Is two Wan Li under the sea a fantasy?

Many years ago, Verne, a French popular science writer, imagined that people could sneak around thousands of miles away in a small boat, which was unimaginable at that time. But his fantasy came true today. Nowadays, ships that can sneak in the sea, in addition to submarines that attack enemy ships in wartime, submersibles with both reconnaissance and engineering purposes have also developed into a large family.

Although sound waves can detect an abyss 10,000 meters from the sea surface, the wavelength of sound waves is still too large to see the fine structure of the seabed clearly, and it is even more impossible to collect samples from the seabed. People need to dive into the abyss to observe the seabed directly and bring the things on the seabed to the surface. The great pressure of seawater is the main obstacle for human beings to dive into the deep sea.

As early as the 1960s, scientists invented the submersible. The manned submersible Trieste, developed by Belgian piccard and his son, successfully dived to the deepest place in the world in Haiyuan, the challenger of Mariana Trench in the western Pacific Ocean in 4 hours and 38 minutes, and recorded the depth of 109 1033 meters (after accurate measurement, the depth of the deepest trench in the world should be 1 1033). Picard Jr. and Walsh, an American, sat firmly on the soft mud on the bottom of Challenger and found that there were jellyfish, fish and other creatures in this 10,000-meter abyss. Some submersibles developed in the early years have repeatedly made great achievements. They visited the steep ridge of the Atlantic Ocean and found that the ridge was full of cracks. I explored the latest cracks in the depths of the Red Sea and saw the hot springs at the bottom of the sea. The manned submersible also found a nuclear submarine that sank in the deep sea and salvaged the hydrogen bomb lost at the bottom of the sea. These submersibles have pressure-resistant shells. The manned pressure chamber in Trieste is almost spherical, with a diameter of 2m and a wall thickness of1.27mm, which is used to resist the water pressure of 1.000 atmospheric pressure. Even with such a thick shell, 10000 m depth is compressed 1.5 mm. Submersible vehicle has battery power supply and self-propelled ability. There is plenty of air in the manned cabin, equipped with observation window, sonar, camera and simple manipulator. There is also a buoyancy chamber, which contains liquid lighter than water, and some disposable ballast to control the lifting. Manned submersible is operated by people and can carry 2 ~ 4 people.

Manned submersible must consider the safety and survival of people, so its cost is very high and it can be used as an exploration tool, but it is not economical to use it widely in underwater engineering. Therefore, the unmanned submersible with cable, or remote control submersible, is developed, which is abbreviated as ROV in English. This submersible does not need to be operated by people sitting in it, but is remotely controlled from the ship. The power device is on board, which transmits the control signal of the mother ship through the cable in the umbilical cord, supplies electric energy, and makes the submersible do various actions. What the submersible sees and touches becomes an electrical signal, which is transmitted through the umbilical cord. Because there is no problem of human survival, most of the structures and components in the submersible are exposed to seawater. Except the necessary waterproof instruments are placed in a relatively small pressure-resistant shell, water can flow freely and the internal and external pressures are balanced, so these structures and components do not need to be designed as heavy pressure-resistant equipment. Therefore, this submersible is much lighter and cheaper than a manned submersible, and looks more like a sled than a boat. This submersible has been widely used in underwater engineering.

The umbilical cord of a submersible with cable often hinders its movement and prevents it from being too far away from the mother ship. When working underwater, you must be careful what the umbilical cord is wrapped around. Using acoustic remote control and telemetry instead of umbilical cord, the submersible got rid of the cable. This cableless unmanned submersible can control its lifting, navigation, observation, sampling and operation from the mother ship with acoustic signals.

With the further development of computer technology, the intelligence of submersible has become a reality. Submersible vehicles can lift, sail and work according to pre-planned procedures, avoid occasional obstacles and make simple judgments according to the situation. This submersible is called autonomous submersible, also called intelligent robot.

At present, developed countries have industrialized unmanned submersibles and produced various unmanned submersibles, equipped with various acoustic detection instruments, television cameras, cameras and manipulators for shallow water, which are widely used in offshore engineering and coastal engineering.

On the basis of the latest technology, the United States, Japan, France and Russia have developed 6,000m deep-sea unmanned submersibles and manned submersibles, equipped with various detection instruments and operating equipment, which are used to investigate the seabed and study the mining technology of deep-sea manganese nodules and cobalt crusts.

China lags behind developed countries for 20 years in developing submersibles. The first manned submersible in China is a submarine rescue boat developed by 1986. It can carry four people, with a displacement of 35 tons and a maximum dive depth of 600 meters, and can dock with submarines underwater. China has also developed a shallow-sea submersible, such as "Hairen", which can be equipped with a remote-controlled focused television camera and a multifunctional manipulator. They have been used to check whether there are cracks in dams, and can also be used for offshore oil and gas development.

The completion of the 6000m unmanned cableless submersible supported by China's "863 High-tech Plan" has promoted the development technology of submersible in China to a new level. It can sail and work according to pre-programmed programs, automatically avoid obstacles, diagnose faults by itself, and remotely control from the sea. It is equipped with camera equipment, ocean measuring instruments, acoustic navigation equipment and manipulator, and participated in the manganese nodule survey of China in the C-C area of the Pacific Ocean.

In order to study the earth where we live, scientists need to understand the structure of the stratum. Because the strata under the ocean are thinner than those on the land, deep-sea drilling boats are selected to drill deep holes and cores in the ocean to study the composition, structure, origin and history of the marine crust. The deep-sea drilling ship "GLOMA Challenger" was funded by six developed countries, including the United States, and drilled 1092 deep holes in the oceans of the world from 1968 to 1983, and obtained 96,000 meters of cores. This deep-sea drilling ship has a displacement of 6,543,800 tons. The derrick standing in the middle of the ship is 665.438+0 meters higher than the waterline of the ship, and the total length of the folding drill pipe is 6.5 kilometers. The position of the ship was determined by acoustic method. An acoustic beacon is dropped on the seabed to make it emit acoustic pulses. There are four receiving transducers under the ship to form an array to receive signals from acoustic beacons respectively. According to these four signals, the computer controls the position of the ship relative to the underwater acoustic beacon and keeps it unchanged. After lifting the drill pipe to take out the core sample, it is difficult to ensure that the drill pipe will return to the original wellhead position when lowering it. In addition to acoustic beacon positioning, a funnel is also placed on the wellhead, and the drill pipe can slide into the hole of the wellhead as long as it touches the funnel. This device is called reentry device. "The data obtained by the Challenger Gloma confirmed the plate theory and clarified the structure of the stratum.