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The Trieste was a Swissmarker-designed deep-diving research bathyscaphe ("deep boat") with a crew of two, which reached a record-breaking depth of about , in the deepest part of any ocean on Earth, the Challenger Deepmarker in the Mariana Trenchmarker, in January 1960.

Design

The Trieste was designed by the Swiss scientist Auguste Piccard and built in Italymarker. Her pressure sphere, composed of two sections, was built by the company Acciaierie Ternimarker, and the upper part was manufactured by the company Cantieri Riuniti dell'Adriatico, in the free city of Triestemarker on the border between Italy and Yugoslavia; hence that name was chosen for the bathyscaphe. The installation of the pressure sphere was done in the Cantiere navale di Castellammare di Stabiamarker, near Naplesmarker. The Trieste was launched on 26 August 1953 in the Mediterranean Seamarker near the Isle of Caprimarker. The design was based on previous experience with the bathyscaphe FNRS-2, also designed by the Piccards. (It was built in Belgium and operated by the French Navy). After several years of operation in the Mediterranean Sea, the Trieste was purchased by the United States Navy in 1958 for $250,000.

The Trieste consisted of a float chamber filled with gasoline for buoyancy, with a separate pressure sphere. This configuration (dubbed a bathyscaphe by the Piccards), allowed for a free dive, rather than the previous bathysphere designs in which a sphere was lowered to depth and raised from a ship by cable.

At the time of Project Nekton, the Trieste was over 15 m (50 ft) long. The majority of this was a series of floats filled with 85,000 liters (22,500 gallons) of gasoline, and water ballast tanks were included at either end of the vessel, as well as releasable iron ballast in two conical hoppers along the bottom, fore and aft of the crew sphere. The crew occupied the 2.16 m (6.5 ft) pressure sphere, attached to the underside of the float and accessed from the deck of the vessel by a vertical shaft that penetrated the float and ran down to the sphere hatch.

In the Trieste the pressure sphere provided just enough room for two people. It provided completely independent life support, with a closed-circuit rebreather system similar to that used in modern spacecraft and spacesuits: oxygen was provided from pressure cylinders, and carbon dioxide was scrubbed from breathing air by being passed through canisters of soda-lime. Power was provided by batteries.

The Trieste was later fitted with a new pressure sphere, manufactured by the Krupp Steel Works of Essen, Germanymarker, in three finely-machined sections (an equatorial ring and two caps). To withstand the high pressure of 1.25 metric tons per cm² (110 MPa) at the bottom of Challenger Deep, the sphere's walls were thick (it was overdesigned to withstand considerably more than the rated pressure). The sphere weighed 13 metric tons in air and eight metric tons in water (giving it an average specific gravity of 13/(13-8) = 2.6 times that of sea water). The float was necessary because the sphere was dense: it was not possible to design a sphere large enough to hold a person which would withstand the necessary pressures, yet also have metal walls thin enough for the sphere to be neutrally-buoyant. Gasoline (petrol) was chosen as the float fluid because it is less dense than water, yet relatively incompressible even at extreme pressure, thus retaining its buoyant properties.
General arrangement drawing, showing the main features
Observation of the sea outside the craft was conducted directly by eye, via a single highly-tapered cone-shaped block of acrylic glass (Plexiglas), the only transparent substance identified which would withstand the needed pressures, at the design hull thickness. Outside illumination for the craft was provided by quartz arc-light bulbs, which proved to be able to withstand the over-1000 atmosphere pressure without any modification.

Nine tons of magnetic iron pellets were taken on the craft as ballast, both to speed the descent and allow ascent, since the extreme water pressures would not have permitted compressed air ballast-expulsion tanks to be utilized at great depths. This additional weight was held actively in place at the throats of two hopper-like ballast silos by electromagnets, so that in case of an electrical failure the bathyscape would automatically rise to the surface.

Transported to the Naval Electronics Laboratory's facility in San Diegomarker, the Trieste was extensively modified by the Americans, and then used in a series of deep-submergence tests in the Pacific Oceanmarker during the next few years, culminating in the dive to the bottom of the Challenger Deepmarker in the Mariana Trench, the deepest part of the ocean, in January 1960.

The Mariana Trench dives

300 px
Don Walsh and Jacques Piccard inside Trieste
Trieste departed San Diego on October 5, 1959 for Guammarker aboard the freighter Santa Maria to participate in Project Nektonmarker, a series of very deep dives in the Mariana Trench.On January 23, 1960, Trieste[446] reached the ocean floor in the Challenger Deep (the deepest southern part of the Mariana Trench), carrying Jacques Piccard (son of Auguste) and Lieutenant Don Walsh, USN. This was the first time a vessel, manned or unmanned, had reached the deepest point in the Earth's oceans. The onboard systems indicated a depth of , although this was later revised to and more accurate measurements made in 1995 have found the Challenger Deep to be slightly shallower, at .

The descent to the ocean floor took 4 hours and 48 minutes at a descent rate of 0.914 m/s.. After passing 9,000 metres one of the outer Plexiglas window panes cracked, shaking the entire vessel. The two men spent barely twenty minutes at the ocean floor, eating chocolate bars to keep their strength. The temperature in the cabin was a mere 7°C (45°F) at the time. While on the bottom at maximum depth, Piccard and Walsh unexpectedly regained the ability to communicate with the surface ship, USS Wandank II (ATA-204), using a sonar/hydrophone voice communications system. At a speed of almost a mile per second (about five times the speed of sound in air), it took about seven seconds for a voice message to travel from the craft to the surface ship and another seven seconds for answers to return.

While on the bottom, Piccard and Walsh observed a number of small sole and flounder swimming away, proving that at least some vertebrate life can withstand the extremes of pressure in any of the Earth's oceans. They noted that the floor of the Challenger Deep consisted of "diatomaceous ooze". The ascent to surface took 3 hours, 15 minutes.

Since then, no manned craft has ever returned to the Challenger Deep. A Japanese robotic craft Kaiko reached the bottom of the Challenger Deep in 1995. The Nereus hybrid remotely operated vehicle (HROV) reached the bottom on May 31 2009.

Other deep dives by Trieste

In April 1963, Trieste was modified and used in the Atlantic Oceanmarker to search for the missing submarine . In August 1963, Trieste found the wreck off the coast of New Englandmarker, 8,400 feet (2.56 km) below the surface. The bathyscaphe was then retired and dismantled. The Krupp pressure sphere is now on display at the Naval Historical Center, Washington D.C.

Her original Terni pressure sphere was incorporated into the Trieste II, which also conducted some dives to the Thresher site in 1964. The pressure sphere of the Trieste II was replaced in 1966 by a new sphere designed for work at depth.

See also



Notes

  1. NGC: On the sea floor
  2. To the Depths in Trieste, University of Delaware College of Marine Studies
  3. Seven Miles Down: The Story of The Bathyscaph Trieste., Rolex Deep Sea Special, Written January 2006.


References



External links




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