Deep-sea exploration

The submersible's manipulator arm collecting a crab trap containing five galatheid crabs. This is an eel trap that has been modified to better catch deep sea fauna. Life on the Edge 2005 Expedition.

Deep-sea exploration is the investigation of physical, chemical, and biological conditions on the sea bed, for scientific or commercial purposes. Deep-sea exploration is considered as a relatively recent human activity compared to the other areas of geophysical research, as the depths of the sea have been investigated only during comparatively recent years. The ocean depths still remain as a largely unexplored part of the planet, and form a relatively undiscovered domain.

In general, modern scientific Deep-sea exploration can be said to have begun when French scientist Pierre Simon de Laplace investigated the average depth of the Atlantic ocean by observing tidal motions registered on Brazilian and African coasts. He calculated the depth to be 3,962 m (13,000 ft), a value later proven quite accurate by soundings measurement.[1] Later on, with increasing demand for submarine cables installment, accurate soundings was required and the first investigations of the sea bottom were undertaken. First deep-sea life forms were discovered in 1864 when Norwegian researchers obtained a sample of a stalked crinoid at a depth of 3,109 m (10,200 ft). The British Government sent out the Challenger expedition (a ship called the HMS Challenger) in 1872 which discovered 715 new genera and 4,417 new species of marine organisms over the space of 4 years.[1]

The first instrument used for deep-sea investigation was the sounding weight, used by British explorer Sir James Clark Ross.[2] With this instrument, he reached a depth of 3,700 m (12,140 ft) in 1840.[3] The Challenger expedition used similar instruments called Baillie sounding machines to extract samples from the sea bed.[4]

Teleoperated Robotics is one of the safest way to explore deep waters: a remotely operated robot vehicle (ROV) becomes the divers eyes and hands in deep marine environments. Decompression sickness ('the bends') can occur if a diver surfaces too quickly from extreme depths; nitrogen in the blood will come out of solution during rapid ascent, and can cause serious injury or death. Using teleoperated robotics or Atmospheric Diving Suits (ADS), which are human shaped (anthropomorphic) submarine exoskeletons, provide a relatively safe method of exploration, with the disadvantage that the lack of fine motor control limits how much of the environment can be closely examined. Bhargav Gajjar of Vishwa Robotics and Massachusetts Institute of Technology, with funding from the Office of Naval Research of the US Navy, is conducting research into deep-sea manipulators in an effort to create a more sensitive system for deep-sea work. This technological breakthrough is a major milestone in human exploration of the last frontier.[5]

In 1960, Jacques Piccard and US Navy Lieutenant Donald Walsh descended in the bathyscaphe Trieste into the Mariana Trench, the deepest part of the world's oceans, to make the deepest dive in history: 10,915 meters (35,810 ft).[6] On 25 March 2012, filmmaker James Cameron descended into the Mariana Trench and, for the first time, is expected to have filmed and sampled the bottom.[7][8][9][10][11]

History

Throughout history, scientists have relied on a number of instruments to measure, map, and observe the ocean's depths. One of the first instruments used to examine the seafloor was the sounding weight. Ancient Viking sailors took measurements of sea depth and sampled seafloor sediments with this instrument, which consisted of a lead weight with a hollow bottom attached to a line. Once the weight reached the sea bottom and collected a sample of the seabed, the line was hauled back on board ship and measured in fathom.[12] Cornelius Drebbel, a Dutch architect, is generally given credit for construction of the first submarine. His submersible boat consisted of a wooden frame sheathed in animal skin. Oars, with its openings were sealed with tight-fitting leather flaps, extended out the sides to propel the craft through the water, at depths up to 4.6 metres (15 ft). Drebel tested his submarine in the Thames River in England in sometime between 1620 and 1624. It is believed that King James I enjoyed a short ride in the craft.[13]

However, the nature of the deep ocean remained an unrevealed mystery until the mid-19th century. Scientists and artists alike imagined the deep sea as a lifeless soup of placid water. French author Jules Verne, who helped pioneer the science-fiction genre, portrayed the deep ocean as contained in a bowl of static rock in his “Twenty Thousand Leagues under the Sea”. By the late 1860s, controversial modern scientific theories, the origin of life by evolution and the enormity of geologic time had created a foundation of scientific curiosity and provoked a rising interest in marine exploration. The Royal Society of England thus initiated an ambitious oceanographic mission to expand a scarce collection of existing marine data that included Charles Darwin's observations during the voyage of the HMS Beagle (1831–1836), a bathymetric chart created by U.S. Navy Lt. Matthew Maury to aid installation of the first trans-continent telegraph cables in 1858, and a few examples of deep marine creatures.[14]

From 1872 to 1876, a landmark ocean study was carried out by British scientists aboard HMS Challenger, a sailing vessel that was redesigned into a laboratory ship. The HMS Challenger expedition covered 127,653 km (68,890 nautical miles), and shipboard scientists collected hundreds of samples, hydrographic measurements, and specimens of marine life. They are also credited with providing the first real view of major seafloor features such as the deep ocean basins. They discovered more than 4,700 new species of marine life, including deep-sea organisms.[15]

Deep-sea exploration advanced considerably in the 1900s thanks to a series of technological inventions, ranging from sonar system to detect the presence of objects underwater through the use of sound to manned deep-diving submersibles such as DSV Alvin. Operated by the Woods Hole Oceanographic Institution, Alvin is designed to carry a crew of three people to depths of 4,000 meters (13,124 ft). The submarine is equipped with lights, cameras, computers, and highly maneuverable robotic arms for collecting samples in the darkness of the ocean's depths.[16]

However, the voyage to the ocean bottom is still a challenging experience. Scientists are working to find ways to study this extreme environment from the shipboard. With more sophisticated use of fiber optics, satellites, and remote-control robots, scientists one day may explore the deep sea from a computer screen on the deck rather than out of a porthole.[15]

Milestones of deep sea exploration

The extreme conditions in the deep sea require elaborate methods and technologies, which has been the main reason why its exploration has a comparatively short history. In the following, important key stones of deep sea exploration are listed.

Oceanographic instrumentation[2]

Deep sea exploration apparatus,1910

The sounding weight, one of the first instruments used for the sea bottom investigation, was designed as a tube on the base which forced the seabed in when it hit the bottom of the ocean. British explorer Sir James Clark Ross fully employed this instrument to reach a depth of 3,700 m (12,140 ft) in 1840.[2][19]

The sounding weights used on the HMS Challenger were slightly advanced called "Baillie sounding machine". The British researchers used wire-line soundings to investigate sea depths and collected hundreds of biological samples from all the oceans except the Arctic. Also used on the HMS Challenger were dredges and scoops, suspended on ropes, with which samples of the sediment and biological specimens of the seabed could be obtained.[2]

A more advanced version of the sounding weight is the gravity corer. The gravity corer allows researchers to sample and study sediment layers at the bottom of oceans. The corer consists of an open-ended tube with a lead weight and a trigger mechanism that releases the corer from its suspension cable when the corer is lowered over the seabed and a small weight touches the ground. The corer falls into the seabed and penetrates it to a depth of up to 10 m (33 ft). By lifting the corer, a long, cylindrical sample is extracted in which the structure of the seabed’s layers of sediment is preserved. Recovering sediment cores allows scientists to see the presence or absence of specific fossils in the mud that may indicate climate patterns at times in the past, such as during the ice ages. Samples of deeper layers can be obtained with a corer mounted in a drill. The drilling vessel JOIDES Resolution is equipped to extract cores from depths of as much as 1,500 m (4900 ft) below the ocean bottom. (See Ocean Drilling Program)[12][20]

Echo-sounding instruments have also been widely used to determine the depth of the sea bottom since World War II. This instrument is used primarily for determining the depth of water by means of an acoustic echo. A pulse of sound sent from the ship is reflected from the sea bottom back to the ship, the interval of time between transmission and reception being proportional to the depth of the water. By registering the time lapses between outgoing and returning signals continuously on paper tape, a continuous mapping of the seabed is obtained. The majority of the ocean floor has been mapped in this way.[21]

In addition, high-resolution television cameras, thermometers, pressure meters, and seismographs are other notable instruments for deep-sea exploration invented by the technological advance. These instruments are either lowered to the sea bottom by long cables or directly attached to submersible buoys. Deep-sea currents can be studied by floats carrying an ultrasonic sound device so that their movements can be tracked from aboard the research vessel. Such vessels themselves are equipped with state -of-art navigational instruments, such as satellite navigation systems, and global positioning systems that keep the vessel in a live position relative to a sonar beacon on the bottom of the ocean.[2]

Oceanographic submersibles

Because of the high pressure, the depth to which a diver can descend without special equipment is limited. The deepest recorded made by a skin diver is 127 meters (417 ft).[15] Revolutionary new diving suits, such as the "JIM suit," allows divers to reach depths up to approximately 600 meters (2,000 ft).[22] Some additional suits feature thruster packs that boost a diver to different locations underwater.[23]

To explore even deeper depths, deep-sea explorers must rely on specially constructed steel chambers to protect them. The American explorer William Beebe, also a naturalist from Columbia University in New York, was the designer of the first practical bathysphere to observe marine species at depths that could not be reached by a diver.[24] The Bathysphere, a spherical steel vessel, was designed by Beebe and his fellow engineer Otis Barton, an engineer at Harvard University.[25] In 1930 Beebe and Barton reached a depth of 435 m (about 1425 ft), and 923 m (3028 ft) in 1934. The potential danger was that if the cable broke, the occupants could not return to the surface. During the dive, Beebe peered out of a porthole and reported his observations by telephone to Barton who was on the surface.[19][26]

In 1948, Swiss physicist Auguste Piccard tested a much deeper-diving vessel he invented called the bathyscaphe, a navigable deep-sea vessel with its gasoline-filled float and suspended chamber or gondola of spherical steel.[24] On an experimental dive in the Cape Verde Islands, his bathyscaphe successfully withstood the pressure on it at 1,402 meters (4,600 ft), but its body was severely damaged by heavy waves after the dive. In 1954, with this bathyscaphe, Piccard reached a depth of 4,000 m (13,125 ft).[24] In 1953, his son Jacques Piccard joined in building new and improved bathyscaphe Trieste, which dived to 3,139 meters (10,300 ft) in field trials.[24] The U.S. Navy acquired Trieste in 1958 and equipped it with a new cabin to enable it to reach deep ocean trenches.[6] In 1960, Jacques Piccard and Navy Lieutenant Donald Walsh descended in Trieste to the deepest known point on Earth - the Challenger Deep in the Mariana Trench, successfully making the deepest dive in history: 10,915 meters (35,810 ft).[6]

An increasing number of occupied submersibles are now employed around the world. The American-built DSV Alvin that is operated by the Woods Hole Oceanographic Institution, is a three-person submarine that can dive to about 3,600 m (12,000 ft) and is equipped with a mechanical manipulator to collect bottom samples.[27] Alvin made its first test dive in 1964, and has performed more than 3,000 dives to average depths of 1,829 meters (6,000 ft). Alvin has also involved in a wide variety of research projects, such as one where giant tube worms were discovered on the Pacific Ocean floor near the Galápagos Islands.[27]

Unmanned Submersibles

Describing the operation and use of autonomous landers in deep sea research.

One of the first unmanned deep sea vehicles was developed by the University of California with a grant from the Allan Hancock Foundation in the early 1950s to develop a more economical method of taking photos miles under the sea with an unmanned steel high pressure 3,000 lb sphere called a benthograph which contained a camera and strobe light. The original benthograph built by USC was very successful in taking a series of underwater photos until it became wedged between some rocks and could not be retrieved.[28]

ROVs, or Remote Operated Vehicles, are seeing increasing use in underwater exploration. These submersibles are piloted through a cable which connects to the surface ship, and they can reach depths of up to 6,000 meters. New developments in robotics have also led to the creation of AUVs, or Autonomous Underwater Vehicles. The robotic submarines are programmed in advance, and receive no instruction from the surface. HROV combine features of both ROVs and AUV, operating independently or with a cable.[29][30] Argo was employed in 1985 to locate the wreck of the RMS Titanic; the smaller Jason was also used to explore the ship wreck.[30]

Scientific results

In 1974, the Alvin (operated by the Woods Hole Oceanographic Institution and the Deep Sea Place Research Center), the French bathyscaphe Archimède, and the French diving saucer Cyane, assisted by support ships and the Glomar Challenger, explored the great rift valley of the Mid-Atlantic Ridge, southwest of the Azores. About 5,200 photographs of the region were taken, and samples of relatively young solidified magma were found on each side of the central fissure of the rift valley, giving additional proof that the seafloor spreads at this site at a rate of about 2.5 cm (about 1 in) per year (see plate tectonics,).[31]

In a series of dives conducted between 1979–1980 into the Galápagos rift, off the coast of Ecuador, French,Italian, Mexican, and U.S. scientists found vents, nearly 9 m (nearly 30 ft) high and about 3.7 m (about 12 ft) across, discharging a mixture of hot water (up to 300 °C/570 °F) and dissolved metals in dark, smoke-like plumes (see hydrothermal vent,). These hot springs play an important role in the formation of deposits that are enriched in copper, nickel, cadmium, chromium, and uranium.[31][32]

See also

References

  1. 1 2 Deep Sea Exploration." World of Earth Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Gale Cengage, 2003. eNotes.com. 2006. 7 Dec, 2009 <http://www.enotes.com/earth-science/deep-sea-exploration>
  2. 1 2 3 4 5 Archived May 1, 2009, at the Wayback Machine.
  3. ↑ "DEEP-SEA EXPLORATION (2009)". History.com. Retrieved 8 December 2009.
  4. ↑ "Underwater Exploration - Oceanography". jrank.org.
  5. ↑ Popular Science:Robotic hands let divers grasp and prod
  6. 1 2 3 "Jacques Piccard: Oceanographer and pioneer of deep-sea exploration - Obituaries, News". London: The Independent. 2008-11-05. Retrieved 2010-09-17.
  7. ↑ Than, Ker (25 March 2012). "James Cameron Completes Record-Breaking Mariana Trench Dive". National Geographic Society. Retrieved 25 March 2012.
  8. ↑ Broad, William J. (25 March 2012). "Filmmaker in Submarine Voyages to Bottom of Sea". New York Times. Retrieved 25 March 2012.
  9. ↑ AP Staff (25 March 2012). "James Cameron has reached deepest spot on Earth". MSNBC. Retrieved 25 March 2012.
  10. ↑ Broad, William J. (8 March 2012). "Miles Under the Pacific, a Director Will Take On His Most Risky Project". NYTimes. Retrieved 8 March 2012.
  11. ↑ Staff (7 March 2012). "DEEPSEA CHALLENGE – National Geographic Explorer James Cameron’s Expedition". National Geographic Society. Retrieved 8 March 2012.
  12. 1 2 "Deep-sea exploration: Earth's final frontier: only a portion of the potential of the oceans has been tapped, but it is clear that exploring and improving our understanding of the ocean and its influence on global events are among our most important challenges today. | Goliath Business News". Goliath.ecnext.com. Retrieved 2010-09-17.
  13. ↑ ":: The Origins of Submarines ::". Boulderinternetguide.com. 1955-01-17. Retrieved 2010-09-17.
  14. ↑ "Deep Sea Exploration." World of Earth Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Gale Cengage, 2003. eNotes.com. 2006. 9 Dec, 2009 <http://www.enotes.com/earth-science/ deep-sea-exploration>
  15. 1 2 3 "A Brief History". Ceoe.udel.edu. Retrieved 2010-09-17.
  16. ↑ "Human Occupied Vehicle Alvin : Woods Hole Oceanographic Institution". Whoi.edu. Retrieved 2010-09-17.
  17. ↑ "The Ocean Floor". scholastic.com.
  18. ↑ Ludwig Darmstaedter (Hrsg.): Handbuch zur Geschichte der Naturwissenschaften und der Technik, Springer, Berlin 1908, S. 521
  19. 1 2 Deep-Sea Exploration: Earth's Final Frontier Only a Portion of the Potential of the Oceans Has Been Tapped, but It Is Clear That Exploring and Improving Our Understanding of the Ocean and Its Influence on Global Events Are among Our Most Important Challenges Today Journal article by Stephen L. Baird; The Technology Teacher, Vol. 65, 2005.
  20. ↑ "WHOI : Instruments : Gravity Corer". Whoi.edu. Retrieved 2010-09-17.
  21. ↑ "echo sounder: Definition from". Answers.com. Retrieved 2010-09-17.
  22. ↑ Office of Communications and Marketing (2004-10-30). "Depths of Discovery". Expeditions.udel.edu. Retrieved 2010-09-17.
  23. ↑ Archived April 17, 2009, at the Wayback Machine.
  24. 1 2 3 4 "Underwater Exploration - History, Oceanography, Instrumentation, Diving Tools And Techniques, Deep-sea Submersible Vessels, Key Findings In Underwater Exploration - Deep-sea pioneers". Science.jrank.org. 1960-01-23. Retrieved 2010-09-17.
  25. ↑ "Bathysphere - Air, Sea, Exploration, Diving, Bell, and Scientists". Science.jrank.org. 1930-06-06. Retrieved 2010-09-17.
  26. ↑ "Deep Sea Explore" (PDF). Productivitydevelopment.com. Retrieved 15 May 2015.
  27. 1 2 TechTalk. "Deep sea exploration and marine science aboard Alvin et al - 11/04". Sciencebase.com. Retrieved 2010-09-17.
  28. ↑ "Deep Sea Photographers." Popular Mechanics, January 1953, p. 105.
  29. ↑ The Ocean Portal Team (24 July 2012). "The Deep Sea". Smithsonian Ocean Portal.
  30. 1 2 "Robert Ballard: Undersea Explorers". EnchantedLearning.com. Retrieved 2010-09-17.
  31. 1 2 Archived February 8, 2010, at the Wayback Machine.
  32. ↑ "Deep Sea Exploration: Submarine Volcanoes and Hydrothermal Vents". Floridasmart.com. Retrieved 2010-09-17.

External links

Wikisource has the text of the 1920 Encyclopedia Americana article Deep-Sea Exploration.
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