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Underwater Exploration

Underwater Exploration

History

Oceanography

Instrumentation

Diving tools and techniques

Deep-sea submersible vessels

Deep-sea pioneers

Key findings in underwater exploration

Deep seas, the final frontier

Resources

Underwater exploration is the relatively recent process of investigating the depths of the sea to understand its physical and chemical characteristics and to learn about the life forms that inhabit this realm. Underwater exploration near the surface and near the shore is an ancient form of earning a livelihood and enjoying the pleasures of the water; but deep-sea exploration is a recent phenomenon (compared to many other sciences) because technological developments have been essential to the survival of human beings in deeper water. Alternatively, these developments have eliminated the need for humans to journey to these depths.

History

the very earliest explorations of the sea depended on human endurance, that is, the depth a person could sustain a dive. Ancient human ancestors certainly explored the near shore. The Polynesians dived from their sea-going outrigger canoes, but the depth they could explore was limited to relatively shallow water. The women who dive for pearls in and near Japan and the Greeks who dive for sponges have achieved phenomenal endurance records (presumably in ancient as well as modern times) for holding their breath, but diving for pearl-bearing oysters or for sponges requires perseverance for searching not for depth.

Scientific study of the physics of the deep sea began when French mathematician, astronomer, and scientist Pierre Simon de Laplace (17491827) used only tidal motions along the shores of West Africa and Brazil to calculate the average depth of the Atlantic Ocean. He estimated this average to be 13,000 ft (3,962 m), which scientists later proved with soundings over the ocean to be relatively accurate. Investigations of the sea bottom were begun when submarines were manufactured, and soundings were used to lay submarine cables.

Nineteenth and twentieth century technology caused an explosion in the exact sciences. The captains of sailing vessels made precise ships logs in the early nineteenth century that proved valuable in early oceanography. These records were compiled by Matthew Fontaine Maury (18061873), who set documentation standards later followed by many international congresses on oceanography and other sciences of the sea. The expeditions of Captain James Cook (17281779) and the polar explorers (notably Sir James Ross [18001862] who explored the North Pole with Sir William Edward Parry [17901855] as well as the Antarctic Region and his uncle Sir John Ross [1777 1856] who was also an explorer of the North Pole) added more information about oceanic surfaces.

In the mid-1800s, Norwegian scientists proved life exists in the deep sea when they recovered a stalked crinoid from a depth of 10,200 ft (3,109 m). In 1870, the British began the first expedition strictly to explore the deep ocean. The H.M.S. Challenger expedition left England in December 1872 and spent four years conducting oceanographic studies in the oceans of the world, returning to England in May 1876. The ships crew was under the command of Sir George Nares, and Sir Charles Wyville Thomson (18301882) was the chief scientist on board. The crew is credited with discovering 715 new genera and 4,417 new species of marine organisms. At about the same time, the German ship the S.M.S. Gazelle made observations of southern waters including the South Atlantic, South Pacific, and Indian Oceans. The U.S.S. Tuscarora cruised the North Pacific to make soundings for the trans-Pacific cable line and recorded many other scientific observations along with the soundings.

Oceanography

oceanography is literally the science of mapping the floor, geometry, and configuration of large bodies of water. The history of deep-sea exploration began with practical applications of oceanography, such as the laying of undersea cables, and was extended by natural and scientific curiosity. Aspects of the condition of the oceans studied by oceanographers include relief of the sea floor; volumes of ocean basins and numerous sub-areas; character of the ocean surface including atmospheric effects, transportation and properties of sediments found in marine environments (as well as their origins, such as land, volcanic, organic, and inorganic sources); chemistry of sea water (including the gas content); physical properties of sea water like density and pressure; characteristics of ice and icebergs; and biological oceanography (including plankton, bacteria, and plant nutrients as well as more familiar plants and animals).

Based on the surface map of the world, the oceans cover 71% of the globe. In the twentieth century, oceanography has dramatically changed scientific understanding of the importance of the sea to land dwellers. Not only have people become more environmentally aware, but humans are more knowledgeable of the vastness of Earths seas.

Oceanography led to the development of a number of instruments that are used to chart the bottom of the sea; some of these are also used in undersea exploration for other purposes. Sounding devices were the first key oceanographic tools. The first sounding weight, the Baillie sounding machine, was used on the Challenger expedition and consisted of a large weight dropped to the sea floor. When the weight hit the bottom, the line was pulled taut and the depth measurement was read from the line. The Baillie sounding machine also had a tube below the weight that drove into the sea-floor sediments. Samples could be retrieved in this fashion. Early explorations also collected samples from the seabed using dredges (that were pulled along the sea floor) and an assortment of scoops. These tools collected soil, rock, some plant life, and other biological specimens.

Weight-sounding techniques were replaced after World War II (19391945) by echo-sounding that uses sounds or acoustic impulses from ships on the ocean surface to measure reflections of the sound waves off the bottom. The time lapse of the sound waves return to the ship indicates the depth, although early uses of echo-sounding were often in error if the device was not properly calibrated for the density of saltwater.

Instrumentation

oceanographers also use drilling and coring techniques for sampling the seabed. The gravity corer replaced the sampling device on the Baillie sounding machine with an open and weighted tube that is triggered to release as soon as sediments are encountered. It then drills into the sea floor to up to about 33 ft (10 m). When the corer is extracted and brought onboard ship, the core can be extruded. Layers in the sediments are then logged by a geologist specializing in ocean sediments. Some specially equipped ocean drilling rigs are able to retrieve core samples from greater depths (as much as 4,900 ft or 1,500 m), and samples from the drilling of test wells for oil and gas extraction and the foundations for offshore oil platforms are also examined by oceanographers and other specialists.

Other oceanographic instruments include flow meters for measuring the velocity of deep-sea currents, seismographs for detecting earthquake activity far from land-based equipment, pressure meters that measure pressure beneath the ocean with depth, and thermometers. These instruments are usually attached to sounding devices because their measurements with respect to the depth to the sea floor are important. Research vessels carry these instruments, but the instruments can also be tethered to buoys and left at sea. The research ships themselves are precise, highly equipped floating laboratories with sophisticated navigation systems including links to global positioning system (GPS) satellites and positioning systems that use computers in the ships controls to keep it in a fixed location at sea. A sonar beacon seated on the ocean floor usually provided the point of orientation for the ships fixed position. A variety of television, video, and still cameras and audio detection equipment is also standard for research vessels.

Satellite technology has greatly advanced the science of oceanography. One of the techniques, known as satellite altimetry, utilizes radar to measure the distance from an orbiting satellite to the ocean surface. While usually considered smooth and spherical, the surface of the Earths oceans actually exhibits a multitude of broad dimples and bulges that reflect the topography of the ocean floor. The uneven surface of the ocean is due to localized gravity effects from mountains and depression at the bottom of the ocean. Although the relief of these prominences is greatly subdued when compared to the ocean floor, their extent is sufficient to be quantified by means of satellite altimetry, which has an astounding vertical resolution of 1 in (0.03 m). The altimetry data provided by the U.S. Navys GEOSAT (Geodetic Satellite) and European Space Agencys (ESAs) ERS-1 (European Remote-Sensing-1) satellites permit the construction of topographic maps of the worlds ocean basins. This is particularly important in deep, remote portions of the basins where little depth information is available.

Modern surface mapping techniques of similar resolution would require approximately 125 years and several hundred million dollars to complete.

The technique has a wide variety of applications. Navigation of ships, submarines, and even aircraft are frequently affected by local gravitational variations. The information provided by satellite altimetry allows the variations to be accounted for and the course corrections applied. The topographic information permits the identification of subsurface controls of ocean currents and favorable fishing locations. Geologists utilize the information to investigate various aspects of plate tectonic theory, identify and study subsurface volcanoes, locate potential petroleum reserves, and even measure the structural characteristics of the Earths oceanic crust.

Diving tools and techniques

Diving suits and devices to help divers stay longer underwater were invented and tested as early as the fourth century BC. At that time, Aristotle (384322 BC) mentioned in his writings about artificial breathing devices for divers, and Alexander the Great (356 323 BC) supposedly dove in a primitive version of a diving bell. Edmund Halley (16561742), the British astronomer, geophysicist, and mathematician for whom the comet is named, invented the first practical diving bell in 1717. It had a wooden chamber with an open bottom and glass in the top or ceiling for light. Leather tubes supplied air to the occupants, and the air was furnished through casks lowered into the water as they were needed. As water flowed into the casks, it forced the air out through the tubes, in a simple form of compressed air. Steel chambers similar to Halleys invention are still used today for some types of underwater construction, except that the compressed air is supplied from tanks.

Individual diving suits to protect divers and let them move freely were first tried in the seventeenth century. In 1819, the first successful diving suit was invented by Augustus Siebe (17881872), an inventor of German and British extraction. He used the principle of the diving bell in fitting the divers head into a metal helmet that was attached to a leather jacket. Air was pumped into the helmet through a hose. The system was not watertight, but the forced-air pressure kept the water below the divers nose and mouth. Siebe followed his invention with several improvements, the last of which was made in 1830. The modern diving suit fully encloses the diver in a suit of rubberized fabric and a helmet. The unit is airtight, and the diver can regulate both air pressure and buoyancy with valves on the helmet. Diving suits for greater depths include weighted shoes, lead plates for the back and chest, and a communications line linked to a telephone at the surface. For still greater depths, metal suits with special airtight joints help divers withstand the higher water pressures. Air pressure within these suits can be properly regulated so, in fact, the suits for greater depths impose less physical stress on the diver than those for shallower waters. Self-contained underwater breathing apparatus (SCUBA) supports both skin divers and divers with gear for deeper water and eliminates the troublesome supply hoses.

Work underwater is done with special equipment that is also pneumatically powered (powered by compressed air). Drills, wrenches, and other tools require supplied air for power although standard cutting and welding torches can be used underwater. Electrically powered lights are needed at depth because light only penetrates a few yards (meters) in some waters. Underwater stations for working and habitation have been tested; depending on depth, different air supplies using mixtures of oxygen and helium or hydrogen instead of nitrogen are needed to prevent fatal bubbles in the blood stream of the diver. Divers adapt to the underwater world in stations no more than 328 ft (100 m) deep, but they can work for shorter periods of time at depths of 1,300 to 1,500 ft (approximately 400 to 650 m) in flexible suits. Underwater habitats or stations are supplied air and power by stationary surface craft.

Deep-sea submersible vessels

The tool that made true exploration of the deepest waters of the seas possible is the deep-sea submersible vessel or vehicle, simply called a submersible. The submersible is a miniature submarine, but submarines are not submersibles. Submarines are fully contained quarters for human occupancy and for machines, usually with a military purpose, that can survive at depth for an extended length of time. Some nuclear-powered submarines stay submerged for months, carry food and fresh water for crews of over 100 persons, purify air for breathing, and perform specific tasks related to warfare, espionage, and research. While they also have highly sophisticated equipment, including sounding devices, pressure and temperature meters, and elaborate navigation and power systems, these are used for different purposes than the instruments on a research ship or submersible.

Submersibles are designed to dive to much greater depths than submarines. Because of the tremendous pressures in the deep ocean realms, they are built for strength, survival of two or three human occupants (if any), and specific research tasks. They do not carry stores of food or water, and oxygen is furnished from limited onboard storage tanks or piped in from the support vessel at the surface.

Early submersibles were called bathyscaphs from the Greek roots for deep and boat, bathyspheres meaning deep-diving spheres, or diving saucers. The bathysphere was a steel diving chamber suspended from a host ship at the surface on a steel cable and a separate telephone cable. The bathyscaph also had a steel diving sphere, but it was suspended beneath a football-shaped blimp that carried gasoline to keep the craft afloat until the crew wanted to make the bathyscaph descend. For descent, the gasoline was released, and it was replaced with seawater. Diving saucers were a specialty of the French; explorer and researcher Jacques-Yves Cousteau (19191997) designed an early diving saucer called the Soucoupe (the French word for saucer) that was unique in using hydrojets to maneuver in the water. Later, saucerlike vessels, the Deepstar 4000 and the Cyana, also made landmark explorations into the underwater world. The Cyana was used in 1974 in the pioneering exploration of the Mid-Atlantic Ridge and its deep rift valley.

A number of countries around the world operate submersibles through their oceanic research organizations. Manned submersibles have descended to over 20,000 ft (6,000 m) deep; one of these, the Argo, was used by Dr. Robert Duane Ballard (1942) to locate the wreck of the H.M.S. Titanic in 1985. After the Titanics location was discovered using a manned submersible, a smaller, unmanned robot submersible named Jason ventured into the wreck to photograph its interior. Most submersibles carry still cameras, television systems, and special lighting systems to provide light for photography. All of these are designed and built specifically for the deep-ocean environment and its severely limiting hardships. Many submersibles are also equipped with mechanical manipulators (arms and scoops) that can collect samples from the sea floor, biological specimens, and oddities such as debris from the Titanic. Later, Ballard discovered the battleship Bismarch, in 1989, the aircraft carrier U.S.S. Yorktown, in 1998, and the PT-109 (where PT stands for Patrol Torpedo) boat that was wrecked with Lieutenant (and future president) John F. Kennedy (19171963) onboard, in 2002.

Deep-sea pioneers

Charles William Beebe and Otis Barton

Charles William Beebe (18771952) was the designer of the first practical bathysphere. Beebe, part scientist and part showman, never completed his degree at Columbia University in New York: instead, he became a curator at a zoo, tracked rare species of birds in South and Central America, and climbed volcanoes before becoming interested in underwater exploration. In 1934, he and Otis Barton made a record-setting descent to 3,028 ft (923 m) below the waters off the Bermuda Islands. Barton was a far different character, a virtual recluse who had been born to an extraordinarily wealthy family and was interested in the ocean from his youth. Barton invented his own deep diving helmet and weighted himself down with rocks to explore Massachusetts waters before teaming up with Beebe.

By 1926, Beebe was famous as an adventurer; Barton contacted him and showed him detailed designs for a steel sphere that would serve as a capsule for carrying two passengers beneath the sea. Two oxygen tanks in the sphere carried eight hours worth of air, trays of absorbents collected carbon dioxide and moisture, and panes of quartz that had been pressure-tested were fitted into the sphere as windows. Conditions were so primitive that Beebe and Barton carried small palm-leaf fans to circulate air in the chamber. A steam-powered winch on the host ship hoisted the bathysphere to the surface on a steel cable, and another cable carried two wires for telephone communications with the surface and two for an electric searchlight mounted inside the sphere and aimed through a window. Beebe wore headphones during the dives and described observations by telephone to an assistant onboard the surface craft.

During their historic 1934 dive, the captain of their crew allowed the bathysphere to stay at its greatest depth for only three minutes before beginning the surface ascent. Beebe described eerie and extravagant undersea creatures as well as great water voids with no apparent life. For years, he was condemned for deceiving the public until the observations and photographs made by others verified his observations, and Beebe was officially credited with discovery of hundreds of new life forms.

Auguste and Jacques Piccard

Swiss physicist Auguste Piccard (18841962) had twin fascinations, the atmosphere above the Earths surface and the sea below. He was world-famous as an inventor (who collaborated with GermanAmerican physicist Albert Einstein [18791955], among others), balloonist, and adventurer, and, at the Chicago Worlds Fair in 1933, his hydrogen-filled balloon was displayed next to Beebes bathysphere. This led to a meeting of the two like minds, and, in 1937, Piccard began building his bathyscaph with its gasoline-filled float and suspended chamber or gondola of spherical steel. Largely supported in his atmospheric explorations by the Belgian organization Fonds National de la Recherche Scientifique (FNRS), Piccard asked them to back him in building the bathyscaph, named FNRS-2 (his atmospheric exploration balloon had been named FNRS-1). His research was suspended for the duration of World War II, but, in 1948, Piccard and his son Jacques (1922) reached a new record depth of 4,500 ft (1,500 m). Jacques was educated in Trieste, Italy, and, in 1953, the Piccards in a new Swiss/Italian bathyscaphe named Trieste engaged the French/Belgian FNRS in a battle to beat the Piccards last depth record.

In September 1953, the Piccards set the new record of 10,390 ft (over 3,100 m), they were limited only by the depth of the Mediterranean Sea. The U.S. Navy joined the race in 1957 and wanted to purchase the Trieste for test dives and further attempts at world records in the Pacific Ocean off the coast near San Diego, California. The ultimate objective was a dive into Challenger Deep, the deepest hole in the worlds oceans in the Mariana Trench near Guam where the Pacific forms Mount Everest in reverse, a 35,800-ft deep (over 11,400-m-deep) chasm discovered in 1949 by the H.M.S. Challenger II research ship. The Big Dive was scheduled for January 23, 1960, and Jacques Piccard was selected by the Navy as half of the twoman crew with Lieutenant Don Walsh. After descending at the speed of an elevator and having their fragile craft buffeted by thermoclines (differences in ocean temperatures), Piccard and Walsh reached the deepest known point on the Earth. With the depth race over, the oceans were open to more thorough scientific exploration. AS of 2006, Piccard and Walsh are the only two people to have reached the deepest point (the Challenger Deep) on the surface of the Earth.

Maurice Ewing

Maurice Ewing (19061974) was a professor of geology at Lehigh University in Lehigh, Pennsylvania. He had used seismic reflection, a technique for bouncing mini earthquake waves generated by explosives off surfaces and measuring their reflections, to locate deep oil and gas reserves in Texas. Different types of rock and other materials reflect seismic waves of different wavelengths. He was approached about applying the same method over the ocean to map the continental shelf, the border of any continent at the point where it drops steeply to deep ocean. In 1934, Ewing began a study of the continental shelf off the coast of Virginia. In 1940, Ewing went to the Woods Hole Oceanographic Institute (Massachusetts) to learn about the sea, and, during World War II, he performed secret research for the U.S. Navy and worked with Allyn Vine and John Worzel to develop the first underwater cameras. He was a leader in developing techniques for sampling soil from the sea floor and in investigating the Mid-Atlantic Ridge; he also discovered the great rift that divides this ridge. For 40 years, these and Ewings other pioneering techniques were used to establish depths, bottom characteristics, and conditions below the sea floor, not just along the continental shelf but over the deepest oceans.

Sylvia A. Earle

American oceanographer Sylvia Alice Earle (1935) extended public awareness of the need to preserve the environment from beyond the shore to the deepest ocean. She spent 40 years working as a marine scientist, assisting government agencies, writing, lecturing, and establishing records for diving and exploring her ocean world. In 1968, she joined a submarine crew on a Smithsonian program for exploring the ocean and fell in love with its challenges and habitats. In 1970, she led a team of women scientists in the Tektite II Project in which the team lived underwater for two weeks to help develop techniques for survival in confined circumstances, which were also intended to be used in the space program. The media dubbed these women the aquababes, and Earle learned the power to educate through media coverage. She set her first deep diving record in 1979. The experience so intrigued her that she and British engineer Graham Hawkes built a deep-water submersible called the Deep Rover and, later, the Phantom, a remotely operated vehicle (ROV). In 1990, she was named the chief scientist of the National Oceanic and Atmospheric Administration (NOAA), the first woman to hold that post. Earle continues to campaign for improvements in the sea and popular support for the ocean environment.

Allyn Vine

The deep-sea submersibles that provide so many stunning images from the depth of the ocean are Allyn Vines (19411994) work. Vine had worked with Maurice Ewing at Lehigh University and on the Atlantis, the Woods Hole Oceanographic Institutions research vessel. In the 1940s, there were about 45 ocean research vessels around the world, but all of them had the same capabilities with limited ability to explore the greatest depths of the ocean. Vine obtained funds from the U.S. Navys research department to design and build a deep sea submersible, a miniature submarine that could withstand the tremendous water pressures at depth, hold a crew of only two or three, powered by golf-cart batteries, controlled by a mother ship at the surface, and host a number of cameras, sampling devices, and instruments. The passenger ship on the submersible was fully detachable; if the main craft could not rise to the surface, the passenger ship would. In 1964, the first submersible called Alvin, for the first two letters from Allyn and the first three from Vine, was ready for a deep-dive test. The Alvin was successfully certified on her first deep dive. In 1994, after thousands of improvements, she celebrated her thirtieth birthday and 2,772 dives in the name of scientific research. As of October 2006, Alvin continues to be used for research missions. On August 6, 2004, however, the National Science Foundation announced the construction of a next-generation submersible. When completed, the new submersible would be able to dive over 21,000 ft (6,500 m), along with being equipped with the most advanced instruments available.

Vines early experience, in the company of Ewing, was with the Navy during World War II in testing and improving the bathythermograph (BT), a device that measures temperature differences with depth in sea water. Because temperature and density in water are directly related, enemy submarines could hide from detection by sonar from the surface by hiding in dense water. Vines improvement of the BT helped the Navy capture and destroy enemy subs but also helped its own subs find the most efficient hiding places.

Robert D. Ballard

Robert Ballard (1942) is best known as the discoverer of the wreckage of the H.M.S. Titanic, the legendary ocean liner that in theory could not be sunk, but crashed to the ocean floor on her maiden voyage in 1912, taking over 1,500 lives with her. However, Ballard is a geologist and oceanographer with many other astounding achievements to his credit. He was the first to take a submersible on a dive of the Mid-Atlantic Ridge, and, in an exploration of the volcanic sea floor around the Galápagos Islands, he discovered new life forms around hydrothermal vents at depths thought impossible for life. He investigated the sunken nuclear submarines the Thresher and the Scorpion, but finding the Titanic was a dream. An avid researcher, author, and writer of technical papers, Ballard used the fame that came with the discovery of Titanic to launch the JASON Project to educate schoolchildren about undersea explorations; through satellite links, the students can view the findings of submersibles as they work and even help manipulate it. The JASON Project was named for the Jason robot or ROV (remotely operated vehicle) that Ballard used to photograph the interior of the Titanic; Ballard describes the Jason ROV as a tethered eyeball.

Jacques-Yves Cousteau and Calypso

For his immeasurable contribution to oceanography and the preservation of the wealth of the seas, Jacques-Yves Cousteau (19101997), a former French sailor, deserves special mention. After his education at the French Naval School at Brest, Cousteau served as a gunnery officer and became fascinated with the depths of the sea. During and immediately following his Navy career, Cousteau dived underwater extensively himself, experimented with diving equipment, and created the improvements he needed. His underwater inventions were many, but the most notable is the aqualung or SCUBA (Self-Contained Underwater Breathing Apparatus), which he and Émile Gagnan (a French engineer) designed in 1943. The aqualung consists of a facemask, a pressure-regulating valve, and an attached cylinder of compressed air that enables a trained diver to stay underwater for several hours. For the first time, an individual could go beyond his own breathing limitations in exploring the sea. In the 1940s, he was named captain of the Ingènieur Elie Monnier, the worlds first marine research vessel and the pride of the French Navy.

In 1950, Cousteau obtained indefinite leave from the Navy to devote himself to underwater exploration (he was to retire from the Navy with the rank of corvette captain in 1957). He needed a research vessel himself and found one in Calypso, a former minesweeper that had been built for the British Navy in World War II and served as a ferryboat around the island of Malta after the war. The ship was extensively remodeled to work as a floating laboratory. British brewery heir Noel Guinness provided funding for this project. Accommodations were overhauled, sophisticated navigation and exploratory instrumentation was installed, and a false nose, or underwater observation chamber, was constructed on the tip of the ships prow in a metal cage. Rigging and facilities for diving equipment were also installed.

Aside from pure oceanography, Calypso was equipped to study and monitor patterns of biological populations, behavior of coastal and marine animals, the shapes and operations of a coral reef, the effects of undersea instruments, and special diving conditions and equipment performance. Her other assignments included topography, weather, acoustics, geology, chemistry, physics, and geophysics. Other private sources, the French Navy, manufacturers, and even donations from school children kept Calypso constantly moving about the worlds oceans, making discoveries that benefited and educated the world. In 1951, Cousteau put Calypso to sea with his wife and two sons (among others) as crew. Operating from a base in Toulon on the French Mediterranean, and under the administration of the Campagnes Oceanographiques Franaises (COF) or French Oceanographic Expeditions (a nonprofit organization), Calypso began her voyages of discovery.

Cousteau brought Calypsos voyages into many families living rooms thanks to his other skills as an underwater photographer, maker of documentary films, and author. Cousteau learned underwater photography and deep-sea photography at the feet of a master; in 1953, he began working with Doctor Harold Edgerton, known as Papa Flash, who had pioneered deep-sea cameras and the use of strobe lights for flash as an inventor and electrical engineer at the Massachusetts Institute of Technology. Cousteau and Edgerton developed a sonar device to trigger a flash near the sea floor and a sled-like device for mounting cameras. By separating the cameras from the flash sources, the pair took some of the most remarkable deep-sea photographs ever seen. Cousteaus first film debuted in 1943. He made full-length films, documentary shorts, and many made-for-television films. Two of these, The Silent World (1956) and World Without Sun (1966) won Cousteau Academy Awards for best documentary feature. His best-known books may be those in the series called The Undersea World of Jacques Cousteau. The books, films, and television programs interested many children in the mysteries of the underwater world and help expand the environmental movement beyond the confines of land.

In the 1960s, Cousteau started a series of experiments in building underwater habitats where people could work and live. These concepts were abandoned because of economics, but, again, they awakened the publics interest in the compatibility of humans and the underwater world. He turned more strongly toward environmental interests in the 1970s and started the Cousteau Society for marine conservation before his death in 1997.

Key findings in underwater exploration

The invention and improvement of the submersible from about 1930 to the early 1970s opened the possibility of vastly improving scientific understanding of the extremes of the deep. This watery world is so enormous and full of mysteries that nearly every submersible dive introduces new life forms or discoveries leading to greater knowledge of the mechanics of the planet. Some of the landmark studies involving submersibles are the 1974 exploration of the Mid-Atlantic Ridge, the 19791980 study of the rift valley near the Galàpagos Islands off the coast of Ecuador, and the 1985 discovery of the wreck of the Titanic.

In 1974, a French-American team of scientists explored the great rift in the Mid-Atlantic Ridge by using occupied submersibles and a collection of support ships. The FAMOUS Project (French-American MidOcean Undersea Study) used the American submersible Alvin, the French diving saucer Cyana, and the French bathyscaphe Archimõde to dive into the rift south of the Azores Islands, where geologists believe two great plates of the Earths crust, the Eurasian Plate and the North American Plate, are pulling away from each other allowing magma (molten rock) to flow into the rift and the sea floor to enlarge or spread. The research ship the Glomar Challenger was the sea-level base for the submersibles and was assisted by a small flotilla of support ships. Manipulators collected samples of solidified, but geologically young, magma on the submersibles, and over 5,200 photographs were taken in this region. Exploration would have been impossible without the submersibles; in some places, the edges of the Cyana, which was about 7 ft (2.1 m) in diameter, nearly touched both sides of the ridge and hovered over the depths of the rift that are far greater than the highest mountains on the Earths surface. Analysis of the findings from the FAMOUS Project proved that the central fissure of the rift valley is widening by about 1 in (2.5 cm) per year. It is also adding substantially to both proving and helping scientists understand plate tectonics (the motions of the massive plates comprising the Earths crust) and sea-floor spreading (the separations of those plates beneath the sea where new crustal material is made).

The 19791980 study of the Galàpagos Rift was begun as a further study of sea-floor spreading but found it occurring in a very different environment. Mexican, French, and U.S. scientists united efforts and discovered expanses of hydrothermal vents, which are chimney like growths on the seabed that discharge hot springs of mineral-rich water. The water temperature of these vents is about 570° F (300° C), and the vent chimneys are about 12 ft (3.7 m) in diameter and 30 ft (9 m) tall. The smoky plumes of dissolved metals form deposits laden with nickel, copper, uranium, cadmium, and chromium; and the ecological community supported by the hot springs is rich in plants and animals that would have remained hidden without the camera eyes of submersibles. The hydrothermal vents and their surrounding communities proved that the deep sea is neither the barren abyss nor the realm of sea monsters of popular imagination.

Deep seas, the final frontier

Future exploration of the oceans of the world parallels the exploration of outer space in many ways. To increase understanding of both, technologies are being merged in creative ways. In the Arctic Ocean Basin, a submarine and sophisticated acoustics are combined to measure water temperature. The U.S.S. Hawkbill, a

KEY TERMS

Bathyscaph A deep-sea exploration vehicle or submersible consisting of a ballast-filled float (resembling a blimp or balloon) with a spherical metal gondola for carrying occupants and equipment suspended below it.

Bathysphere A deep-sea exploration vehicle or submersible consisting of a sphere that carries a crew and equipment and is lowered to the sea floor on a cable.

Bathythermograph (BT) An instrument for measuring the differences in temperature in sea water depths.

Black smokers Hydrothermal vents on the sea floor that emit black clouds of hot, mineral-rich water much like a chimney belches black smoke.

Continental shelf A relatively shallow, gently sloping, submarine area at the edges of continents and large islands, extending from the shoreline to the continental slope.

Diving bell An enclosed device for carrying a single diver exploring relatively shallow waters; replaced by submersibles except in some work situations.

Global Positioning System (GPS) A system of satellites whose signals can be used to locate objects on the Earth (including below sea level) very precisely.

Hydrothermal vent An opening of the Earths crust on the sea floor where hot springs bearing mineral-rich waters are emitted. Hydrothermal vents are important sources of minerals and warmth for species of life not found in other environments.

Magma The molten rock from the core of the Earth that emerges on the surface through volcanic eruption and sea-floor spreading. When magma cools, it forms igneous rock.

Oceanography The science of measuring the ocean.

Plate tectonics The theory now widely accepted that the crust of the Earth is composed of about 12 giant plates that form the land masses and sea floors and that grind slowly past each other, causing earthquakes, mountain-building, and other large-scale geologic occurrences.

Remotely operated vehicle (ROV) A deep-sea submersible that carries equipment only (no human occupants) and can be remotely operated from a surface ship.

Rift valley A large, deep valley, either on the land surface or beneath the sea, created by the movement of two plates composing the Earths crust away from each other. The Mid-Atlantic Ridge, the Marianas Trench, and the Galápagos Rift are examples of submarine rift valleys.

Sea-floor spreading The part of plate tectonics that describes the movement of the edges of two of the plates forming the Earths crust away from each other under the ocean. Sea-floor spreading results in the formation of new submarine surfaces.

Sediment Soil and rock particles that wash off land surfaces and flow with water and gravity toward the sea. On the sea floor, sediment can build up into thick layers. When it compresses under its weight, sedimentary rock is formed.

Self-contained underwater breathing apparatus (SCUBA) Also called an aqualung. The mask, mouthpiece, valves, and oxygen or compressed air tank that can be worn by a diver to sustain breathing for periods up to several hours under water.

Sounding The process of using dropped weights (weight sounding), sound waves (sonar), or seismic waves artificially induced by man-made explosions to produce waves that, when reflected back to their source, can be used to measure distances and the densities of the materials through which the waves pass.

Submersible Deep-sea exploration vehicles that carry two or three human occupants, cameras, and other equipment to relatively great depths in the ocean. Submersibles can also carry equipment only and be remotely operated.

Thermocline A difference in temperature in sea water or in the atmosphere.

nuclear attack submarine operated by the U.S. Navy, launches acoustical probes that measure the density, salt content, and temperature of seawater along the path of the sound. The Hawkbill is part of a research platform for SCICEX 99, the fifth year of a working relationship between the Navy, the National Science Foundation, and other federal departments interested in the relationship among the atmosphere, oceans, and climate. The acoustic tests performed by the Hawkbill show a pattern of shrinkage and growth, which enters into scientific understanding of the importance of the ice cap. As of 2006, however, the ice cap is continuing to shrink as a result of what some scientists contend is changing climate, or global warming.

Exciting underwater finds like the discovery of the Titanic have led to a burst of shipwreck hunts. The Titanic adventure proved that the technology exists to find any lost vessel anywhere, and all parties from historians to gold grabbers are looking for Spanish galleons, passenger liners, Roman vessels, and historic ships for their cargo and the answer to questions about their fate. Ethical and legal questions have arisen over control of shipwrecks; apart from monetary value, their contents are historically and scientifically important. The United Nations Economic, Scientific, and Cultural Organization (UNESCO) has drafted a treaty establishing the limits of a nations cultural underwater heritage offshore, which may help regulate the hot underwater marketplace. Even television rights for photographing discovered wrecks is highly contested.

Similarly, the underwater riches that occur naturally as mineral deposits are being mined at shallow depths, but the rights for deep sea minerals are contested. The black smokers, or hydrothermal vents, in the Mid-Atlantic and other rift zones belch minerals like smoke, but these minerals include gold, lead, and silver. Undersea craters off the coast of Japan were discovered in 1998 and are thought to have over $2 billion in mineral riches on and near them. Deep-sea submersibles are an expensive ($1 million per month at sea) but available tool for harvesting the minerals, but these vents also support exotic life forms, including tube worms, anemones, and giant clams that are not found in any other Earth environment. Just as archaeologists are contesting shipwreck hunters over historical disasters, marine biologists are trying to compete with the mining industry in preserving natures secret treasure trove.

Pure observation to further scientific knowledge of the underwater world is also progressing, thanks to technology. Off shore near New Jersey, the Long-Term Ecosystem Observatory (LEO; Rutgers University) has been constructed to record a battery of measurements of physical, chemical, and biological state of the sea. Complex instrument packages along with instrument-bearing torpedoes and surface vessels transmit, collect, and convert a variety of signals into information about the ocean. An underwater habitat named Aquarius, operated by NOAA, is sited off the Florida coast about 60 ft (20 m) under water. Aquanauts including Sylvia Earle are studying coral reefs that indicate the health of near-shore waters but also the deep ocean. The Monterey Bay Aquarium uses two remotely operated vehicles (ROVs) for similar purposes of probing the characteristics and life forms in the deep canyon under the Monterey (California) Bay.

Despite the huge technological leap into deep waters in the twentieth century, and now into the twenty-first century, there are other creative ways of exploring underwater. A team from the Smithsonian Institution is using natural enemies to its advantage. To attempt to film giant squid in their natural environment, the Smithsonian is using a crittercam, a video camera attached to an animal to pursue and film this elusive creature. The sperm whale preys on the giant squid, and, using a suction cup to mount a small video camera on the whales back, scientists hope to obtain candid shots of the squid. The whales are not expected to return the camera for processing; instead, the camera films for three hours and, then, releases the suction on the cup. It proceeds to float to the surface.

Similarly, scientists at McMurdo Station, Antarctica have attached cameras to Weddell seals to study the ecology of fishes living beneath the sea ice. In this case, wild seals are captured and fitted with photographic and other sensing equipment. The seals are taken to an isolated area of sea ice with no natural breathing holes. A hole is drilled into the ice and the seals are allowed to hunt freely. Because there are no other options, the seals must return to the artificial hole for breathing. The equipment allows the scientists to monitor the activities of the seals and environment in which they and their prey exist. Once the information is collected, the equipment is removed from the seal and it is released at the location it was captured.

See also Abyssal plain; Seamounts.

Resources

BOOKS

Ballard, Robert D. Adventures in Ocean Exploration: From the Discovery of the Titanic to the Search for Noahs Flood. Washington, DC: National Geographic, 2001.

Corfield, R.M. The Silent Landscape: In the Wake of HMS Challenger 18721876. London, UK: John Murray, 2004.

Gould, Carol Grant. The Remarkable Life of William Beebe:Explorer and Naturalist. Washington, DC: Island Press/Shearwater Books, 2004.

Hitchcock, Susan Tyler. Sylvia Earle: Deep-sea Explorer.Philadelphia, PA: Chelsea House, 2004.

Jochum, Markus, and Raghu Murtugudde. Physical Oceanography: Developments since 1950. Chicago, IL: University of Chicago Press, 2006.

Medwin, Herman. Sounds in the Sea: From the Ocean Acoustics to Acoustical Oceanography.Cambridge, UK, and New York: Cambridge University Press, 2005.

Stow, Dorrick A.V. Oceans: An Illustrated Reference.Chicago, IL: University of Chicago Press, 2006.

Nichols, C. Reid. Recent Advances and Issues in Oceanography. Westport, CT: Greenwood Press, 2003.

Petrie, Kristin. Jacques Cousteau. Edina, MN: Abdo Publishing, 2004.

Trujillo, Alan P. Essentials of Oceanography. Upper Saddle River, NJ: Pearson Prentice Hall, 2005.

Wertenbaker, William. The Floor of the Sea: Maurice Ewing and the Search to Understand the Earth. Boston, MA: Little, Brown, 1974.

OTHER

Billings, Alistair W. Through Wiser Eyes: Scientists Let Weddell Seals Do the Walkin. Cyber Diver News Network. January 19, 2002. <http://www.cdnn.info/eco/e020119/e020119.html> (accessed November 4, 2006).

Coastal Ocean Observation Lab, Institute of Marine and Coastal Sciences, Rutgers University. Coastal Predictive Skill Experiments at LEO. <http://marine.rutgers.edu/mrs/LEO/LEO15.html> (accessed November 4, 2006).

National Geographic Society. Crittercam Chronicles. <http://www.nationalgeographic.com/crittercam/> (accessed November 4, 2006).

Sandwell, David T., Walter H. F. Smith. Exploring the Ocean Basins with Satellite Altimeter Data. July 26, 2006. <http://www.ngdc.noaa.gov/mgg/bathymetry/predicted/explore.HTML> (accessed November 4, 2006).

Gillian S. Holmes

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