抄録
The plan for building a new scientific deep-sea drilling vessel in Japan started more than 10 years ago. JAMSTEC (Japan Agency for Marine-Earth Science and Technology) took leadership for this project and after numerous domestic and international meetings and workshops, the construction started April, 2001 and the launching ceremony was conducted January, 2002 at Tamano Shipyard of Mitsui Shipbuilding Co.. Then the ship moved to Nagasaki for further outfitting and is under the final phase of commissioning for its various equipments.
Chikyu was designed to drill deep, deeper than anybody has done before in the deep sea floor. The initial target was set to drill 7,000m from 2,500m-deep seafloor and in the second phase it tried to drill 7,000m from 4,000m-deep seafloor. In order to ensure borehole stability and cleaning of rock cuttings, heavy mud circulation has to be maintained from the ship to the front end of drilling bit. Deployment of riser pipes that enable the confined circulation of heavy mud is the key technology of Chikyu. The ship is required to stay stationary for a long time at sea against wind, wave and current. This stability is achieved by installation of computer-controlled powerful six thrusters with unique ability of 360 degrees screw-axis rotation. Robotic and automated drill pipe handling system ensures safe working environment.
Chikyu houses wonderful scientific research facilities. Four-storied laboratory space with array of advanced equipments welcomes 50 scientists and technical support staff. With synergy of state-of-the-art technology and enthusiasm of researchers and engineers, Chikyu challenges to the depth where deep unexplored biosphere exists, the mantle rocks gradually move, strain energy for mega-earthquake responsible for huge tsunami is accumulated and hidden records of the past history of the Earth are archived.
After the delivery in July this year, the Center for Deep Earth Exploration of JAMSTEC will be responsible for the operation of the ship. Current plan is after two years of the test and training phase mostly at the offshore of Northeastern Japan, Chikyu will be introduced to IODP (Integrated Ocean Drilling Program) in late 2007. The voyage of Chikyu, seeking for a new frontier of science, technology and international collaboration is about to begin.
