Bathyscaphe Trieste sphere.jpg
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A bathyscaphe ( or ) is a free-diving self-propelled deep-sea
submersible A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of ind ...
, consisting of a crew cabin similar to a bathysphere, but suspended below a float rather than from a surface cable, as in the classic bathysphere design. The float is filled with gasoline because it is readily available, buoyant, and, for all practical purposes, incompressible. The incompressibility of the gasoline means the tanks can be very lightly constructed, since the pressure inside and outside the tanks equalises, eliminating any differential. By contrast, the crew cabin must withstand a huge pressure differential and is massively built. Buoyancy at the surface can be trimmed easily by replacing gasoline with water, which is denser.
Auguste Piccard Auguste Antoine Piccard (28 January 1884 – 24 March 1962) was a Switzerland, Swiss physicist, inventor and explorer known for his record-breaking Gas balloon, hydrogen balloon flights, with which he studied the Earth's upper atmosphere. Picca ...
, inventor of the first bathyscaphe, composed the name ''bathyscaphe'' using the Ancient Greek words βαθύς ''bathys'' ("deep") and σκάφος ''skaphos'' ("vessel"/"ship").


Mode of operation

To descend, a bathyscaphe floods air tanks with sea water, but unlike a
submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
the water in the flooded tanks cannot be displaced with compressed air to ascend, because the water pressures at the depths for which the craft was designed to operate are too great. For example, the pressure at the bottom of the Challenger Deep is more than seven times that in a standard "H-type" compressed
gas cylinder A gas cylinder is a pressure vessel for storage and containment of gases at above atmospheric pressure. High-pressure gas cylinders are also called ''bottles''. Inside the cylinder the stored contents may be in a state of compressed gas, vapor ...
. Instead, ballast in the form of iron shot is released to ascend, the shot being lost to the ocean floor. The iron shot containers are in the form of one or more hoppers which are open at the bottom throughout the dive, the iron shot being held in place by an electromagnet at the neck. This is a fail-safe device as it requires no power to ascend; in fact, in the event of a power failure, shot runs out by gravity and ascent is automatic.


History of development

The first bathyscaphe was dubbed '' FNRS-2'', named after the
Fonds National de la Recherche Scientifique The National Fund for Scientific Research (NFSR) (Dutch: ''Nationaal Fonds voor Wetenschappelijk Onderzoek'' (NFWO), French: ''Fonds National de la Recherche Scientifique'' (FNRS)) was once a government institution in Belgium for supporting scient ...
, and built in Belgium from 1946 to 1948 by
Auguste Piccard Auguste Antoine Piccard (28 January 1884 – 24 March 1962) was a Switzerland, Swiss physicist, inventor and explorer known for his record-breaking Gas balloon, hydrogen balloon flights, with which he studied the Earth's upper atmosphere. Picca ...
. (''FNRS-1'' had been the balloon used for Piccard's ascent into the stratosphere in 1938). Propulsion was provided by
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
-driven electric motors. The float held of aviation gasoline. There was no access tunnel; the sphere had to be loaded and unloaded while on deck. The first journeys were detailed in the
Jacques Cousteau Jacques-Yves Cousteau, (, also , ; 11 June 191025 June 1997) was a French naval officer, oceanographer, filmmaker and author. He co-invented the first successful Aqua-Lung, open-circuit SCUBA (self-contained underwater breathing apparatus). T ...
book ''The Silent World''. As described in the book, "the vessel had serenely endured the pressure of the depths, but had been destroyed in a minor squall". '' FNRS-3'' was a new submersible, using the crew sphere from the damaged ''FNRS-2'', and a new larger float. Piccard's second bathyscaphe was actually a third vessel ''Trieste'', which was purchased by the United States Navy from Italy in 1957. It had two water ballast tanks and eleven buoyancy tanks holding of gasoline.


Accomplishments

In 1960 ''Trieste'', carrying Piccard's son Jacques Piccard and Don Walsh, reached the deepest known point on the Earth's surface, the Challenger Deep, in the Mariana Trench in the Pacific Ocean. The onboard systems indicated a depth of 37,800 ft (11,521 m) but this was later corrected to 35,813 ft (10,916 m) by taking into account variations arising from salinity and temperature. Later and more accurate measurements made in 1995 have found the Challenger Deep to be slightly shallower at 35,798 ft (10,911 m). The crew of the ''Trieste'', which was equipped with a powerful light, noted that the seafloor consisted of
diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...
aceous ooze and reported observing "some type of flatfish, resembling a sole, about 1 foot long and 6 inches across" lying on the seabed."To the bottom of the sea"
, T. A. Heppenheimer, AmericanHeritage.com
This put to rest the question of whether or not there was life at such a depth in the complete absence of light.


See also

* 1948 * 1953 * 1953 * 1961 * 1964 * 1966 * 1964 * 1987 * 2012 ''
Deepsea Challenger ''Deepsea Challenger'' (DCV 1) is a deep-diving submersible designed to reach the bottom of Challenger Deep, the deepest-known point on Earth. On 26 March 2012, Canadian film director James Cameron piloted the craft to accomplish this goal in ...
'' * * * * * *


References


External links

*
The US Navy account of the dive, with photographs
*
History of the Bathyscape Trieste

"13,000 Feet Under the Sea in the French Bathyscaphe
''Popular Mechanics'', May 1954, pp. 110–111.
Deepsea Challenger – Mariana Trench Dive (03/25/2012).
{{authority control Ship types Crewed submersibles Deep-submergence vehicles Swiss inventions