WorldWide Drilling Resource

18 FEBRUARY 2019 WorldWide Drilling Resource ® Drilling into a “Star Scar” to Unlock Mysteries of Space Compiled by Caleb Whitaker, Associate Editor, WorldWide Drilling Resource ® The city of Rochechouart, France, and its medieval castle were built on top of a major meteorite impact called an astrobleme, which literally means “star scar”. Before the planet's continents split apart about 200 million years ago, a six billion-ton mete- orite crashed down at the site. It was traveling at about 45,000 miles per hour, and was vaporized during the impact, which would have been roughly equivalent to several thousand Hiroshima-sized atomic bombs. This probably would have destroyed all life within a radius of 125 miles, leaving the landscape changed forever. The Rochechouart astrobleme is the only one in France, making it a geological treasure. Scientists from a dozen countries have submitted requests to examine the site of the impact up close. The impact has lost its topographic expression and only the center of the object is preserved. An assembly of debris and products resulting from the fusion caused by the impact are the only traces observed today on the surface. However, traces of the asteroid which lie belowground are unusually close to the surface, making it easier to study. This means it’s essential to carry out core drilling to understand the mineralogical and chemical transformations of the rocks in depth. In 2017, the International Center for Research on Impacts at Rochechouart (CIRIR) coordinated the first-ever drilling and excavation at the site. The project, funded by the French state and the European Union, could be the beginning of a long adventure. Scientists cored 20 samples from various depths up to nearly 400 feet below the surface at eight different sites. Once the Rochechouart rock cores were secured, tagged, and archived, they were made available to researchers around the world. More than 60 experts were expected to examine rock cores on-site in a laboratory. These cores will allow scientists to deepen their knowledge of the site. Scientists would like to see the site become a natural laboratory benefiting national and international research. Some hope to unravel remaining mys- teries about how such meteorites form, as well as information about their evolution in space. Others are on the hunt for chemical traces capable of shedding light on which raw ingredients essential for life on earth came from space. Geologists are curious about how cataclysmic impacts might have released water held within rock formations, while palaeobiologists are looking at how an event which could massively destroy life, also creates conditions for new lifeforms to emerge. Photos courtesy of CIRIR/Philippe Lambert. A rock core from Rochechouart. ENV