Isn’t Twenty Thousand Leagues Under the Sea a fantasy?

100 years ago, French popular science writer Jules Verne imagined that people could sit in a boat and sneak for 20,000 miles, which was unimaginable at the time. But his fantasy has come true today. Nowadays, ships that can sneak in the sea, in addition to submarines that attack enemy ships in wars, have also developed into a large family of submersibles that are used for both research and engineering purposes.

Release a 6,000-meter underwater autonomous robot

Although sound waves can detect 10,000-meter abyss from the sea surface, the wavelength of the sound waves is still too large, and the fine structure of the seabed cannot be clearly seen. It is impossible to collect specimens from the seabed. People need to dive into the abyss to directly observe the bottom of the sea and bring things from the bottom of the sea to the surface. The huge pressure of sea water is the main obstacle for humans to dive into the deep sea.

As early as the 1960s, scientists invented the submersible. The "Trieste" manned submersible developed by the Belgian father and son Piccard successfully dived to the deepest point in the world in the Challenger Abyss in the Mariana Trench in the Western Pacific Ocean in 4 hours and 38 minutes. The depth of 10,916 meters (later accurately measured, the depth of the world's deepest trench should be 11,033 meters). Picard Jr. and American Wash maneuvered the submersible to sit steadily on the soft mud at the bottom of the Challenger Deep, and discovered that there were still jellyfish, fish and other creatures in the 10,000-meter abyss. Some submersibles developed in the early years have repeatedly accomplished extraordinary feats. They have inspected the steep ridges of the Atlantic Ocean and found that the ridges are covered with rift valleys; they have explored the latest cracks in the depths of the Red Sea and seen hot springs on the seafloor; they have also used manned submersibles to find and salvage nuclear submarines that sank in the deep sea. A hydrogen bomb lost at the bottom of the ocean. These submersibles have pressure-resistant shells. For example, the manned pressure chamber of the "Trieste" is almost spherical, with a diameter of 2 meters and a wall thickness of 127 mm, which is used to withstand water pressure of 1,000 atmospheres. Even with such a thick shell, it was still compressed by 1.5 mm when diving to a depth of 10,000 meters. The submersible is battery-powered and has self-propelled capabilities. The manned cabin has enough air, is equipped with observation windows, sonar, cameras and simple manipulators. There is also a buoyancy chamber filled with liquid lighter than water, and Some discardable ballast weights are used to control lifting. Manned submersibles are controlled by humans and can carry 2 to 4 people.

Japanese underwater robots

Manned submersibles must consider human safety and survival issues, so the cost is very high. They can be used as exploration tools and are widely used in underwater projects. It is uneconomical to use. Therefore, scientists developed a cabled unmanned submersible, or remotely operated submersible, or ROV in English. This kind of submersible does not require people to sit inside and operate it, but is controlled remotely from the ship. The power unit is on the ship, and the control signal is transmitted from the mother ship through the cable in the umbilical cord to supply electrical energy to make the submersible perform various actions. What the submersible sees and touches is converted into electrical signals and transmitted up through the umbilical cord. Because there is no human survival problem, in a submersible, except for the instruments that must be waterproof and placed in a relatively small pressure-resistant shell, most of the structures and components are exposed to seawater. The water can flow freely and the internal and external pressures are balanced. Structures and components no longer need to be designed as bulky, pressure-resistant equipment. As a result, the submersible is much lighter and cheaper than a manned submersible, and looks more like a sled than a boat. This type of submersible has been commonly used in underwater engineering.

The umbilical cord of a cabled submersible often hinders its movement, so that it cannot be too far away from the mother ship. When working underwater, you must be careful of the umbilical cord getting entangled in something. By replacing the umbilical cord with acoustic remote control and telemetry, the submersible gets rid of the cable. This cableless unmanned submersible can use acoustic signals to control its lifting, navigation, observation, sampling and operation from the mother ship.

With the further development of computer technology, submersibles have now become intelligent. The submersible can lift, navigate and work according to pre-planned procedures, can avoid occasional obstacles, and can make simple judgments based on the situation. This kind of submersible is called an autonomous submersible, also called an intelligent robot.

Now developed countries have industrialized unmanned submersibles and produced various unmanned submersibles with various acoustic detection instruments, television cameras, video cameras, and manipulators for shallow sea operations. Used in offshore engineering and coastal engineering.

Submarines on the bottom of the sea

The United States, Japan, France, and Russia have developed 6,000-meter deep-sea unmanned submersibles and manned submersibles based on the latest technology. It is equipped with a variety of detection instruments and operating equipment to investigate the seabed and to study the process of mining deep-sea manganese nodules and cobalt crusts.

Our country developed submersibles 20 years later than developed countries. my country's first manned submersible is a submarine rescue boat developed in 1986. It can carry 4 people, has a displacement of 35 tons, a maximum diving depth of 600 meters, and can dock with submarines underwater. Our country has also developed shallow-sea submersibles such as "Hairen", which can be equipped with remote-controlled focusing TV cameras and multi-functional manipulators. They have been used to check whether there are cracks in dams, and can also be used in offshore oil and gas development.

The completion of the 6,000-meter unmanned cable-free submersible supported by my country's "863 High Technology Plan" has brought my country's submersible development technology to a new level.

It can sail and work according to pre-programmed programs, automatically avoid obstacles, diagnose faults by itself, and can also be remotely controlled from the sea. It is equipped with camera equipment, oceanographic measuring instruments, acoustic navigation equipment and manipulators. It has participated in the Pacific C-C area Investigation of manganese nodules in my country.

Deep Sea Photography

In order to study the earth we live on, scientists need to understand the structure of the strata. Since the strata under the ocean are thinner than those on land, we choose to use deep-sea drilling ships to drill deep holes in the ocean to take cores to study the composition, structure, origin and history of the oceanic crust. Funded by six developed countries including the United States, the "Gloma Challenger" deep-sea drilling ship drilled 1,092 deep holes in the world's oceans from 1968 to 1983 and obtained 96,000 meters of core. This deep-sea drilling ship has a displacement of 10,000 tons. The drilling rig standing in the middle of the ship is 61 meters above the ship's waterline, and the folded drill pipe is 6.5 kilometers long. The position of the ship is fixed by acoustic methods. An acoustic beacon is dropped at the bottom of the ocean and it emits acoustic pulses. There are four receiving transducers under the ship that form an array to receive the signals from the acoustic beacon respectively. A computer is used to calculate these four signals. This signal controls the ship's position relative to the underwater acoustic beacon and remains constant. After lifting the drill pipe to take out the core sample, it is difficult to ensure that it returns to the original wellhead position when the drill pipe is lowered. In addition to using acoustic beacons for positioning, a funnel is also placed on the wellhead. As long as the drill pipe touches the funnel, it can slide into the hole at the wellhead. This device is called a return wellhead device. The data obtained by the "Glomar Challenger" confirmed the plate theory and explored the structure of the strata.