The Xiangyanghong 09, an oceanographic ship carrying China`s manned deep-sea submersible, the Jiaolong, leaves the eastern port city of Jiangyin for the Mariana Trench on a mission to attempt the world`s deepest manned submersible dive. The Jiaolong`s three crew aim to dive 7,000 meters below the surface of the Pacific.

>An oceanographic ship carrying China`s manned deep-sea submersible, the Jiaolong, left the eastern port city of Jiangyin yesterday for the Mariana Trench to attempt the world`s deepest manned submersible dive.

The submersible, named after a mythical sea dragon, will dive 7,000 meters below the surface of the Pacific Ocean between mid-June and early July.

Oceanauts Ye Cong, Fu Wentao and Tang Jialing will pilot the Jiaolong and will be supported by nearly 100 scientists who will test the submersible`s functionality, conduct research and take seabed samples.

The Haiyang-6, a Chinese research vessel, carried out surveys in the Mariana Trench earlier this year to find the best environment for the Jiaolong, a manned submersible designed to reach depths of 7,000 meters.

It completed 17 dives in the South China Sea between May and July 2010, with the deepest reaching 3,759 meters. This dive made China the fifth country, following the United States, France, Russia and Japan, to send a manned submersible to a depth of more than 3,500 meters below sea level.

The submersible succeeded in diving 5,188 meters below sea level in the Pacific Ocean last summer, enabling China to conduct surveys in 70 percent of the world`s seabed areas.

"The challenge for this dive is that the submersible must bear extremely high pressure, much greater than the pressure it faced at a depth of 5,000 meters," said Liu Xincheng, an official with the State Oceanic Administration.

Xu Qinan, chief designer of the Jiaolong, said scientists had improved the submersible`s hydraulic pressure system to endure the high pressure and low temperatures found at 7,000 meters.

GPS equipment has been installed on the Jiaolong and its accompanying ship, the Xiangyanghong 09, has received upgrades that will allow scientists aboard to detect the Jiaolong`s location.

"The Jiaolong`s expedition is aimed at benefiting all of mankind," said head operator Ye. "The deep sea has amazing resources waiting to be discovered, such as hydrothermal sulfide and manganese nodules." 

Tang said that he and the other oceanauts had undergone extensive physical training and simulations in preparation for the dive.

China initiated the Jiaolong project in 2002. 

The vessel is expected to return to China in the middle of next month.

The United States, Russia, Japan and France currently lead the world in the development of deep sea exploration technology.