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Sonar
in Underwater Warfare Technology
Sonar
is naturally produced by mammals is a means of communication, detection and
determines breeding patterns. Artificially produced sonar has gone a long way
since the development of sonar devices in the 1920s: it has gone from being a
useful form of detection and communication to a powerful tool in warfare
technology.
Since
WWII, ships have used passive sonar and hydrophones (Siegel, p.10 &
Williams, p.1). In the early 1980’s, the U.S Navy identified the new
generation of silent submarines as a national security threat (MRF, p.1) hence,
they have invested research for over a decade into low frequency active sonar (LFAS).
The loudest sound ever produced by man underwater, LFAS transmits at 100 –
1000 hertz equal to 215 – 230 dB with the ability to detect quiet submarines (ENS
p.2).
However,
using sonar technology can be dangerous as well as useful. As rock musicians
know, repeated exposure to repetitive moderate loud noise damages the ears. If
loud enough, it can rupture the ears, lungs and other human vibratory tissues as
sound exerts pressure. As the bodily tissues resonate with the sound frequency,
the pressure increases. Prolonged or repeated noise in humans disturbs sleep
patterns (Siegel, p.12, 13).
In
a U.S Navy study, scientists exposed a 32 -year old diver to LFAS at 160dB.
After 12 minutes, he experienced dizziness, drowsiness, memory dysfunction and
seizure. After two years, he is on anti-depressants and anti-seizure medications
(Cousteau p.2).
At
140 dB, whales change course and abandon their calves (Lazaroff p.2). Sonar
arrays generate sound pressure levels of up to 230dB in water near the source
and tactical sonar transmits at 235dB at a mid-range frequency of 3,500 –
7,500 hertz. Sound intensity increases 10 times over from 160db to 170dB. A
single source transmitter generates 215dB (Cousteau p.1, William p.2).
The
U.S Navy’s Surveillance Towed Array Sonar System (SURTASS) produces passive
sonar but with enhancements SURTASS can broadcast sounds so that the hydrophone
can listen for reflected sounds from submarines. With active sonar SURTASS can
detect the otherwise undetectable (Lazaroff #2 p.4). Though SURTASS is based in
Virginia, USA, it regularly operates from ports in Scotland, Spain, Japan, Pearl
Harbor, Hawaii and California (ENS p.3). When the Navy became ready to deploy
its LFAS system in 80% of the world’s oceans, the National Resources Defense
Council (NRDC) discovered the Navy was breaking the law. (MRF p.1). Lawsuits
filed in Honolulu in the late 1990’s were on the basis that the Navy spent
millions of dollars on a sonar system before completing an analysis or producing
an Environmental Impact Statement. (EIS).
During
the tests off Hawaii in 1998, vessel captains observed humpback whales leaving
the testing area and reported it to the National Marine Fisheries Service. One
snorkeler emerged with acute trauma having experienced a 120dB broadcast. (Lazaroff
#2 p.1, 5 ).
Following
another lawsuit filed this May, the U.S. Navy finally admitted to causing the
deaths of 17 marine mammals in the Bahamas last year. Their joint report with
the National Marine Fisheries Services concluded that the presence of whales in
a restrictive ocean channel. The calm waters reflected and amplified the sound,
which became concentrated in the upper 200 meters of ocean. Bubbles would
disperse sound broadcasts. Within 24 hours of intensive use of active mid-range
sonar when the naval ships were passing through the NE and the NW Providence
Channels with multiple sonar in use. Specimens from four dead whales revealed
internal bleeding of the ear and around the brain (Lazaroff #1 p.2).
In
addition to SURTASS the army has remote-control underwater vehicles equipped
with advanced sensors. Designed for navy SEALS, the function will be to
‘explore’ shallow waters pertaining to the Yellow Sea in SE Asia with
two-thirds shallow and the Persian Gulf three-quarters. Both are less than 180
feet. The army also plans to deploy LFAS arrays in the Atlantic and Pacific
Oceans (Williams p.2). These would allow for mine reconnaissance and collection
of tactical intelligence said Scott Farnsworth, the Navy’s deputy program
manager for unmanned underwater vehicles (UUV’s). With $25 million of the UUV
program funded by US Special Operations Command until 2004. Fourteen vehicles
are expected to be operational by February ’03. The remote mine-hunting system
alone weighs 14,000 pounds and carries forward-looking sonar and a towed sensor
of 1,000 pounds that carries a side-looking, a gap-filling and a forward looking
sonar (Erwin p.1 – 2).
If
necessity is the mother of invention, then fear is the soldier of destruction.
The world as one global village therefore through certain eyes must seem as one
huge national security threat. “Whoever joins himself (to another) in a good
cause shall have a fare share of it, and whoever joins himself (to another) in
an evil cause shall have the responsibility of it; and Allah controls all
things” (Surat ul Nisa 4:85)
Sources:
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