Catalyst: Sept 5

Tonight on Catalyst Professor Sean Gulick and Professor Joanna Morgan present “The Day the Dinosaurs Died” as they lead an expedition at the Chicxulub asteroid impact crater, beneath the Gulf of Mexico.

An international group of world-renowned scientists are on a quest to uncover the secrets of the most significant day in our planet’s history: the day that killed the dinosaurs. 66 million years ago an asteroid the size of London hit the planet. How this resulted in the extinction of dinosaurs is a mystery that Geologists Sean Guillick and Jo Morgan have set out to answer. They are co-leaders of an expedition to drill deep into the Chicxulub asteroid impact crater, beneath the Gulf of Mexico.

This ‘Super-Crater’, twenty miles deep and one hundred miles wide contains rocks at its centre that will provide clues to what happened. As the team drill down, 1500 metres into the seabed, they travel back through time extracting solid cores of rock formed on the day of impact.

At a laboratory in Bremen the extracted cores are forensically analysed and used to calculate the force of the impact involved in forming this crater. Anything caught up in the blast zone would have been incinerated – but how was the asteroid impact so lethal to life right across the planet?
2400 miles from the impact zone, in modern day New Jersey, Professor Ken Lacovara is digging into the ancient sands at the bottom of a quarry where he’s unearthed a scene of carnage. Over 20,000 fossils including crocodiles, mosasaurs (marine dinosaurs), and the broken femurs of terrestrial giants. It’s a chaotic jumble of creatures that lived in completely different environments but whom fled and died together. These are the only fossils found anywhere in the world from the exact moment of the disaster itself. This ‘mass death assemblage’ is evidence of a catastrophic chain of events – huge Tsunami’s and devastating wildfires triggered by the impact.

Scientists have long believed that the impact blew so much debris into the atmosphere that the following years were marked by a ‘nuclear winter’. Now, the team has unearthed new data that will finally reveal exactly what triggered this cold world of darkness. But, it’s not what’s in the rock cores; it’s what’s missing.

The bedrock in Mexico should be dense in sulphur-rich Gypsum, but the scientist can find no traces in the rock cores from the crater. This means the impact blasted the Gypsum up into the atmosphere, where it turned into sulphur – gasses that block out sunlight. As these gases enveloped the world a ‘nuclear winter’ ensued lasting up to 2 years. Temperatures on the ground plummeted and photosynthesis was stopped.

Impact, tsunamis, wildfires – and now nuclear winter: the heat-loving dinosaurs were doomed. However, mammals did survive and they evolved to take over the planet.

Hosts: Professor Sean Gulick is an eminent geophysicist who has conducted expeditions all over the world, from Alaska to Antarctica. As one of the two Co-Chief Scientists of the Chicxulub Impact Expedition, Sean is leading the scientific team as they drill into the crater’s peak ring for the very first time.

Professor Joanna Morgan is the Co-Chief Scientist and instigator of this project, who fought for twenty years to gain permission (and funding) to drill this impact crater. Finally, able to look at the material that sat at the heart, and bore the brunt, of the initial impact, Jo will be building, refining – and possibly re-thinking – models that track what occurred in the moment the asteroid met the earth and immediately after, the forces involved and how these enigmatic peak rings were formed. Jo is also a Professor of Geosciences at Imperial College, University of London.
Featuring Australian academics…

Dr Jasmina Lazendic-Galloway, Astrophysicist, Monash University.

Steve Salisbury, Paleontologist, University of Queensland. Stephen Poropat, Paleontologist, Swinburne University.

Tuesday 5 September, 8.30pm on ABC.

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