If Land of the Lost taught me anything, it’s that cool things lurk just below the surface of the earth (and Will Ferrel is the greatest actor of his generation). That’s where the Chikyu Hakken Deep Sea Drill comes in.
The Deep Sea Drilling Vessel D/V Chikyū Hakken (“Earth Discovery” aka “Godzilla-Maru”) is a Japanese scientific drilling ship completed in 2005 for the Integrated Ocean Drilling Program and is operated by the Japanese centre for Deep Earth Research. It’s designed to bore seven kilometers beneath the seabed and into the Earth’s mantle, deeper than any past ocean-drilled hole. Once into the mantle, the Chikyu will study and collect samples from the seismogenic zone, shedding light on the internal structure of the planet and how it affects the formation of Earthquakes, as well as look for the presence of undiscovered life in the Earth’s crust and deep-sea resources.
The Chikyu is 210m long, 38m wide and over 16m high. It weighs in at roughly 57,087 tons and a top speed of 12 knots. Rising 70m above the deck (100m above the water), the amidships derrick has a lifting capacity of 1250 tons and uses a 10,000m drill string – three times longer than the height of Mt Fuji. The Chikyu supports 150 crew members, including 50 science personnel with at-seas crew changes and resupplies handled via helicopter transfer. Since the Chikyu can’t move once it starts drilling, the ship is equipped with an advanced GPS system and six computer-controlled, 3.8m wide azimuth thrusters that work to counteract the effects of tides and currents, keeping the ship directly above the bore site. It also uses a riser system to negate wave action, allowing the rig to drill in waters as deep as 2500m.
The Chikyu drills at a varying rate, depending on how deep its gotten. It cuts through 15m/hr down to 1000m, 8m/hr down to 2000m, but only 3m/hr below that. Once the pipes hit 4000m, it takes approximately 6 hours to fish out and replace a worn drill bit. At those rates, the Chikyu will have to remain stationary in the sea for over a year to reach its 7000m goal.
The actual procedure for getting down there goes a little something like this: The boat positions itself above the bore site using GPS and transponders on the sea floor. The GPS also measures the external forces acting upon the boat and precisely counters them using the azimuth thrusters, preventing it from drifting more than 4.5m away. The drill string is then extended to the sea floor where it starts eating through the Earth’s crust. Every few hundred feet, a 9m rock sample is fished from the line and its chemical properties are analysed. This process continues until the team (hopefully) hits mantle somewhere 7000m down.
The Chikyu was damaged in the Japanese quake earlier this year. Though it was docked at Hachinohe, more than 250km north of Sendai, the rapid change in water level caused it to scrape bottom, snapped off one of the six thrusters, and gashed a 1.5m hole in the hull. Repairs were only recently completed at the end of June.
[IODP – Jamstec (Expedition) – Chikyu Wiki – Jamstec (Equipment) – Popular Science]
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