To the Depths in Trieste

Photo courtesy of the U.S. Navy

Interior of the Trieste

In 1960, Swiss scientist Jacques Piccard (above in this photo) and Navy lieutenant Donald Walsh made history when they descended in the U.S. Navy bathyscaphe Trieste to the bottom of the Mariana Trench. The brave divers were housed in a sphere attached to the bottom of the bathyscaphe's long buoyant tank.

The deep-diving research bathyscaphe Trieste was first launched in 1953 near Naples, Italy, by the Swiss scientist who designed her, Auguste Piccard. After several years of operations in the Mediterranean, she was purchased by the U.S. Navy and transported to San Diego, California. On October 2, 1959, Trieste was loaded onto the freighter Santa Maria for transport to the Mariana Islands for a series of deep-submergence operations in the Pacific Ocean, into the Challenger Deep, the deepest spot in the ocean identified by the British ship Challenger II in 1851. The operations were code-named "Project Nekton."

On January 23, 1960 — the day of Trieste's historic dive to the bottom of the Mariana Trench — the waves were 5 to 6 feet high in the ocean when Jacques Piccard (Auguste's son), and Navy Lt. Donald Walsh boarded Trieste from a rubber raft. They were housed in the white sphere at the bottom of the vessel. Reportedly, it was so packed with equipment that there was barely room for the men to sit in.

The Department of the Navy described Trieste as "the underwater equivalent of a lighter-than-air craft, much like a blimp operating in reverse. It consists of a 50-foot hull, 12 feet in diameter, filled with gasoline to make it buoyant, since gasoline is lighter than water. Beneath this hull is suspended a sphere 6.5 feet in diameter, which easily holds two men and scientific equipment."

Trieste had weights (9 tons of iron shot) to help it descend to the deepest point on the seafloor. The bathyscaphe's air tanks also were flooded with seawater to help make it sink. Trieste descended at a rate of 3 feet per second until it reached a depth of 27,000 feet, when its operators put on the brakes to slow its descent to half that rate.

The nearly 7-mile descent to the deepest known point on Earth took 4 hours and 48 minutes. Piccard and Walsh stayed on the bottom for 20 minutes, eating chocolate bars for sustenance, their teeth chattering in the 45°F cold cabin. Outside the bathyscaphe, the ocean temperature was 37.4°F. The mercury-vapor lamps on Trieste were the first to shine a light in this deep, dark place, illuminating a small, red shrimp-like creature and proving that the deep ocean had enough oxygen to support marine life.


These men were among the team responsible for the Trieste's design and operation. Photo courtesy of the U.S. Navy

At a depth of nearly 7 miles, the pressure is crushing, exceeding 16,883 pounds per square inch (more than a thousand times greater than the pressure at sea level). During the dive, an outer Plexiglas window cracked, which fortunately did not cause any problems other than some anxiety for the divers! They released two tons of iron shot to begin their ascent to the surface. The return trip took three hours and 17 minutes. When Piccard and Walsh surfaced, they officially entered the world record books.

A press release issued later in the day by the U.S. Department of Navy noted that "the purpose of today's dive is to demonstrate that the United States now possesses the capability for manned exploration of the sea down to the deepest part of its floor." The vessel was part of Project Nekton operations designed "to gather scientific knowledge of sunlight penetration, underwater visibility, transmission of manmade sounds, and marine geological studies of the trench." The ships USS Lewis and USS Wandank assisted Trieste on the mission.

In 1963, Trieste went to the Atlantic Ocean to search for the lost submarine USS Thresher (SSN-593). Trieste was taken out of service soon after completing that mission and is now housed at the Navy Museum, at the Washington Navy Yard, Washington, DC.

General arrangement drawing of Trieste, ca 1959. Photo courtesy of the U.S. Navy

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