1998 Year of the Ocean The Legendary Ocean — ^The Unexplored Frontier 



finding of chemosynthetic life at hydrothermal vents, studies of undersea volcanoes and their 

 eruptions, and hundreds of previously unknown species of deep-sea animals. Worldwide, an 

 estimated 1,000 submersible dives per year have taken place since 1970. 



Remotely operated vehicles (ROVs), which are tethered, unoccupied robots, have been 

 highly developed and provide some significant advantages over occupied submersibles. They 

 have almost unlimited bottom time, their damage or loss endangers no human lives, and their 

 telepresence capability allows a broader audience to be "present." Vehicles range from the small 

 and portable, capable of working at only a few tens of meters, to the large and somewhat 

 cumbersome (1 1,000 pounds), capable of working at 10,000 meters while carrying many 

 different sensors and tools. Since the early 1970s, more than a 1,000 ROVs have been placed into 

 service worldwide in support of various tasks including oil exploration and operations, offshore 

 development, and undersea research. In 1966, an ROV was used to find a hydrogen bomb lost at 

 sea after an accident off the coast of Palomares. Spain. Using the ROV Kaiko, Japanese scientists 

 revisited the Mariana Trench in 1 995 and documented observations of shrimp, a scale worm, and 

 a sea cucumber at 10,91 1 m (35,800 ft). 



Autonomous underwater vehicles (AUVs) have been recently developed to augment 

 occupied submersibles and ROVs as exploration vehicles. Most of the AUVs now in service are 

 experimental test platforms, although several have been used for scientific purposes. Because 

 AUVs are untethered they can have a much greater horizontal excursion capability than an ROV. 

 Long-range AUVs are currently limited by the lack of cost-effective power supplies. 

 Nevertheless, the future for computer-guided, unoccupied, untethered vehicles appears 

 promising. 



Technological advances notwithstanding, humans are still an important part of 

 exploration. Divers are better at working around delicate undersea communities and 

 archeological excavation sites than are robots, and trained observers remain the best detectors of 

 many phenomena, i.e., they do not need to be programmed to identify unexpected discoveries. 



Acoustic technology, including sonar (sound navigation and ranging), has become an 

 essential tool for marine exploration. Sound penetrates the ocean much as light penetrates the 

 atmosphere. Sound is carried through water much more readily than it is through air; depending 

 upon frequency, volume, and water characteristics, sounds can be heard thousands of kilometers 

 from their origin. Acoustic technologies are used to explore the distribution of animals in the 

 water, the nature of the sea bottom, to locate objects, discover natural resources, provide 

 undersea navigation, detect submarines, and to improve our understanding of the nature of the 

 ocean itself . With the development of side scan sonars and deep towed echo sounders in the 

 1960s, detailed sea bottom mapping, which is essential to understanding plate tectonics and other 

 geological processes, has become possible. The recent marriage of computers with acoustic 

 technologies has resulted in the introduction of mapping systems that can provide wide area 

 images of the seabed in real time. 



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