A bathyscaphe () is a

free-diving Freediving, free-diving, free diving, breath-hold diving, or skin diving, is a mode of underwater diving that relies on apnea, breath-holding until resurfacing rather than the use of breathing apparatus such as scuba set, scuba gear. Besides the ...

, self-propelled

deep-sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low tempe ...

submersible A submersible is an underwater vehicle which needs to be transported and supported by a larger ship, watercraft or dock, platform. This distinguishes submersibles from submarines, which are self-supporting and capable of prolonged independent ope ...

, consisting of a crew cabin similar to a ''

Bathysphere The ''Bathysphere'' () was a unique spherical deep sea, deep-sea submersible which was unpowered and lowered into the ocean on a cable, and was used to conduct a series of dives off the coast of Bermuda from 1930 to 1934. The ''Bathysphere'' wa ...

'', 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 equalizes, eliminating any differential. By contrast, the crew cabin must withstand a huge pressure differential and is massively built.

Buoyancy Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...

at the surface can be trimmed easily by replacing gasoline in the tanks with water, because water has a greater density.

Auguste Piccard Auguste Antoine Piccard (28 January 1884 – 24 March 1962) was a Swiss physicist, inventor and explorer known for his record-breaking hydrogen balloon flights, with which he studied the Earth's upper atmosphere and became the first person to ...

, inventor of the first bathyscaphe, coined the name ''bathyscaphe'' using the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

words (), meaning 'deep', and (), meaning 'vessel, ship'.

Mode of operation

To descend, a bathyscaphe floods air tanks with sea water, but unlike a

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

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 The Challenger Deep is the List of submarine topographical features#List of oceanic trenches, deepest known point of the seabed of Earth, located in the western Pacific Ocean at the southern end of the Mariana Trench, in the ocean territory o ...

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. Gas storage cylinders may also be called ''bottles''. Inside the cylinder the stored contents may be in a state of compressed gas, vapor ov ...

. Instead, ballast in the form of

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

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 In engineering, a fail-safe is a design feature or practice that, in the event of a failure causes, failure of the design feature, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. ...

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 The ''FNRS-2'' was the first bathyscaphe. It was created by Auguste Piccard. Work started in 1937 but was interrupted by World War II. The deep-diving submarine was finished in 1948. The bathyscaphe was named after the Belgian Fonds Nationa ...

'', named after the Fonds National de la Recherche Scientifique, and built in

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

from 1946 to 1948 by

. (''FNRS-1'' had been the balloon used for Piccard's ascent into the stratosphere in 1938). Propulsion was provided by battery-driven

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

s. 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 open-circuit self-contained underwater breathing apparatus (SCUBA), called the ...

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 The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

from

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

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 Jacques Piccard (28 July 19221 November 2008) was a Swiss oceanographer and engineer, known for having developed submarines for studying ocean currents. In the Challenger Deep, he and Lieutenant Don Walsh of the United States Navy were the fi ...

and

Don Walsh Don Walsh (November 2, 1931 – November 12, 2023) was an American oceanographer, U.S. Navy officer and marine policy specialist. While aboard the bathyscaphe ''Trieste'', he and Jacques Piccard made a record maximum descent in the Challeng ...

, reached the deepest known point on the Earth's surface, the

, in the

Mariana Trench The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deep sea, deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maxi ...

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'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

aceous ooze and reported observing "some type of flatfish, resembling a sole, about 1 foot long and 6 inches across" (30 by 15 cm) 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.

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

Mode of operation

History of development

Accomplishments

See also

References

External links