A Journey Closer to Center of Earth

The Chikyu is studded with superlatives. Completed last year, the ship houses the world’s biggest deep-sea drill, sports a high-tech floating laboratory and boasts a $500-million price tag.

The Japanese boat has an ambitious agenda to match: to uncover the secrets of climate change, find microbes that throw light on the origin of life, and explore the causes of earthquakes.

The 210-yard ship went on its first major test run in November, drilling deep into the ocean floor off northern Japan for specimens that scientists say can yield historical information on everything from volcano cycles to global warming.

“The contributions from this are actually immense,” said Daniel Curewitz, a structural geologist who supervises the ship’s lab. He pointed to long tubes of deep-sea sediment: “Each one of these cores is a tape recorder.”

The key to the project is the Chikyu’s mammoth drill, which operators say is capable of boring nearly 4 1/2 miles into the ocean floor. By contrast, the deepest the U.S. drilling vessel, the 20-year-old Joides Resolution, has bored is a 1.3-mile hole.

“Beyond 2,000 meters [1.2 miles], we will be opening a new frontier in earth sciences,” declared Asahiko Taira, a U.S.-educated geologist and director general of the Center for Deep Earth Exploration, under the Japan Agency for Marine-Earth Science and Technology.

The drill can bore to greater depths through the innovation of the “riser pipe,” which envelopes the drill above the ocean floor and sucks debris out, making it possible to go deeper.

Chikyu -- which means Earth in Japanese -- also has a dynamic positioning system that can keep the ship fixed in an area with a 30-yard diameter, avoiding a drift that would bend the drill as it drives into the seabed.

Curewitz said samples taken from Earth’s mantle -- a place not yet reached -- could yield a wealth of scientific information.

Core samples can be analyzed at the floating laboratory, but the Japan agency also has established a research institute in Kochi, southwestern Japan, for more in-depth examination.

Scientists hope to learn more about a variety of subjects, ranging from climate change over the centuries, atmospheric composition to mantle core and plate dynamics, marine ecosystems and extremophiles, animals that can exist under conditions of extreme temperature or pressure.

If organisms were discovered living under the extreme heat and pressures of Earth’s mantle, for instance, scientists may get clues about how life began and evolved in the early years of the planet’s existence.

“We can get an idea for where these sediments came from, what kind of animals were living on the bottom and in the ocean at the time,” Curewitz said. “All of those things give us different ideas for ... how the climate changed over time.”

After another year of tests, the Chikyu, built by Mitsubishi Heavy Industries, will join the country’s long-cherished Japanese quest to better understand -- and perhaps even predict -- earthquakes.

Japan is one of the most quake-prone nations on Earth, sitting atop four tectonic plates. A temblor took more than 6,400 lives in the city of Kobe in 1995, and studies show about 11,000 people could die if a major quake hit Tokyo.

To meet that danger, Japan has a well-developed network of quake detection and alerts. News of a quake flashes across TV screens within a minute after it strikes. But despite decades of research and the latest technology, the ability to forecast an earthquake remains elusive.

The Chikyu’s first assignment will be in the Nankai Trough, a Pacific Ocean zone between two major tectonic plates that has produced powerful, destructive earthquakes off southwest Japan over the last 1,500 years.

Geologists hope to drill deep into the ocean floor there to the boundary between the oceanic and continental plates for the first time into what’s known as a seismogenic zone -- the flash point for quakes.

Scientists will pull up core specimens to glean crucial details, such as what kind of rock is on the plate boundary zone. Hard rock plate edges can lock against one another and then snap under pressure, while soft rock edges can slide slowly and are less likely to trigger a quake.

Researchers also plan to install monitors in the series of holes drilled by Chikyu and connect them to a cable along the ocean floor that runs to a land station, setting up a mechanism for quick detection of undersea plate movements.

Even then, the ability to predict quakes will be limited: Taira said researchers were hoping for a 30-second advance warning -- barely enough time to turn off the stove and dive under the table before disaster strikes.

Still, Taira is hopeful.

“We may be able to have a real-time warning that would save lives,” he said.