For a brief moment, those watching would have seen a hunk of space rock the size of a city hurtling Earthward at inconceivable speed. Then there was a flash of light and a release of energy like a billion atomic bombs. The force of the impact sent towering mega-tsunamis raging across the Gulf of Mexico and blew a superheated cloud of dirt, rock and dust sky high. When the cloud descended, it coated everything from the Yucatan to the Caribbean in hundreds of feet of debris. Meanwhile, the shock waves set off devastating earthquakes and volcanic eruptions around the globe — perhaps worsening a massive flood of lava that was already bubbling up from a hotspot beneath India.
Some 70 percent of the Earth’s species are thought to have died as a result of this collision, including the dinosaurs. Sixty-six million years later, the evidence of the catastrophe is still all around us. Scientists see it in the way so many species seem to vanish simultaneously from the fossil record. They see it in the thin layer of irridium-laced sediment (irridium is a rare mineral that almost exclusively comes from space) that blanketed the entire Earth.
And they see it in the truly gigantic impact crater — a bowl some 12 miles deep and more than 100 miles across — that sits just off of Mexico’s Yucatan Peninsula,
Or at least, they can picture it. The Chicxulub crater, as the site is known, is buried in sediment and hidden beneath some 1,500 feet of water. That makes it very hard to study, even though it’s ground zero of one of the worst mass extinctions in Earth’s history, one of just five times when life itself out on the planet was in danger of being snuffed.
On Thursday, if all goes according to plan, geophysicists will finally begin to drill into that infamous site, Nature reported. Over the course of the next few months, the team of American, British and Mexican scientists will extract samples of rock in search of clues to how the cataclysmic event unfolded.
“We don’t really know what this material will look like,” Jaime Urrutia-Fucugauchi, a geophysicist at the National Autonomous University of Mexico and a coordinator of the project, told Nature. “It could be a real surprise.”
The researchers’ first goal is to examine Chicxulub’s “peak ring,” the arcing chain of mountains that juts up from inside the crater floor. Though these rings appear in impact craters across the solar system, they remain somewhat enigmatic, and scientists don’t quite know how they form. Chicxulub is the only crater on Earth big enough and well-preserved enough to still have one.
Their working theory is that the Earth rebounded after the asteroid’s initial punch, according to the BBC, plummeting down and then bouncing back upward before falling in a circle around the central impact zone.
“We want to know where the rocks that make up this peak ring come from,” co-chief scientist Joanna Morgan, a geophysicist at Imperial College London, told the BBC.
“Are they from the lower, mid or upper crust? Knowing that will help us understand how large craters are formed, and that’s important for us to be able to say what was the total impact energy, and what was the total volume of rock that was excavated and put into the Earth’s stratosphere to cause the environmental damage.”
The $10 million project is the first to drill offshore at Chicxulub, according to Nature. Using a liftboat named “Myrtle” as a drilling platform (the water there is too shallow for a conventional drilling rig but propping “Myrtle” up onto three legs standing on the seafloor should do the trick), Morgan and her team will send probes through the thick mud on the gulf floor into the earth below.
The initial 500 or so meters of rock won’t say much, the researchers said. But at about 600 meters, they’ll hit the rock layer from the Palaeocene–Eocene Thermal Maximum, a period about 55 million years ago when a runaway greenhouse effect and a huge bump in global temperatures lead to the death of many species. Another 50 or so meters after that, and they’ll reach the peak ring. They hope to drill down as deep as 1,500 meters — nearly a mile beneath the ocean floor.
And the project is not only looking for signs of devastation. Researchers will also examine the rock samples from the site for ancient DNA, and it’s not unreasonable to think they’ll find it. Water from the shallow sea where the asteroid hit likely flooded through the superheated rocks after the impact, leaching out nutrients that could sustain microorganisms. By dating the new life and the rocks where they were found, they hope to determine how long it took for living things to reclaim the dead zone.
“By looking directly at ground zero, we can watch life recover,” Sean Gulick, a geophysicist at the University of Texas at Austin and the expedition’s other co-chief scientist, told Nature.
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