At first glance, a big asteroid or comet strike is bad. It creates heat that cooks anything within hundreds of miles and the blast wave carried by air, water, and rock to all corners of the globe does the rest. It even kicks up huge amounts of material so high that the world endures a rain of molten rock for days afterward, clouds of steam and dust block out the sun for years. But somehow, in the hellish days of the late Hadean or early Archean, when monster strikes happened a lot, life or something like it first arose and managed to hang on. How might that happen?
Scientists don’t fully understand how organisms survived Earth’s early and violent history, when asteroids and comets regularly pummeled the planet’s surface. Chicxulub’s peak rings show that the impact deformed the peak ring rocks and made them more porous and less dense than expected, creating a nutrient-rich home for simple organisms.
A big strike would certainly fracture the underlying bedrock for miles around, incandescent gas cooking out of the congealing magma left behind might further riddle it with frothy air pockets. All those things would make that rock way more porous to water while still providing some protection from the violence outside the rocky walls, and where water goes, we believe life often follows.
Whatever the reason, the hit marking the demise of most dinosaurs much later, at the end of the Cretaceous, certainly did hairy mammals like us a big favor. We sure wouldn’t be dining on stuffed and roasted dinosaur this holiday season had it missed. In fact, some Jurassic turkey’s feathered progeny would probably be eating small primate-like mammals to this day, without the big one that struck 66 million years ago.