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How computers can re-create prehistoric catastrophes talk Wednesday

Frontiers in Science public lecture series

A month ago, a small asteroid whizzed by a mere 26,000 miles from Earth, the first time astronomers detected a space rock that came so close without hitting Earth.

The dinosaurs living 65 million years ago weren't so lucky. They appear to have been wiped out by an asteroid impact that evidently struck the Yucatan Peninsula with the force of hundreds of millions of nuclear weapons.

Beginning with a public lecture Wednesday evening in Los Alamos and continuing through early May in Taos, Española, Albuquerque and Santa Fe, a Laboratory physicist will talk about how computer simulations can teach us about the Earth's cataclysmic past and the underlying processes that we see today on land, in the sea and in the atmosphere.

Galen Gisler of Thermonuclear Applications (X-2) will speak on "Calculating Extinction: The Meteor Impact That Killed the Dinosaurs," at 7:30 p.m., in the Duane W. Smith Auditorium at Los Alamos High School. Gisler's talk is the latest in the Laboratory's Frontiers in Science lecture series.

The most recent and well-known catastrophic mass extinction in Earth's fossil record is the so-called K/T boundary event, which defines the end of the Cretaceous (K) Period, when dinosaurs last ruled the Earth, and the beginning of the Tertiary (T), the age of mammals. Evidence that an asteroid caused this mass extinction include the enormous Chicxulub crater in the soft sediment of the Yucatan Peninsula, soot deposits from that geological era, deposits from tsunami in the Caribbean Sea, and a huge injection of volatile, climate-changing compounds into the atmosphere, all dated to about 65 million years ago.

"Computer simulations recreate events like this to show how the observed facts are linked to one another and to the event that produced them," Gisler said. "We make guesses about the size, speed and trajectory of the asteroid, and then we run a calculation. Comparing the calculation's results with the geological evidence helps us to refine those guesses, and in addition, improves our understanding of highly dynamic processes in Earth's crust and atmosphere."

To simulate the asteroid event, Gisler and his colleagues used a computer code from Los Alamos' Crestone project that was capable of providing dramatic details in three dimensions. The simulation required one million hours of processor time on the Laboratory's ASCI Q supercomputer.

The complete schedule for Gisler's lectures, all of which start at 7:30 p.m., is as follows:

• Los Alamos --Wednesday, Duane W. Smith Auditorium, Los Alamos High School;
• Taos -- Thursday, Taos Convention Center;
• Española -- April 21 , Center for the Arts Theater Amphitheater, Northern New Mexico Community College;
• Albuquerque - April 22, New Mexico Museum of Natural History and Science; co-sponsored by the New Mexico Museum of Natural History and Science; and
• Santa Fe -- May 6, James A. Little Theater, New Mexico School for the Deaf.

The Frontiers in Science Public Lecture Series is in an effort by Laboratory researchers to inform neighboring communities about the broad range of scientific and engineering research at the Laboratory.

More information about the series and about Gisler's talk is available at http://stb.lanl.gov/program/frontiers.shtml online.

-- Jim Danneskiold

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