled comets - dirty snowballs thought to be mostly slushy water surrounding a rocky core - slamming into Earth at velocities greater than 25 km per second (16 miles per second).

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