1. The Significance of Deep-Sea Exploration with Manned Submersibles
The manned submersible 'Shinkai 6500,' capable of withstanding water pressure at depths of 6,500 meters while maintaining an internal pressure of 1 atmosphere, has long supported Japan's deep-sea research. Human sensitivity, which can detect subtle changes beyond the reach of monitors and sensors, is indispensable for unexpected discoveries.
2. AUVs (Autonomous Underwater Vehicles) Utilizing AI
As a solution to the aging of manned vessels and cost barriers, the development of AUVs is advancing. Leveraging AI for automatic object detection and sampling technologies, AUVs are achieving continuous long-duration observations and high-resolution data collection, which are impossible for manned missions.
3. Hybrid Operation of Diverse Exploration Technologies
The future of deep-sea exploration hinges on balancing the desire to see directly with human eyes and the need for efficient unmanned surveys. A hybrid operation combining the strengths of manned vessels and unmanned vehicles will pave the way to unexplored seas.
At a depth of 6,500 meters, the water pressure on an area the size of a fingernail is equivalent to the weight of a small car. How do we reach a world where humans cannot survive unaided?
Japan's flagship research submersible, the "Shinkai 6500," carries people inside a rugged titanium-alloy pressure hull (73.5 mm thick, with an internal diameter of 2 m). Once the hatch is closed, "the inside stays at one atmosphere no matter how deep you go," so there is no ear pain and no need for the kind of physiological training divers require. Researchers of any age or sex can travel to the depth they need.
Continuing from the previous discussion, we spoke with Mr. Kawama, who is responsible for the maintenance of submersibles and unmanned exploration vehicles at JAMSTEC (Japan Agency for Marine-Earth Science and Technology), and Mr. Maeda, who develops unmanned exploration robots, to understand the current state of 'deep-sea access technology.'
Japan's pride, the 'Shinkai 6500' submersible, allows humans to dive inside a sturdy titanium alloy pressure-resistant shell (73.5mm thick, 2m in diameter). Once sealed, it maintains a constant 1 atmosphere regardless of depth, eliminating the need for ear pressure adjustments or training. Elderly individuals and women can reach their desired depths without issue.
Machine-based diving has a long history. In 1930, Americans William Beebe and Otis Barton explored the deep sea in a tethered bathysphere, often cited as the world's first deep-sea exploration by a crewed vessel. A year earlier, in 1929, Japanese entrepreneur Ichimatsu Nishimura had already built a small submersible. Surrounded by the sea, Japan was a world-class builder of submersibles from early on.
In the 1970s, there was a plan to build a submersible capable of diving to 6,000 meters. However, at that time, Japan only had experience with submersibles capable of diving a few hundred meters, lacking the technology and expertise to suddenly construct a 6,000-meter-class vessel.
Japan therefore first built the "Shinkai 2000" in 1981. The experience gained from developing and operating it, together with the national ambition to make science and technology a source of national strength, drove the push to 6,000 meters. Completed in 1989, the "Shinkai 6500" still carries people to the deep sea today.
Even with the advancement of robotic technology, why is there still a need for manned submersibles? Mr. Kawama cites 'human sensitivity' as the reason. High-definition 4K cameras only capture what is within the monitor's range. Similarly, scientific sensors do not react to anything outside their target. However, humans can perceive the entire space, even in the dim gray areas at the limits of light penetration. 'Sometimes, noticing an unexpected anomaly or a creature that shouldn't be there leads to discoveries when we change course,' he explains.
