Deep submergence vehicle design
Deep submergence vehicle design focuses on creating specialized vessels for exploring the depths of Earth's oceans, where conditions are extreme and largely unexplored. These vehicles are engineered to withstand immense underwater pressure and are equipped with advanced technology, including external lights and robotic manipulators, enabling them to collect deep-sea samples. Beyond marine research, they are crucial for industries such as oil exploration and telecommunications, where autonomous underwater vehicles assist in locating faulty cables and conducting resource assessments. The historical evolution of these vehicles dates back to early designs like the bathysphere, which was limited in mobility, and progressed to more advanced models like the bathyscaph and the well-known Alvin, capable of extended missions and accommodating crew members. The design considerations also include understanding the physical characteristics of the ocean, such as pressure, temperature, and light penetration, which vary significantly with depth. As technology continues to advance, deep submergence vehicles play an increasingly vital role in uncovering the mysteries of the ocean's depths, contributing to both scientific knowledge and practical applications in various sectors.
Deep submergence vehicle design
Summary: Submergence vehicles must be carefully designed to take into account undersea conditions.
Deep submergence vehicles are primarily designed to aid researchers in exploring the depths of Earth’s oceans. Much is unknown about the suboceanic environment, and exploration of these depths requires transport vehicles that can withstand tremendous pressures. Modern submergence vehicles can not only dive to great depths but can also stay submerged for hours at length, and are equipped with external lights and tele-operated robotic manipulators to gather deep sea samples for further research. Besides researching marine life, deep submergence vehicles also play vital roles in the oil exploration and the telecommunications industries where robotic submarine vehicles known as “autonomous underwater vehicles” detect faulty cables and help in oil field exploration. English mathematician William Bourne may have been the first to record a design for an underwater navigation vehicle in 1578. In addition to mathematics and mathematicians impacting deep submergence vehicles, submarines have also impacted the development of mathematics. Mathematicians examined the optimal way for airplanes to search for submarines, and the field of operations research was born.
Physical Characteristics of the Abyss
Pressure. At any given depth under the sea level, the pressure on a body can be calculated as
P = ρ × g × h
where P is pressure, ρ is the density of the seawater, g is the acceleration because of gravity, and h is the depth at which the measurement is being taken.
The atmospheric pressure at sea-level is about 100 kPa (~ 14.6 psi), the same amount of water pressure at about 10 meters (33 feet) below the surface, making the combined pressure experienced by a body at a 10 meter depth almost double of that at the surface.
Light. Most of the visible light entering the ocean is absorbed within 10 meters (33 feet) of the water’s surface. Almost no light penetrates below 150 meters (490 feet). Solid particles, waves, and debris in the water affect light penetration. The longer wavelengths of light, red, yellow, and orange, penetrate to 15, 30, and 50 meters respectively, while the shorter wavelengths—violet, blue, and green—can penetrate further. The depth of water where sunlight penetrates sufficiently for photosynthesis to take place is called the Euphotic Zone and is normally around 200 meters (655 feet) in the ocean. The zone where filtered sunlight only suffuses in the water is known as the Disphotic Zone and extends from the end of the Euphotic Zone to about a depth of 1000 meters. Below that, no sunlight ever penetrates, and this is known as the Aphotic Zone.
Temperature. There is a significant difference in the temperatures between the Euphotic and Aphotic zones. However, in the Aphotic Zone, the temperature remains almost constant, hovering around 2 to 4 degrees Celsius. The only exception occurs when deep-sea volcanoes or hydrothermal vents exist, which cause significant warming of the waters.
History
The earliest deep-sea submersibles were known as “bathyspheres” (from bathys, Greek for “deep”). They were raised in and out of the water by a cable. They were fitted with oxygen cylinders inside to provide air to the divers, and had chemicals to absorb the expelled carbon dioxide. The early bathyspheres were not maneuverable—the only degree of freedom they had enabled them to go up and down.
The notable Swiss physicist Auguste Piccard (1884–1962) was influential in making the next design iteration to the bathysphere, called the “bathyscaph.” The vessel was not suspended from a ship but instead attached to a free-floating tank filled with petroleum liquid. This tank made it buoyant (lighter than water). The bathyscaph had metal ballasts that, when released, allowed the vessel to surface. Auguste and his son Jacques designed the next generation bathyscaph, the Trieste. The Trieste set a new world record when it reached the lowest point on Earth, the Mariana Trench (35,800 feet).
Improvements in electronics and materials engineering have led to the design of Alvin, a deep-sea vessel capable of accommodating up to three people and diving for up to nine hours. Alvin sports two robotic arms that can be customized depending on the mission it is undertaking. Alvin’s most notable contribution was its role in exploring the RMS Titanic.
Bibliography
Arroyo, Sheri, and Rhea Stewart. How Deep Sea Divers Use Math. New York: Chelsea House, 2009.
Morse, Philip and George Kimball. Methods of Operations Research. Kormendi Press, 2008.
Mosher, D. C., Craig Shipp, Lorena Moscardelli, Jason Chaytor, Chris Baxtor, Homa Lee, and Roger Urgeles. Submarine Mass Movements and Their Consequences. New York: Springer, 2009.