A giant meteorite boiled the oceans 3.2 billion years ago, but provided a 'fertilizer bomb' for life

A massive space rock, estimated to be the size of four Mount Everests, slammed into Earth more than 3 billion years ago — and the impact could have been unexpectedly beneficial for the earliest forms of life on our planet, according to new research.

A massive space rock, estimated to be the size of four Mount Everests, slammed into Earth more than 3 billion years ago — and the impact could have been unexpectedly beneficial for the earliest forms of life on our planet, according to new research.

Typically, when a large space rock crashes into Earth, the impacts are associated with catastrophic devastation, as in the case of the demise of the dinosaurs 66 million years ago, when a roughly 6.2-mile-wide (10-kilometre) asteroid crashed off the coast of the Yucatan Peninsula in what’s now Mexico.

But Earth was young and a very different place when the S2 meteorite, estimated to have 50 to 200 times more mass than the dinosaur extinction-triggering Chicxulub asteroid, collided with the planet 3.26 billion years ago, according to Nadja Drabon, assistant professor of Earth and planetary sciences at Harvard University. She is also lead author of a new study describing the S2 impact and what followed in its aftermath that published Monday in the journal Proceedings of the National Academy of Sciences.

“No complex life had formed yet, and only single-celled life was present in the form of bacteria and archaea,” Drabon wrote in an email. “The oceans likely contained some life, but not as much as today in part due to a lack of nutrients. Some people even describe the Archean oceans as ‘biological deserts.’ The Archean Earth was a water world with few islands sticking out. It would have been a curious sight, as the oceans were probably green in color from iron-rich deep waters.”

When the S2 meteorite hit, global chaos ensued — but the impact also stirred up ingredients that might have enriched bacterial life, Drabon said. The new findings could change the way scientists understand how Earth and its fledgling life responded to bombardment from space rocks not long after the planet formed.

Early in Earth’s history, space rocks frequently hit the young planet. It is estimated that “giant impactors,” greater than 6.2 miles (10 kilometres) across, pummeled the planet at least every 15 million years, according to the study authors, meaning that at least 16 giant meteorites hit Earth during the Archean Eon, which lasted from 4 billion to 2.5 billion years ago.

But the fallout of those impact events isn’t well understood. And given Earth’s ever-changing geology, in which massive craters are covered over by volcanic activity and the movement of tectonic plates, the evidence of what happened millions of years ago is hard to find.