- The nuclear-powered submarine USS San Francisco was heading
toward Australia on Jan. 8 when it hit an underwater mountain not marked
on naval charts. The impact brought the sub to an almost instantaneous
stop, killing one crew member and seriously injuring 23 others.
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- The accident raises the question of why a state-of-the-art
vessel in the world's most powerful military was effectively operating
blind. The inner hull of the submarine was not breached, but one death
resulted. Why, with sonar and satellite scanning, is so little known about
the topography of the seabed?
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- An obvious answer is that there is simply a vast area
of underwater seascape to measure.
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- "Precision surveys only exist for less than 10 percent
of the world's oceans, usually well-traveled commercial routes," said
Capt. Jeffery Best of the Naval Oceanographic Office in south Mississippi.
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- To make matters worse, scanning techniques until recently
have been ineffective. "Most of the world's oceans are imprecisely
mapped, and depths from Captain Cook using lead lines are still used on
some charts," said Barbara Reed, director of the Naval Oceanographic
Office's hydrography department.
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- Incomplete and outdated charts seem to have been the
problem in the case of the San Francisco.
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- Since the accident, the submarine's commander has been
reassigned pending a full investigation, but officials at the National
Geospatial-Intelligence Agency in Bethesda, Maryland, revealed that the
seabed charts had not been updated since 1989. A blurry satellite image
of the accident site from 1999 gives only a suggestion of a submerged structure,
according to the agency -- it could just as easily be a plankton bloom
or an oil slick.
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- "What is needed is something that can turn the sea
transparent," said Chris Wooldridge, a marine geographer at the School
of Earth, Ocean and Planetary Sciences at Cardiff University in Wales.
And that is exactly what the latest software and hardware does.
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- Wooldridge is head of the CodaOctopus laboratory, which
opened Feb. 1. His team will use new technology to map extensive areas
off the coast of Wales to create a virtual-reality image, allowing scientists
to "walk" the seabed from the laboratory, or from aboard a vessel
offshore.
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- A central part of the new technology is the Echoscope.
Where conventional sonar uses one beam to build up a picture gradually,
Echoscope uses an array of more than 16,000 beams to create an instantaneous,
real-time image.
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- "It's like the difference between scanning a dark
room with only a pencil flashlight, and turning on the light," said
Paul Baxter, a spokesman for CodaOctopus in Deddington, England. "And
because Echoscope works in real time, we have, in effect, an acoustic camera."
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- With better mapping will come better understanding. Increased
information could improve the prediction of earthquakes, tsunamis and hurricane-induced
floods.
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- Apart from the vastness of the ocean and the outdated
charts, there is another reason why the topography of the seabed could
be poorly known: Some governments hang onto their information. How much
exchange of information is there?
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- "Countries are still playing the deep Cold War,
still deploying nuclear submarines with nuclear weapons," said Wooldridge.
"Subs use temperature and salinity as well as depth to hide, and some
of these details are classified."
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- However, Wooldridge said, information is still exchanged.
"It's of benefit to no one if a nuclear-powered submarine runs aground
in international waters."
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- The Naval Oceanographic Office agrees.
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- "Every country with a coastline has an economic
interest in making charts of shipping routes and their country's ports
available commercially," said Best. "The U.S. Navy has worked
cooperatively for many years with countries in their territorial waters
and assists many countries in developing their own surveying and charting
capability. Those countries, in turn, make their charts available."
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