Bathyscaphe Trieste, the first vehicle to descend into the ocean depths of the Mariana Trench

The bathyscaphe Trieste was built in Italy between 1952 and 1953 based on a design by two Swiss engineers, Auguste and Jacques Piccard. It was composed of a main bodypartly filled with petrol (lighter than water), and with a steel ball to accommodate the crew. The Trieste operated in the Mediterranean until 1958, when she was purchased by the United States Navy and used for the descent into the Mariana Trench, at 10,916 meters of depth, which occurred on January 23, 1960 with protagonists Jacques Piccard And Donald Walsh.

In the following years the bathyscaphe was used for other missions, including the search for a sunken nuclear submarine, and in 1964 it was withdrawn from service. The technical characteristics of the Trieste were taken as a model for the construction of subsequent bathyscaphes, such as the Titan. Today it is exhibited at Washington Naval Museum.

What is a bathyscaphe

Bathyscaphes, self-propelled submersible units, are vehicles capable of diving to great depths. Normal submarines cannot descend more than a few hundred meters below sea level, because they are not capable of resist water pressure, which increases as you go down. Specific means are therefore necessary, which must be both resistant and capable of not sinking due to the weight. The first bathyscaphes were built after the Second World War by a Swiss engineer, August Piccard, who until then had worked on hot air balloons.

Auguste Piccard (credits Bundesarchiv)

Piccard thought of exploiting the same principle as balloons, that is, using a substance lighter than water (just as balloons use one that is lighter than air): petrol, which filled a large tank, to which a spherical cabin was connected to house the crew. Thus was born the first bathyscaphe, named FNRS2 (FNRS1 was a hot air balloon built by Piccard), which in 1954, after some modifications and after being renamed FNRS3, managed to descend to over 4000 meters of depth off the coast of Senegal.

Piccard and his son Jacques, in the meantime, had started another project.

The bathyscaphe Trieste: construction and technical characteristics

In 1952 the two engineers designed a new bathyscaphe. The main body, approximately 18 meters long and 3.5 meters wide, it contained petrol tanks and ballast made up of nine tons of iron pellets. A steel sphere was connected to the main body to house the crew: 12.7 cm thick, in order to be able to resist the pressure of the water at great depths, it had a diameter of 2.16 meters and could accommodate two people, who entered through a small corridor. A Plexiglas window in the shape of a truncated cone it allowed you to look outside and some special light bulbs, capable of withstanding a pressure greater than 1000 atmospheres, ensured the lighting of the surrounding environment.

Technical features

The bathyscaphe was entirely built in Italy: the main body in the Monfalcone shipyards, near Trieste, the sphere at the Acciaierie di Terni and the window at the Officine Galileo in Florence. It was then assembled at the Castellammare di Stabia shipyard, in the province of Naples. The bathyscaphe was called Trieste in homage to the city where the main body was built.

The descent of the bathyscaphe Trieste into the Mariana Trench

The bathyscaphe Trieste entered service in 1953. The first dive took place on August 16th near Capri and on the following September 30th the vehicle managed to descend into the Tyrrhenian Trench, off the island of Ponza, at approximately 3,150 meters deep. The bathyscaphe operated in the Mediterranean for four years, making numerous descents above 3,700 metres.

In 1958 Trieste was purchased by the US Navy, which replaced the steel sphere built in Terni with another cabin, produced by the German company Krupp. The American Navy intended to use the bathyscaphe for a feat never attempted before: bringing a human crew into theChallenger Abyss of the Mariana Trench, the deepest point on the planet, a 10,916 meters below sea level.

The undertaking was successfully completed on January 23, 1960. The Trieste, with Jacques Piccard and US naval officer Donald Walsh on board, took almost five hours to descend and, before ascending, remained on the seabed for twenty minutes.

The undertaking was important from a scientific point of view because it opened up the possibility of knowing the depths better, for example by discovering that even at very deep depths there are forms of life. In short, it wasn’t just a record.

Walsh and Piccard in Trieste

Where the bathyscaphe Trieste is now located

After the Mariana mission, the Trieste was used for other missions in the Pacific Ocean, but in 1963 it was transferred to the Atlantic to participate in the searches for the nuclear submarine USS Tresher, sunk on 10 April. In August the Trieste managed to locate some remains of the submarine at a depth of over 2,500 metres.

The story of the bathyscaphe, however, was about to end. In 1964 it was withdrawn from service and replaced with the Trieste II, which mounted the original steel sphere built in Terni, but was equipped with a new main body. The Trieste I and the sphere built by Krupp were exhibited at the Washington Naval Museum, where they can still be admired today. The Trieste II remained in service until 1980, when she was replaced by a new class of bathyscaphes.