Thu, Nov 02, 2017 - Page 6 News List

FEATURE: Scientists mine ‘star scar’ to unlock space secrets under medieval castle


Rochechouart crater custodian Pierre Poupart points to a trace of a meteorite impact in France on Oct. 17.

Photo: AFP

Since early September, the denizens of this normally hushed burg in central France have been serenaded by an industrial drill poking holes around town and pulling up cylinders of rock.

That is because Rochechouart, population 3,800, and its medieval castle are built on top of an astrobleme.

“Astrobleme — which literally means ‘star scar’ — is the name given to traces left by a major meteorite impact,” said Philippe Lambert, one of the astrogeologists trying to unlock its secrets.

This particular impact crater was made by a massive space rock that crash-landed more than 200 million years ago, and has intrigued scientists since its discovery in the 19th century.

“You have a nugget under your feet,” the famous Canadian astrophysicist Hubert Reeves said in 2011 while visiting the research project here he helped launch.

Since then, scores of scientists — geologists, paleontologists, exobiologists — from a dozen nations have submitted requests to examine the space rock up close.

Lambert — who devoted his 1977 doctoral thesis to France’s only known astrobleme — directs the International Center for Research on Impacts at Rochechouart. The center is coordinating the first-ever drilling and excavation at the site.

“About 200 million years ago — before the Jurassic period and even before the planet’s continents split apart — a 6 billion tonne meteorite about 1km in diameter crashed here,” said Pierre Poupart, who oversees a natural reserve set up around the crater. “It was traveling at about 72,000kph.”

The impact — which vaporized the meteorite — was about equivalent to several thousand Hiroshima-sized atomic bombs and almost certainly destroyed all life within a radius of about 200km. The landscape was changed forever.

The Rochechouart astrobleme is unusually close to the surface, making it easier to study.

“We are walking on it,” Lambert said. “We don’t even have to dig through a layer of dirt to reach it.”

The drilling, scheduled through this month, is to yield 20 core samples taken 1m to 120m below the surface from eight different sites across a 50 hectare area.

The 600,000 euro (US$698,670) project, funded by the French government and the EU, could be the beginning of a long adventure, Lambert said.

“There’s everything here to justify an open-air laboratory,” he added.

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