ABISMO (Automatic Bottom Inspection and Sampling Mobile) is a remotely operated underwater vehicle (ROV) built by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) for exploration of the deep sea. It is the only remaining ROV rated to 11,000-meters (after Nereus, built and operated by the Woods Hole Oceanographic Institution was lost at sea in 2014), ABISMO is intended to be the permanent replacement for Kaikō, a ROV that was lost at sea in 2003.
Between 1995 and 2003, Kaikō conducted more than 250 dives, collecting 350 biological species (including 180 different bacteria), 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 (かいれい) 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.
While the temporary replacement ROV (Kaikō7000II) 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 (Automatic Bottom Inspection and Sampling Mobile), 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 (a sampling station)
- Vehicle (a sediment probe)
- Samplers (a gravity corer or Smith Macintyre type sampler)
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 here 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 (HDTV) 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.