Between 1995 and 2003, Kaikō conducted more than 250 dives, collecting 350 biological species, some of which could prove to be useful in medical and industrial applications. Kaikō reached a maximum depth of 10,911.4 meters at the Challenger Deep on 24 March 1995, during its initial sea trials. Kaikō returned to Challenger Deep in February 1996, this time reaching a maximum depth of 10,898 meters. Kaikō made its last visit to Challenger Deep in May 1998. On 29 May 2003, Kaikō was lost at sea off the coast of Shikoku Island during Typhoon Chan-Hom, when a steel secondary cable connecting it to its launcher at the ocean surface broke. In May 2004, JAMSTEC resumed its research operations, using a converted ROV as its vehicle. This ROV, formerly known as UROV 7K, was rechristened Kaikō7000II. The 7000 designation indicates that this vessel is rated for diving to a maximum depth of 7,000 meters.
RV ''Kairei''
RV Kairei is a deep sea research vessel that served as the support ship for Kaikō, and for its replacement ROV, Kaikō7000II. It now serves as the support ship for ABISMO. Kairei uses ABISMO to conduct surveys and observations of oceanic plateaus, abyssal plains, oceanic basins, submarine volcanoes, hydrothermal vents, oceanic trenches and other underwater terrain features to a maximum depth of 11,000 meters. Kairei also conducts surveys of the structure of deep sub-bottoms with complicated geographical shapes in subduction zones using its on-board multi-channel reflection survey system.
Development of ''ABISMO''
While the temporary replacement ROV has a remarkable performance record, it is only rated to 7,000 meters and cannot reach the deepest oceanic trenches. For this reason, JAMSTEC engineers began work on a new 11,000-meter class of ROV in April 2005. The project is called ABISMO, which translates to abyss in Spanish and Portuguese. Like Kaikō, ABISMO consists of 4 major parts:
electronic instruments aboard RV Kairei, the support ship
Launcher
Vehicle
Samplers
Except for the sampler and the smaller size of the ROV itself, the system configuration is the same as for Kaikō. The launcher launches and recovers the ROV along with its sampler. Click to see a photograph of ABISMO and its launcher, as well as RV Kairei, the support ship. The lower part of the launcher is constructed of a stainless steel framework, within which the vehicle is stored. Pressure hulls for electronic devices, a winch, a secondary cable drum and two electric transformers are located in the upper part of the launcher. The samplers include a gravity core sampler and a bottom grab sampler. There is also a docking system and an acoustic positioning system in the lower part of the launcher. The vehicle is hung in the launcher by the docking system. When the system detaches it and the cable drum feeds the secondary cable, the vehicle can dive down, and its position is measured by the acoustic positioning system. The position of the launcher is measured by RV Kairei, the support ship. The launcher also has a high-definition television camera with pan and tilt functions. Initial sea trials of ABISMO were conducted in 2007. The craft successfully reached a planned depth of 9,760-meters, the deepest part of Izu-Ogasawara Trench, where it collected core samples of sediment from the seabed. Plans are underway for a mission to the Challenger Deep. In June 2008, the Japan Agency for Marine-Earth Science and Technology deployed the 4,517-ton Deep Sea Research Vessel Kairei to the area of Guam for cruise KR08-05 Leg 1 and Leg 2. On 1–3 June 2008, during Leg 1, the Japanese robotic deep-sea probe ABISMO on dives 11-13 almost reached the bottom about east of the Challenger Deep: "Unfortunately, we were unable to dive to the sea floor because the legacy primary cable of the Kaiko system was a little bit short. The 2-m long gravity core sampler was dropped in free fall, and sediment samples of 1.6m length were obtained. Twelve bottles of water samples were also obtained at various depths..." ABISMO's dive #14 was into the TOTO caldera, about 60 nmi northeast of the deepest waters of the central basin of the Challenger Deep, where they obtained videos of the hydrothermal plume. Upon successful testing to, JAMSTEC’ ROV ABISMO became, briefly, the only full-ocean-depth rated ROV in existence. On 31 May 2009, the ABISMO was joined by the Woods Hole Oceanographic Institution's HROV Nereus as the only two operational full ocean depth capable remotely operated vehicles in existence. During the ROV ABISMO's deepest sea trails dive its manometer measured a depth of ± in “Area 1”. Leg 2, under chief scientist Takashi Murashima, operated at the Challenger Deep June 8–9, 2008, testing JAMSTEC's new full ocean depth “Free Fall Mooring System,” i.e. a lander. The lander was successfully tested twice to depth, taking video images and sediment samplings at, in the central basin of the Challenger Deep.
