Chinese engineers have completed a key stage in China's manned submersible that can descend as low as 10,000 meters, and hope to begin trials by 2020.
Chinese scientists finished the trepanning in the entrance and the cabin's observation window, the China Central Television (CCTV) reported on Monday, adding that the cabin is the key part of the submersible as it is where aquanauts stay.
The submersible can carry humans to the deepest oceans, which is about 10,000 meters below sea level, and the submersible is set for deep-sea explorations in 2020, the report said.
"Descending more than 10,000 meters enables the submersible to dive anywhere undersea, and it's significant for our marine research and data collection," Gao Shu, dean of the School of Geographic and Oceanographic Sciences at Nanjing University, told the Global Times on Monday.
Gao said that once the trials are completed, the submersible will be one of the world's most developed, and can dive the deepest.
It will help Chinese people see the "true bottom of the sea" with the naked eye, Gao said.
Trepanning the entrance and the cabin's observation window is one of the most important and challenging procedures. This one is meant to descend over 10,000 meters, and poses a great challenge to these scientists.
"The submersible will be used for 30 years, so it has to be rust-resistant. Our company can make a titanium alloy that's almost corrosion-free," Wang Dingchun, general manager of the Baoji Titanium Industry Corporation, the company building a titanium sphere, told CCTV.
"The elasticity of the metal is also important," Wang added. "It offers much better protection against the massive pressure under the sea [than steel]."
In addition, unlike the traditional way of building a sphere by welding several pieces together, only two hemispheres will be pieced together, making the sphere more solid.
The sphere's quality is the best in the country and is believed to have a leading position in the world, CCTV reported.
China became the third country after Japan and the US to build submersibles capable of reaching depths in excess of 10,000 meters, the Xinhua News Agency reported.
China made several breakthroughs in deep sea exploration as a team sailed 7,929 nautical miles to explore the trenches in the west Pacific Ocean, the Chinese Academy of Sciences (CAS) was quoted by Xinhua as saying.
The 68-day expedition made China the first to obtain 10,000-meter-deep artificial seismic profile data with a domestic ocean bottom seismograph, at the Challenger Deep in the Mariana Trench, the CAS said.