China Joins Deep Submergence Technology Elite

       By staff reporter ZHU HONG

Fu Wentao during the fifth dive on June 27, 2012.

        CHINA’s deep-sea manned research submersible, the Jiaolong, dived into the Mariana Trench six times between June 3 and July 16, 2012 to a maximum depth of 7,062 meters. The country now joins those in the select group, formerly comprising the U.S., Japan, France and Russia, possessing deep-sea manned submergence vessels capable of diving deeper than 3,500 meters.

State-of-the-Art Technologies

The Jiaolong successfully reached its designated dive zone at a depth of 7,000 meters, overcoming water pressure of 7,000 tons per square meter. There it completed the appointed tasks of filming the seabed and using a robotic arm to obtain marine life samples and plant the Chinese flag. The three oceanauts Ye Cong, Liu Kaizhou and Yang Bo also had a phone conversation with Shenzhou 9 astronauts in outer space while on their mission to carry out China’s first manual space docking. The Jiaolong’s successful dive signifies China’s capability to conduct deep-sea surveys in 99.8 percent of the world’s oceans.

Before establishment of the Jiaolong project in 2002, China’s manned submersibles had reached a depth of only 600 meters.

“The Jiaolong was independently and exclusively designed by Chinese engineers and technicians. We did the necessary R&D on key core technologies such as pressure-resistant structure, life support, remote underwater acoustic communication, and system control, and also carried out the final assembly, joint debugging and sea trials,” chief designer Xu Qinan said.

Xu went on to describe the three leading technologies that distinguish the Jiaolong from similar deep-sea manned submersibles of other countries. The first is state-of-the-art seabed automatic navigation, featuring a unique hovering and locating ability at a designated diving zone and the capacity to cruise at a constant height above the seabed. The Jiaolong is the first submersible equipped with such functions, according to published data. The second is the vessel’s advanced high-speed underwater acoustic communication technology. Developed by the Institute of Acoustics, Chinese Academy of Sciences, it possesses advanced micro-acoustic communication and underwater topography detection capabilities that enable the transfer of voices, images and texts from the submersible to the mother vessel in real time – a rare function among deep-sea submersibles. The third is the Jiaolong’s independently developed oil-filled silver-zinc battery that can provide over 110 kwh of electricity, that in the Russian Mir submersible its sole equivalent. The Japanese submersible battery provides 86 kwh of electricity, and those in the French and the U.S. submersibles about 50 kwh.

Mastery of Core Technologies

Around 60 percent of Jiaolong’s equipment was made in China; the remaining 40 percent was purchased from other countries. “We used many mature technologies and techniques from elsewhere in the construction of the Jiaolong, but later mastered the core technologies and skills necessary for its research and development,” Xu Qinan said.

The vessel’s seven thrusters, for example, came from an American company, but were problematic, according to Xu. A company representative came over to China but shrugged off any responsibility. “We decided to initiate the localization immediately, and in the process solved the remaining problems,” Xu said. “The noise level of the Chinese thrusters is reportedly lower than those from the U.S.”

The initial intention was also to purchase the Jiaolong’s underwater acoustic communication transducer from the U.S. The U.S. government, however, withheld the equipment after it had been sent back for repair. Undeterred, Chinese researchers rolled up their sleeves and independently developed the equipment based on that used in submersibles capable of diving 500 meters.

The manned observation capsule is also worthy of mention. Other than the access hatch cover, which China and Russia jointly designed, Chinese scientists were responsible for designing the rest of the capsule, notably the three viewports and penetration equipment. As at that time China lacked the technologies for rolling and welding the thick titanium alloy steel plate necessary to manufacture the capsule, it commissioned a Russian shipyard with the task, and tested its pressure resistance with a pressure cylinder belonging to a Russian research institute. China has since made great progress in the field, and is now capable of producing its own bulkhead for future models.

“Our R&D base was at that time relatively weak, so we encountered many difficulties, not to mention those posed by a technology-purchase blockade,” Xu said. “But the Jiaolong project has enabled us to master the international-level core technologies required for manned submersibles.”

“Many countries now show great interest in cooperating with us,” said Liu Feng, Commander-in-Chief of the deep-sea trial. “But when we started the project it was difficult even to see other countries’ submersibles, never mind gain access to their core technologies. At that time we hoped to carry out exchanges, but as we were on entirely different levels, theirs being the equivalent of a PhD and ours of a primary school student, there was no basis for communication.”

Catching Up

The Jiaolong’s 7,000-meter sea dive is by no means its ultimate goal. There are plans afoot for two scientists to dive 4,000 meters in the vessel to the South China Sea Basin seabed for purposes of deep-sea mineral prospecting, high-precision topographic surveys, suspicious object detection and capture, and deep-sea biological investigation. They will also carry out detailed investigations on polymetallic nodules in the Eastern Pacific and dive deep to the ocean’s sulfide mine sites.

“All these activities aim to better explore deep-sea resources and serve scientific research, the fruits of which will benefit ordinary people and their lives,” Liu Feng said.

The Jiaolong’s successful sea trial has prompted China’s plans to develop a series of manned submersibles. “The next task involves a 4,500-meter manned submersible, entailing R&D on such key technologies as a manned ball capsule, high-pressure seawater pump, and lithium battery and thruster. That on the manned ball capsule is expected to conclude at the end of 2013, when research into the design will commence. The whole project is expected to be finished in 2018,” Liu Feng said. “The 4,500-meter submersible is capable of meeting most domestic scientific and research demands, but at a cost of around 40 percent less than would be the case using the Jiaolong.”

The deep-sea workstation system, on which R&D is ongoing, was unveiled at the end of May 2012. In common with a small submarine, it can accommodate 12 people and remain submerged at a 1,500-meter depth for at least 12 days. The project calls for technological breakthroughs in key technologies such as deep submergence structure design, special materials, ship construction, and the sealing of underwater pressure-bearing facilities. The Jiaolong provides valuable experiences for the project.

At the same time, a deep-sea base, which a trial mother vessel and the Jiaolong are expected to occupy, is under construction that will provide protection for the Jiaolong. When the project is completed, China will become the fifth country, along with Russia, the U.S., France and Japan, to possess a deep-sea technological supporting base.

As Xu Qinan said, “China was a late starter in the deep-sea submersible field, but is working hard to catch up.”