At the Abyss by Thomas Reed

Author:Thomas Reed
Language: eng
Format: epub
Tags: History
ISBN: 9780307414625
Publisher: Random House Publishing Group
Published: 2007-12-17T16:00:00+00:00

TALKING TO SUBMARINES

In 1960, America’s first ballistic-missile-firing submarine, the George Washington, put to sea. 39 By 1975 over half of our strategic nuclear warheads were aboard a fleet of nuclear-powered Poseidon boats on patrol throughout the North Atlantic and Pacific Oceans as well as the Mediterranean Sea. That development was a great step toward stability in times of crisis. These warships were virtually undetectable while submerged, and thus virtually immune to surprise attack.

The Soviets did not enjoy a similar immunity. Their early submarines were noisy and thus easy for American technology to track. Throughout much of the 1960s most Soviet SSBNs heading out on patrol were identified by underwater sensors, by silent U.S. Navy attack submarines, and by airborne P-3 aircraft dropping sonobuoys. This tracking capability became more difficult to maintain in the 1970s when the Walkers, Navy radiomen father and son, gave away the game to the Soviets. At the same time, the Japanese sold the Soviets the technology to mill much quieter submarine propellers.

A quiet underwater fleet may be a good thing in some respects, but if one cannot detect or track a submarine, neither can one communicate with it. Keeping control of the submarine fleet, especially when it acquired nuclear arms, became a serious challenge.

Saltwater is a good conductor of electricity; it readily absorbs electromagnetic radiation. The degree of that absorption is a function of the incoming radiation’s frequency; very high frequency radar and radio signals cannot penetrate seawater at all. As a result, the submarines of World War II and immediately thereafter had to surface if they were to communicate. Those diesel-powered boats would deploy their HF (shortwave) antennae at night, from the surface or from snorkel depth, while recharging their batteries. But with the advent of more sophisticated adversaries, sitting atop the water or deploying a snorkel was too risky. Besides, HF transmission could easily be intercepted, would give away a submarine’s location, and was too unreliable.

The coming of nuclear power rendered the need to surface obsolete. To communicate with submarines only a few feet below the surface, but invisible to radar or an observer’s eye, the nuclear navies turned to Very Low Frequency communication systems. These transmitters operated in the three to thirty kilohertz range, resulting in a low data rate and requiring long receiving antennae at sea, 40 but those VLF signals could penetrate a few feet of seawater half a world away. VLF became the standard for both Soviet and U.S. Navy communication with their nuclear submarines.

As Soviet search technology became better, however, the Navy wanted to patrol at greater depths. Studies showed that transmitters operating at Extremely Low Frequencies (ELF, forty to eighty hertz) could communicate with deeply submerged boats. The data rate would be very slow and the required antenna huge, but the game was worth the candle. Using an ELF communication system, the nation’s strategic deterrent could remain truly undetectable, yet its payload of nuclear death and destruction would stay under the continuous and effective control of the National Command Authorities.

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