War of the Whales (10 page)

5

In the Silent Service

As Balcomb soon discovered, everything about Navy sonar was cloaked in secrecy. Classes at Fleet Sonar School were held inside a windowless cinder-block building shuttered behind a large green security door—perhaps to prepare the student for the bunkerlike sonar stations where they’ d be working. The curriculum was a rigorous course load of acoustics, physics, sonar, and antisubmarine warfare history and tactics. Less than half the class passed. Balcomb loved it. The math and physics of underwater acoustics came easily to him. Learning the secret science of sound in the ocean made him feel like the sorcerer’s apprentice.

The best-kept military secret of the Cold War was the Sound Surveillance System, called SOSUS for short, that Balcomb was being trained to operate in the Pacific. SOSUS was a radical innovation in antisubmarine warfare that enabled the US Navy to maintain a crucial tactical advantage over the Soviets for 25 years.

•  •  •

At the end of the nineteenth century, US Navy strategist Admiral Alfred Mahan proclaimed, “Whoever rules the waves, rules the world.” Early in the twentieth century, the submarine quickly emerged as the preeminent naval weapon, trumping surface-based battleships that had ruled the seas for centuries.

The Germans became the world’s most lethal submariners. During World War II, “wolf packs” of German U-boats sank more than 3,000 Allied ships and were neutralized only late in the war when the Allies finally cracked the code of their radio transmissions. After the fall of Berlin in May 1945, Soviet and American naval commanders scrambled for the spoils of war. They seized German U-boats—as well as the German engineers who designed them—in hopes of gaining an edge in the next generation of submarine development.

Just before the war ended, the Germans had launched the fastest, most stealthy submarine ever built. The Soviets adopted the German quiet-diesel designs and moved aggressively to produce an armada of snorkeling submarines that could stay submerged for days, making them almost impossible to detect by visual or radar surveillance.
¹
By the early fifties, Soviet production lines were cranking out these vessels by the dozens each year. Due to the budgetary politics of peacetime, the US Navy knew that it couldn’t match Stalin’s resolve to produce submarines at a wartime pace. Over the course of the Cold War, the Soviets built almost four times as many submarines as the Americans.
²
The US Navy resolved to overcome its numerical disadvantage by excelling at acoustic warfare.

The traditional way to locate a submarine with sound was
active sonar
. First invented in 1912 in response to the
Titanic
disaster, the “echo-ranger” that enabled ships to locate submerged icebergs was soon repurposed to track the deadly U-boats unleashed by Germany in the first months of World War I. Active sonar locates submarines the same way bats and toothed whales use echolocation to hunt their prey—by sending out a sound signal and calculating the time and trajectory of the echo to fix the location of the target.

But WWII-era active sonar had a serious limitation: it could only detect submerged submarines at short ranges of a mile or less. During the Cold War, America needed to track a vast Soviet fleet of submarines across wide ocean basins.

Throughout the 1950s, both the United States and the Soviets raced to transform their submarines from fearsome stealth vessels into truly apocalyptic weapons of mass destruction. In 1955 the Soviets deployed the first submarine capable of launching nuclear-armed, ballistic missiles. The Americans soon followed suit. By the end of the decade, both navies had equipped their nuclear-armed subs with nuclear-powered turbines that enabled them to stay submerged for months. Unlike land and air-based ballistic missile systems, submarines were invisible and ever-moving missile silos that could hide and launch from anywhere in the world’s oceans—even under the Arctic ice cap.

Faced with the threat of intercontinental ballistic missiles launched from thousands of miles away, the question driving US antisubmarine strategy became: How can we detect and track Soviet submarines
across whole ocean basins
?

The answer was simple in concept and wildly ambitious in scope. If—as hypothesized by one of its physicists—the Navy could discover and exploit a hidden whispering chamber that extended throughout the deep ocean, then it could wiretap the world’s oceans and track the movements of every submarine in the Soviet fleet. SOSUS marked the beginning of a bold new era in sound surveillance:
passive sonar
. Instead of sending out an active sound signal and hoping to hear an echo, SOSUS’ passive sonar simply listened—intently and silently—for whatever sound a submarine or its propeller made as it moved through the water.

It all began in the spring of 1944, while the Allies were still battling German U-boats in the North Atlantic. A geophysicist working at Woods Hole Oceanographic Institution, Maurice Ewing, and his graduate student J. Lamar Worzel, sailed aboard the research vessel USS
Saluda
to the Bahamian island of Eleuthera. Their mission was to discover a hidden sound pipeline that Ewing was convinced lay deep beneath the ocean surface.

Ewing theorized that low-frequency sound waves, which were known to travel farther with less absorption in water than higher-frequency waves, could be transmitted across great distances in the deep ocean. He deduced that several thousand feet below the ocean surface, the intense pressure and cold temperature combine to create a distinct layer of water—a whispering chamber of sorts—that traps and focuses sound. Any sound that descended into what Ewing called the “deep sound channel” would travel horizontally for hundreds or even thousands of miles without diffusion or distortion, as if inside a sound pipeline.

Ewing’s hypothesis was based on the first principle of underwater sound that Balcomb learned in Fleet Sonar School: “Sound is lazy.” Meaning, sound waves always refract toward the slowest sound layer in the water column. Since sound accelerates in warmer water, it refracts away from the heated surface layer toward the slower, colder water below. Eventually, at approximately 3,000 feet, the increasing pressure at depth compresses and speeds the sound up again, refracting it upward toward the slower, lower-pressure water near the surface. Ewing hypothesized that the deep sound channel would attract and trap “lazy” sound waves into this deep ocean layer, and then transmit the sound signal horizontally through this sound channel, more or less indefinitely.

To test this theory, Ewing directed his escort vessel, the destroyer USS
Buckley
, to drop four-pound bombs timed to detonate 3,000 feet below the surface—explosives being the high-decibel, low-frequency sound source of choice for Ewing and his generation of acoustic experimenters. Detonating explosives at deep-sea pressures of 8,000 pounds per square inch was considered impossible by most physicists. But Worzel, the inventive engineer in their partnership, packed the explosives into automobile inner tubes and jury-rigged a detonator using paper caps from toy pistols.

Ewing suspended an underwater microphone, called a hydrophone, over the bow of the
Saluda
to a depth of 3,000 feet. After each detonation, the
Buckley
moved ten miles farther into the Atlantic and detonated another bomb. When the
Buckley
ran out of bombs, 900 miles out to sea, Ewing could still hear the explosions clearly from the
Saluda
, with almost no signal loss! He happily set sail for Woods Hole to announce that his hypothesis of a deep sound channel was now fact.
³

To measure the outer limits of sound propagation in the deep sound channel, Ewing asked a favor of a colleague who was flying to Dakar, West Africa, aboard a military transport plane. Ewing gave his colleague a suitcase full of time-delayed hand grenades and asked him to drop one from the plane every hour during the Atlantic crossing. (As it happened, the only way to drop bombs from a transport plane was by flushing them down the toilet.) When the last grenade was flushed into the sky and detonated, as intended, in the deep ocean just off the coast of Africa, Ewing could hear the explosion from aboard the
Saluda
, 6,000 miles to the west in the Bahamas. He’ d proven that the deep sound channel could transmit sound across an entire ocean basin, even across the underwater mid-Atlantic mountain range. (In 1960 Ewing replicated this experiment across
two
oceans by dropping depth charges off Perth, Australia, and recording the explosion four hours later and 12,000 miles to the west in Bermuda.)

Ewing’s ambition was to use the deep sound channel (which he renamed the sound fixing and ranging, or SOFAR, channel) to triangulate the location of a downed pilot in the open ocean.
⁴
Ewing’s pilot rescue system was successfully built and deployed briefly in the Pacific after the war, but the game-changing impact of the deep sound channel was on long-range submarine detection.

In 1949 Ewing and Worzel set up the first demonstration SOSUS listening station, a deep-water hydrophone five miles offshore from Bermuda. Connected to the shore by 25,000 feet of armored cable, their hydrophone could detect and track a snorkeling diesel sub at 500 miles.

Beginning in 1951, the Office of Naval Research recruited both academic and private sector partners to construct the initial SOSUS network throughout the Caribbean, code-named Project Caesar. Woods Hole researchers surveyed the ocean bottom and selected the optimal locations to anchor the hydrophone arrays, while American Telephone and Telegraph (AT&T) lay telephone cable connecting the hydrophones to the shore-based Navy listening stations.

In 1954 the Navy launched Project Jezebel to wiretap the entire Eastern Seaboard. The Massachusetts Institute of Technology, Columbia University, and Bell Labs installed SOSUS arrays of 40 high-fidelity hydrophones—each 1,000 feet wide—across the deep sea floor and connected by cable to shore-based listening stations in Cape Hatteras, Delaware, Nantucket, Newfoundland, Nova Scotia, and Iceland.

SOSUS was fully operational in the Atlantic by 1955, and in 1960 it tracked the first US submarine armed with a nuclear missile, the
George Washington
, as it made its maiden voyage across the Atlantic. Two years later, during the Cuban Missile Crisis, SOSUS picked up four Soviet Foxtrot submarines as they passed through the United Kingdom–Iceland gap and tracked them to within 100 miles of the coast of Florida, where two US destroyers forced the subs to the surface.

In the 1960s, the Navy expanded the SOSUS network to the Pacific, building listening stations that stretched from Alaska and Vancouver Island to Washington, Oregon, and California, with forward stations in Hawaii and Midway Island.

By the end of the 1960s, when Ken Balcomb was assigned as Oceanographic Officer to his first SOSUS station in the Pacific Northwest, the Navy had installed a multi-ocean burglar alarm system manned by 2,200 personnel and connected by 30,000 miles of telephone cable to centralized control stations in Norfolk and Pearl Harbor. With trip wires at every conceivable choke point heading in and out of the Pacific and Atlantic, the US Navy could track every Soviet submarine at sea, from nuclear-powered, nuclear-armed “boomers” to diesel-engine attack subs. Most remarkable of all, the Navy had managed to keep this massive construction and installation project a secret.

The Pacific Beach SOSUS station was housed inside a windowless concrete bunker at a secured coastal base. Hydrophone feeds from across the North Pacific were broadcast from speakers in the main listening room, which was the size of a large basketball gymnasium. A hundred men stood beside row upon row of sound-analyzer consoles where a hot stylus burned black and gray images onto rolls of heat-sensitive paper.
⁵

The first thing that hit Balcomb when he came through the cipher-locked double doors to begin his shift each morning was the smell of ozone and burning carbon. No matter how much air-conditioning and filtering were deployed, a haze of fine carbon dust still hung in the air, glinting in the bright fluorescent lights.

The low-frequency sound analyzer that generated the audiograms of the Soviet submarines was the brainchild of Bell Laboratories. Based on the human voiceprints Bell had developed for its telephone business, the sound analyzer created a visual graph of the low-frequency signals transmitted from SOSUS hydrophones anchored hundreds of miles offshore. The sound sources, such as engine noise from Soviet submarines, originated thousands of miles farther offshore, transmitted to the hydrophones via the deep sound channel.

Lieutenant Balcomb managed the station’s sonar technicians and worked with neighboring SOSUS stations to track the Soviet fleet across the wide Pacific basin. He assessed the incoming audiograms and audiotapes in search of a target. It was more art than science, relying on interpretive skills he honed over thousands of hours of analysis.

Balcomb’s task was to identify the sound signature of Soviet submarines based on the low-frequency noise and vibration from their turbines. The Soviets’ Delta-class submarines were nicknamed boomers because they were 500 feet long and armed with nuclear ballistic missiles. With their nuclear-powered steam turbines, the Deltas could stay submerged for months at a time, rendering them invisible to radar, aircraft, and satellites. But their turbines were much noisier than American boomers, making them relatively easy to track through the deep sound channel using SOSUS hydrophones. The diesel-powered “hunter-killer” attack subs were less than half the size of boomers, and armed with torpedoes rather than missiles. They were quieter and harder to track acoustically, except when charging their batteries.
⁶

There were a host of other, more subtle sounds emanating from submarines that SOSUS operators like Balcomb became expert at detecting: noise from propeller shafts, gears, pumps, electric motors, hull vibration—even the sound of water flowing past the submarine hull. Taken together, these sounds comprised an acoustic signature as individual as a human fingerprint. SOSUS operators were constantly compiling and updating a database of sound signatures for Soviet submarines—not just by class and type, but for individual submarines within each class. As successive generations of Soviet subs gradually became quieter, the US Navy continually improved its signal processing software to maintain its acoustic advantage.