Researchers plan to drill deep into crater left by dino-killing asteroid

Sixty-six million years ago, an asteroid the size of Manhattan slammed into Earth, leading to the extinction of the dinosaurs and most life on the planet.

Now, researchers are drilling into the Chicxulub crater — the asteroid crater that formed in the Gulf of Mexico — to peer into the lives of the creatures that survived.

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• Ocean acidification from CO2 blamed for world's worst mass extinction

CBC Radio science columnist Torah Kachur explains what they're hoping to find.

What are the researchers looking for?

Essentially, they're drilling for dinos.

The researchers are a team led by University of Texas at Austin. On April 1, they'll start a $10 million project to probe the sea floor and below.

To do that, they have a diamond-tipped drill that will spend two months drilling around the clock, about 30 kilometres offshore in the Gulf of Mexico.

We know now that's where a massive asteroid slammed into Earth, spelling doom for the dinosaurs. But lead researcher Sean Gulick said there are still a lot of unanswered questions about that cataclysmic event.

"We want to learn more about the extinction itself, about potential issues about what might have caused it, what sort of life might have come back first at ground zero of the impact," he said.

They'll also be looking for clues about what happens when Earth is struck by such a massive object, and even what possible benefits there might be to something like that — the creation of a habitat for exotic life, for example.

The plan is to drill for samples of the rock that lies 1,500 metres below the sea floor, which they hope will point to answers to these questions.

What do they expect to find in the rock cores?

The researchers expect the first 500 metres to be relatively unremarkable limestone. But beneath that is where they think they'll hit pay dirt.

Once through the limestone layer, they will take three-metre-long core samples of the earth that lies below the sea. They're looking for changes in rock type that will suggest what happens after an asteroid hits. 

More specifically, the researchers are anxious to get a glimpse at something called the peak ring. That's the rim of a crater, or the raised section that forms when an asteroid hits a planet.

There are lots of peak rings on the moon and Mars and Mercury, but most of the ones on Earth have eroded away — except the one in the Chicxulub crater. As such, it provides a unique research opportunity on our planet.

What are scientists hoping to learn by studying the peak ring?

The theory is that the peak ring is what's left over from something called the central uplift that forms during impact. Imagine throwing a rock into water: you'd see the impact, and then a column that rises up in the middle of the impact and throws ripples across the water.

Scientists think the peak ring is the ripple that doesn't travel, and instead forms a rim after rock and earth is thrown into the air during an impact. It's believed to contain granite from deep in the Earth that rose up and fell on top of younger rocks.

One of the first things researchers are interested in finding out is whether the peak ring theory holds up.

But more importantly, as the granite rocks were thrown up into the air and crashed back down onto Earth, it's believed they may have fractured and been filled with hot, mineral-rich fluids. Those rocks may have been home to all sorts of interesting life.

What kind of life would be living there?

The researchers will be collecting DNA, as well as cataloguing microfossils from the post-impact era in the cores to try to determine what actually survived the impact. That might provide clues into what caused the mass extinction.

It's now widely accepted that the dinosaurs went extinct because of the fallout of the asteroid hit. But what is it that actually suffocated the Earth, and led to 75 per cent of all species on the planet going extinct?

Scientists think there are two possibilities. One is that the asteroid caused worldwide volcanic eruptions that filled the atmosphere with poisonous gas.

The other is that the debris from the resulting natural disasters effectively coated the Earth and all the food sources.

The researchers should be able to tell from the rock cores what type of life existed right after impact. They will be looking to determine if the life back then was mostly what's called acidophiles — organisms that love high-acid environments. If so, that would mean the carbon dioxide levels likely peaked after the impact, making the oceans more acidic, and contributing to the mass extinction.

They'll also be looking for other kinds of life — microbes in particular, and ones that may be living in the cracked rocks or mineral veins from the massive impact. These just may represent the type of life that thrives after impacts, and may have been some of the earliest life on Earth, when the planet was frequently struck by asteroids.