Jan. 8 - A Japanese-led project aims to drill to the Earth's mantle, a 3,000 kilometre-thick layer of slowly deforming rock between the crust and the core. In its early stages, the $US1 billion mission would deploy a drill just 30 centimetres wide to bore into the Earth's crust to bring back the first ever samples of fresh mantle rock. Jim Drury reports.
The billion dollar project to reach the Earth's mantle is being compared to the Apollo Moon missions. The Japanese-led effort will drill down six kilometres beneath the seafloor, passing through the Earth's crust until it reaches the mantle, which has never been breached before. Project co-leader Damon Teagle says that if successful, the mission could explain the origins and evolution of Earth itself. SOUNDBITE (English) DAMON TEAGLE, PROFESSOR OF GEOCHEMISTRY AT UNIVERSITY OF SOUTHAMPTON, SAYING: "We use what is known as a rotary coring bit, which is adapted from the oil industry that is used for drilling very hard formations......They make a hole that if things are going well is about 30 centimetres across and then would actually grind out a stump of core that's about six centimetres wide.....if we have the core then we can do chemical and physical experiments on the rocks and minerals that we collect." The mantle is a 3,000 kilometre-thick layer of slowly deforming rock between the Earth's crust and its core. Despite forming up to 68 percent of the Earth's mass, its chemistry and composition remains a mystery. Japanese-funded deep-sea drilling vessel Chikyu is likely to be centrestage. It's already set a world-record for the deepest hole in scientific ocean drilling history. Intensive geophysical observations of the sea floor are first needed, to help the team decide where to bore. Fresh rock sample should explain how much water, CO2, and carbon is in the mantle, and how it evolved over history. Recent discoveries of life forms found deep in the ocean crust have encouraged hopes for similar discoveries in the mantle itself. SOUNDBITE (English) DAMON TEAGLE, PROFESSOR OF GEOCHEMISTRY AT UNIVERSITY OF SOUTHAMPTON, SAYING: "One could imagine that if we had a fault zone that goes very deeply through the ocean crust, where's there's cold seawater penetrating deeply into the ocean crust, that perhaps we have life at very great depths in the ocean crust and possibly, and I say possibly, maybe even into the upper mantle." The project is still in its infancy, with more funding needed before drilling can go ahead. Even then, the drilling process itself could take years with current drill tips lasting only 60 hours before needing replacement. Teagle however, remains hopeful that technological advances will improve the team's chances by the time they're ready to start at the end of the decade.