Chikyū
Chikyū is a Japanese scientific drilling ship built for the Integrated Ocean Drilling Program. The vessel is designed to ultimately drill beneath the seabed, where the Earth's crust is much thinner, and into the Earth's mantle, deeper than any other hole drilled in the ocean thus far.
While the planned depth of the hole is significantly less than the Russian Kola Superdeep Borehole, the scientific results are expected to be much more interesting since the regions targeted by Chikyū include some of the most seismically active regions of the world. Other deep holes have been drilled by the drill ship JOIDES Resolution during the Deep Sea Drilling Project and the Ocean Drilling Program.
Operation
The Japanese part of the IODP program is called Chikyū Hakken, Japanese for "Earth Discovery". Chikyū is operated by the Centre for Deep Earth Research, a subdivision of the Japan Agency for Marine-Earth Science and Technology. JAMSTEC also operates the DSV Shinkai, Earth Simulator supercomputer and other marine scientific research projects. CDEX is responsible for the services to support activities including on-board staffing, data management for core samples and logging; implements engineering site surveys; and conducts engineering developments. CDEX contracts with the Mantle Quest Japan Company for the navigation of the ship.The Chikyū Hakken program is part of an international scientific collaborative effort with scientists from the United States, ECORD, a consortium consisting of several European countries and Canada, China, South Korea, Australia and New Zealand, and India.
Design
D/V Chikyū was built by the Mitsui Engineering & Shipbuilding and launched on 18 January 2002 in Nagasaki, Nagasaki. The ship was outfitted by the Mitsubishi Heavy Industries and delivered to JAMSTEC on 29 July 2005.The hull of the ship is long, in width, high, and has an approximate gross tonnage of about. The ship has a draft of and a maximum cruising speed of. The amidships derrick is above sea level, and the top drive has a lifting capacity of. Its complement of 150 crew are divided between 100 operators and 50 science personnel, with at sea crew changes handled by helicopter transfer.
Key innovations include a GPS system and six adjustable computer controlled azimuth thrusters that enable precise positioning to maintain a stable platform during deep water drilling. The maximum drilling water depth for riser drilling is and can support a drill string up to long.
The helipad can serve very large helicopters transporting as many as 30 persons per landing.
History
The D/V Chikyū was built for deep-sea geological scientific research, which now includes not only research of earthquake-generating zones in the Earth's crust but also hydrothermal vents and subsea methane hydrate research.On 16 November 2007 Chikyū began drilling the transect as planned, reaching at the site of a future deep subsea floor observatory. The first stage of four NanTroSEIZE Stages was completed in February 2008. The whole project was envisioned to be completed by 2012.
The ship was damaged by the 2011 Tōhoku earthquake and tsunami on 11 March 2011. The ship was moored in the port of Hachinohe, Aomori. The tsunami wave pushed the Chikyu over the pier and the vessel sustained some damage. One of the six thrusters, No.5, was damaged and a hole was made in the bottom. Local preliminary school children who were visiting the ship at the time of the earthquake spent one night on board and were rescued by Japan Self-Defense Forces helicopters next day. The ship was repaired at a dock in Yokohama and returned to service in June 2011.
In January 2026, Chikyū will be participating in seabed mining tests off the coast of Minamitorishima, the easternmost island in Japan. Initial tests seek to process approximately 35 tonnes of material. Each tonne will contain roughly 2 kilos of rare earth metals. If successful, these technologies will increase Japanese access to rare-earth metals