Kaikō ROV
Another ROV, "Kaikō7000II", served as the replacement for "Kaikō" until 2007. At that time, JAMSTEC researchers began sea trials for the permanent replacement ROV, "ABISMO" (Automatic Bottom Inspection and Sampling Mobile). "ABISMO" is currently one of only two ROVs rated to 11,000-meters (the other being "Deepsea Challenger", piloted by director James Cameron). Challenger Deep. Bathymetric data obtained during the course of the expedition (December 1872 – May 1876) of the British Royal Navy survey ship enabled scientists to draw maps, which provided a rough outline of certain major submarine terrain features, such as the edge of the continental  shelves and the Mid-Atlantic Ridge. This discontinuous set of data points was obtained by the simple technique of taking soundings by lowering long lines from the ship to the seabed. Among the many discoveries of the "Challenger" expedition was the identification of the Challenger Deep. This depression, located at the southern end of the Mariana Trench near the Mariana Islands group, is the deepest surveyed point of the World Ocean. The "Challenger" scientists made the first recordings of its depth on 23 March 1875 at station 225. The reported depth was 4,475 fathoms (8184 meters) based on two separate  soundings. On 23 January 1960, Don Walsh and Jacques Piccard were the first men to descend to the bottom of the Challenger Deep in the "Trieste" bathyscaphe. Though the initial report claimed the bathyscaphe had attained a depth of 37,800 feet, the maximum recorded depth was later calculated to be . At this depth, the water column above exerts a barometric pressure of , over one thousand times the standard atmospheric pressure at sea level. Even at this great depth and pressure, a small flounder-like fish was seen moving away from the spotlight of the bathyscaphe. Since then, only one manned  vessel has ever returned to the Challenger Deep, the Deepsea Challenger, which was piloted by director James Cameron on March 26, 2012 to the bottom of the trench. In March 1995, "Kaikō" became the second vessel ever to reach the bottom of the Challenger Deep, and the first craft to visit this location since the "Trieste" mission. The maximum depth measured on that dive was 10,911.4 meters, marking the deepest dive for an unmanned submersible to date. On 31 May 2009, "Nereus" became the third vessel to visit the bottom of the Challenger Deep, reaching a maximum recorded depth of  10,902 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. Timeline and fate of "Kaikō . In February 1996, Kaikō" returned to Challenger Deep, this time collecting sediment and microorganisms from the seabed at a depth of 10,898 meters. Among the novel organisms identified and collected was "Moritella yayanosii" and "Shewanella benthica". These two species of bacteria appear to be obligately barophilic. The optimal pressure conditions for growth of "S. benthica" is 70 Megapascals (MPa), while "M. yayanosii" grows best at 80 MPa; no growth at all was detected at pressures of less than 50 MPa with either strain. Both species appear to contain high levels of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), omega-3 fatty  acids which could prove to be useful in the treatment of hypertension and even cancer. In December 1997, "Kaikō" located the wreck of "Tsushima Maru" on the sea floor off the coast of Okinawa. "Tsushima Maru" was an unmarked Japanese passenger/cargo ship that was sunk during World War II by , a United States Navy submarine. In May 1998, "Kaikō" returned again to Challenger Deep, this time collecting specimens of "Hirondellea gigas". "Hirondellea gigas" (Birstein and Vinagradov, 1955) is a crustacean of the Uristidae family of marine amphipods. In October 1999, "Kaikō" performed a robotic mechanical operation at a depth  of 2,150 meters off the coast of Okinawa near the Ryukyu Trench, connecting measuring equipment with underwater cables on the sea floor. On this mission, another bacterial species, "Shewanella violacea", was discovered at a depth of 5,110 meters. This organism is notable for its brilliant violet-colored pigment. Certain compounds found in "S. violacea" may have applications in the cosmetics industry (development of products for lightening of skin tone) and also in the semiconductor industry (development of chemicals to be used in production of semiconductors). In late November 1999, "Kaikō" located the wreckage of H-2 No. 8, a NASDA rocket  (satellite launch system), on the sea floor at a depth of 2,900 meters off the Ogasawara Islands. H-2 flight F8 was conducted on 15 November 1999. The rocket, which was carrying a Multi-Functional Transport Satellite (MTSAT) payload, self-destructed after experiencing an engine malfunction shortly after it was launched. In August 2000, "Kaikō" discovered hydrothermal vents and their associated deep sea communities at a depth of 2,450 meters near the Central Indian Ridge. The Central Indian Ridge is a divergent tectonic plate boundary between the African Plate and the Indo-Australian Plate located in the western Indian Ocean. On  29 May 2003, "Kaikō" was lost at sea during Typhoon Chan-Hom, when a steel secondary cable connecting it to its launcher at the surface broke off the coast of Shikoku Island. In May 2004, JAMSTEC resumed its research operations, using a converted ROV as its vehicle. The 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. Development of ABISMO. 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. 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.