Lunar crater offers clues to impact that killed the dinosaurs

New studies of the exquisitely preserved Schrödinger crater on the Moon are helping to further our understanding of the Chicxulub crater on Earth – ground zero for the asteroid impact that exterminated the dinosaurs.

Schrodinger Crater
The Moon’s 320 km (200 mile) diameter Schrödinger basin is the best preserved impact basin of its size. It has a 2.5 km (1.5 mile) high peak ring is 150 km (nearly 100 miles) in diameter. Image credit: NASA Scientific Visualization Studio (NASA SVS).

Billions of years ago, our Solar System was a very chaotic place. During an event dubbed the “Late Heavy Bombardment”, the terrestrial planets were frequently pelted with asteroids and comets. One of these impacts 3.8 billion years ago created the Schrödinger crater on the Moon – a 300 km (100 mile) wide basin that boasts a ring of mountains at its centre called a peak ring.

After the bombardment ceased, asteroids still occasionally wreaked havoc in the inner Solar System and one of these created a similar crater on the Earth. This is the Chicxulub crater, and 66 million years later it has become buried under hundreds of metres of rocks and sediments. In order to better understand the dinosaur-killing impact, a new study has been performed of its twin crater on the Moon.

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David Kring of the Universities Space Research Association, and colleagues, used the Chandrayaan-1 and Lunar Reconnaissance Orbiter spacecraft to create a map of the minerals present in the peak ring of the Schrödinger crater. By combining this new data with computer simulations, the scientists were able to decipher the most likely way that the crater was formed.

In the first moments after the impact, material from beneath the surface of the Moon was uplifted at the centre of the crater to a height of 20 km (12 miles) above the surface. In a smaller crater, this material would collapse back onto itself to become a central peak, but due to the amount of material thrown up by the Schrödinger impact, the uplift became unstable and instead flowed outwards to form the peak ring. The final height of the mountains in the centre of the crater is 2.5 km (1.5 miles).

Crater formation
A diagram showing how an asteroid impact formed the features seen in Schrödinger Crater. Image credit: V. Altounian/Science

The Chicxulub crater on Earth would have had a similar formation process, although the stronger gravity of the Earth makes it slightly less dramatic than its lunar counterpart. “The lower gravity of the Moon amplifies the topography of an impact basin,” Kring tells Skymania News.

“Thus, while the peak ring of the Schrödinger basin rises up to 2.5 km (1.5 miles) above the basin floor, the peak ring of the Chicxulub basin probably only rises a few hundred metres above the basin floor. Deeper impact basins and higher peak rings are more stable on the Moon than on Earth.”

The study also revealed that the rocks that now make up the peak ring of the Schrödinger crater were excavated from almost 30 km (nearly 20 miles) below the lunar surface during the impact. As the Chicxulub crater is smaller than Schrödinger, the peak ring rocks come from shallower depths of around 14 km (9 miles) beneath the Earth’s surface.

Boreholes of the peak ring of Chicxulub were drilled earlier this year in order to further study the infamous impact – the first time that peak ring rocks on Earth have been sampled – and analysis of the rocks has just begun. “Those studies will determine if the Schrödinger model is correct or not,” adds Kring.

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By Amanda Doyle

I am an astrophysics postdoctoral research assistant at the University of Warwick. I obtained my PhD from Keele University in 2014 and my thesis title was "Spectral analyses of solar-like stars". My research involves refining stellar parameters with the aim of improving our understanding of both stars and planets. I completed my masters in astronomy at Swinburne University of Technology via the Swinburne Astronomy Online programme in 2010, and I obtained my degree in physics with astronomy from Dublin City University in 2008. When I'm not doing research, I like to write about all aspects of astronomy. I am a freelance science writer and I contribute to Astronomy Now, NASA's Astrobiology Magazine, BBC Sky at Night magazine, Skymania News, and Sen. I am also the editor of Popular Astronomy magazine.

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