“Imagine standing on a shelf of shallow water off Cape Cod. It is a low power environment without strong currents. Then suddenly a giant tsunami appears, tearing apart the seafloor.” There is probably no better example of the destructive power of space rocks on our planet than the asteroid that wiped out the dinosaurs, along with three-quarters of the plant and animal species on Earth, some 66 million years ago.

Scientists have now discovered that a much older and larger space rock may have crashed into Earth, but it appears to have benefited life, not destroyed it. The impact occurred about 3.3 billion years ago, in the early period of the solar system when asteroid collisions were much more common.

The asteroid, called S2, is about 200 times larger than the impactor that wiped out the dinosaurs, called Chicxulub. S2 hit Earth at a time when only simple single-celled life existed on our planet, and the destruction caused by the impact off the coast of Cape Cod may have actually helped these simple life forms thrive, causing an explosion in the population of bacteria and archaea.

“We believe impact events are catastrophic for life,” team leader and Harvard University geologist Nadia Drabon said in a statement. “But what this study highlights is that these effects may have been beneficial to life, especially early on, and that these effects may have actually allowed life to develop.”

Evidence of this ancient impact was discovered by a team of scientists led by Harvard Drabon in the Barberton Greenstone Belt region of South Africa. The researchers meticulously collected rock samples, examined the rocks’ chemical composition, and analyzed the distribution of different forms, or isotopes, of carbon in them. This allowed Drabon to tell the story of what happened when S2 crashed into our planet 3 billion years ago.

The day the meteorite came

When S2 hit Earth, it would trigger a massive tsunami that would churn the ocean floor with debris and wash it into coastal areas. The immense heat created by the collision would boil the upper layers of the ocean and also heat the Earth’s atmosphere.

“Imagine standing on a shelf of shallow water off Cape Cod. “It’s a low-energy environment with no strong currents,” Drabon said. “Then all of a sudden there’s a giant tsunami tearing up the seafloor.”

An asteroid impact would have thrown debris into the atmosphere, creating a thick layer of dust covering the sun, preventing many simple life forms from converting sunlight into energy through photosynthesis. However, bacteria can survive this storm by quickly recovering from the shock. The team also believes that single-celled organisms that fed on the elements iron and phosphorus experienced a population explosion after the disaster.

Dramatic increases in the populations of certain types of single-celled life were made possible by the extraction of iron from the ocean depths and its transport to shallow waters by tsunamis. Excess phosphorus may have been created due to the erosion of land parcels and the supply of additional phosphorus to the Earth by S2 itself.

The team proposes that iron-consuming bacteria proliferate after initial exposure to S2, albeit for a relatively short period of time. This shift in favor of iron-metabolizing bacteria is one of the missing pieces of the puzzle of the earliest age of life on Earth.

This is the eighth discovery of an asteroid impact in the area where Drabon’s research was conducted. The finding was made possible in part by the intense physical work Drabon and his colleagues did while exploring mountain passes to find evidence of early rock showers that had collapsed to the ground and been preserved over time. Researchers will continue to explore this region, looking for evidence of asteroid impacts, tsunamis, and other disasters that could help us better tell the story of our beloved planet Earth.