Iron volcanoes may have erupted on metal asteroids, study says

A new study suggests that volcanoes full of liquid iron may have erupted through metallic asteroids floating in space.

The research, published in the scientific journal Geophysical Research Letters, comes ahead of NASA's planned look at Pysche, the largest metallic asteroid in the solar system. UC Santa Cruz professor Francis Nimmo said he was interested in the composition of metallic asteroids and asked a team to look into how they cooled and solidified.

"One day [graduate student Jacob Abrahams] turned to me and said, 'I think these things are going to erupt,'" Nimmo said in a statement. "I'd never thought about it before, but it makes sense because you have a buoyant liquid beneath a dense crust, so the liquid wants to come up to the top."


Researchers have long believed that metallic asteroids initially started their lives as molten iron floating in space, at a time when the planets were just beginning to form. From there, they would ultimately cool, thanks to the incredibly cold temperatures of space, and solidify into the asteroid.

"In some cases, [the iron] would crystallize from the center out and wouldn't have volcanism, but some would crystallize from the top down, so you'd get a solid sheet of metal on the surface with liquid metal underneath," Nimmo added.

It's unclear what the volcanoes would look, but Abrahams said it depends on the composition of the melt.

"If it's mostly pure iron, then you would have eruptions of low-viscosity surface flows spreading out in thin sheets, so nothing like the thick, viscous lava flows you see on Hawaii," he said in the statement. "At the other extreme, if there are light elements mixed in and gases that expand rapidly, you could have explosive volcanism that might leave pits in the surface."

NASA's Psyche mission is slated for a 2022 launch date, ultimately reaching the space rock four years later.