NASA announcement: Metal asteroids may once have had IRON-SPEWING VOLCANOS

Those pockets would be more buoyant than the rock above them, so they’d force their way up and out, Johnson says.

If Psyche has such a rocky veneer over iron, that could explain why the asteroid appears much less dense than expected, Johnson says.

“We kept thinking, ‘It’s too wild, it can’t be right,’ ” says Professor Brandon Johnson of Brown University, of the idea of ferrovolcanism.

“But we couldn’t prove to ourselves that it wouldn’t work. Because another group came up with the same idea at the same time, it cannot be too wild.”

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