China is getting a step closer to exploring the bottom of the Mariana Trench, the largest crack in the Earth's surface, after the welding of the spherical shell of the submersible's capsule was completed on Saturday.

According to Lei Jiafeng, research fellow of the Institute of Metal Research affiliated with the Chinese Academy of Sciences, China is the first country to build such a large deep-sea manned submersible with titanium alloy materials able to last for over 30 years.

Upon completion, the submersible, capable of diving to depths of over 10,000 meters, will become one of the most advanced deep sea vehicles with the biggest diving depth in the world.

As one of the core components of the submersible, the spherical capsule also serves as a restaurant, a living room, as well as an operation compartment for the pilots.

The technology – joining metals using vacuum electron beam welding and applied on the capsule shell, leaves very narrow space for the welded joints and can weld into a relatively deep position.

By digitally analyzing the movement of the beam, the task was done with great accuracy.

"We used to do manual welding. Now it is welded in a vacuumed environment and it is highly demanding in the precision control of the electron beam. It is no longer controlled by a person. With the parameters fixed, the computer will do the rest stably and accurately," said Ye Cong, chief designer of the manned submersible.

The pressure the vessel will be subjected to at 10,000 meters below surface is similar to that of a car on a fingernail. (CGTN)