When a team of Chinese engineers set out to build the deepest-diving submersible in the world, they had never laid eyes on a manned deep-sea vehicle. "We had only read some reference papers that had pictures; there was no chance for us to see a real manned submersible," says Cui Weicheng, deputy director of the China Ship Scientific Research Center and project manager for the new sub. "We were starting from the very beginning."
This past July, after 11 years of cautious labor, Cui and his team watched their submersible plunge beneath the Pacific waves, bringing three crew members to the ocean floor 5057 meters below. The Jiaolong, named after a mythical sea dragon, is not the deepest-diving manned submersible yet: That distinction still belongs to Japan's Shinkai 6500. But if the Chinese sub successfully dives to 7000 meters next year, as planned, it will take the top honor.
The Jiaolong dropped to the bottom of the northeast Pacific Ocean in a region where China has been granted mineral exploration rights by the International Seabed Authority. Unlike the venerable 47-year-old U.S. submersible Alvin, the Chinese sub is intended to earn its keep not only by conducting fundamental scientific research but also by scouting for precious metals and minerals on the seafloor.
This emphasis on an undersea vehicle's utility is a new thing in China. Several months ago, in the glossy marble headquarters of the research center, in Wuxi, Cui explained the difficult history of China's undersea-vehicle program. In the 1980s and 1990s the researchers built both remotely operated and autonomous underwater vehicles capable of reaching depths of up to 6000 meters. But, Cui notes ruefully, those vehicles were never put into operation. "In China, in the past, there was government funding to develop the technology," he says, "but there was no actual requirement for use." After these vehicles successfully completed their sea trials, they were stowed in warehouses.
For the Jiaolong, the researchers vowed, it would be different. In 2000 they submitted the proposal for a 7000-meter manned submersible to the China Ocean Mineral Resources R&D Association, a government agency. They also won government support for a new national organization modeled on the Woods Hole Oceanographic Institution, in Massachusetts. In this model, the national government provides most of the funding for a vehicle's operation, and scientists submit research proposals to gain time on the sub. Construction of the new Chinese institution, the National Deep Sea Center, began on the Shandong peninsula this year.
Despite having no experience in manned submersibles, the researchers began in 2002 to design a world-beating vehicle that could withstand pressures of 71 megapascals, or about 700 times atmospheric pressure. They took a slow and steady approach. When, after two years of sketching and planning, they had a preliminary design, they built a full-scale mock-up out of wood and steel to make sure all the planned components would actually fit together.
The first sea trials of the Jiaolong didn't take place until the summer of 2009, after years of testing the sub and its components in pressure vessels and water tanks. This first 1000-meter dive had an ominous start: The mother ship had to take shelter in a harbor while a typhoon roared by. But Cui was determined to push the trial through and insisted on heading back to sea despite the high waves. "We had a group of the engineers who were prepared to dive, but some of them had fear, and some got seasick," Cui remembers with a laugh. "In order to release their fear, I decided to dive—to show the confidence of the designer!"
If the Jiaolong proves itself at the 7000-meter dive next year, it will be ready to begin its work in earnest. But its primary task, mineral exploration, can best be accomplished if it is working in cooperation with unmanned vehicles, says Susan Humphris, who's leading an upgrade to Alvin at Woods Hole. "You could have an AUV [autonomous underwater vehicle] that surveys a large part of the ocean floor, and you could then home in on specific sites where the submersible can dive and take samples," she says. In fact, Cui has plans that include several unmanned vehicles as well as a new manned sub, both rated for 4500 meters. These vehicles can be the workhorses of the underwater fleet, Cui says, while the Jiaolong can take on more challenging missions at greater depths.
When this high-tech fleet is in operation, the science can really start. "The Chinese government's mission is to push forward the technology," says Cui. It's his mission to keep that technology out of the warehouses, and in the sea.
This article originally appeared in print as "China’s Research Sub Dives Deep".