The science ministry is giving priority to the development of unmanned submersible to replace the Shinkai 6500, the venerable manned research submersible responsible for Japan’s deep-sea exploration for more than 30 years.

The design life of the Shinkai 6500 is nearing an end, and the technology to build a successor manned submersible has been lost.

Japan now hopes to catch up in the intensifying competition among countries to develop a highly sophisticated probe for research and discovery of undersea resources.

The Shinkai 6500 is owned by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). Completed in 1990, it is Japan’s only manned research submersible and has made more than 1,700 dives.

If it continues to be used as is, its spherical cockpit, known as the “pressure-resistant shell,” will reach the end of its design life in the 2040s.

The pressure-resistant shell, made of titanium alloy, is a nearly perfect sphere with an inner diameter of 2 meters. But the technology for creating it has not been passed down, officials said.

The emergency surfacing equipment and other features are also aging, but the manufacture of them has been discontinued.

The ministry’s expert panel noted that it would be “extremely difficult” to build a manned research submersible as good as the Shinkai 6500.

JAMSTEC intends to use the Shinkai 6500 for its lifetime and then shift the focus to unmanned submersible equipped with artificial intelligence.

On Aug. 1, the ministry’s subcommittee on ocean development, which is the parent committee of the expert panel, decided to prioritize development of an unmanned probe capable of observations and taking samples at depths of 6,500 meters or more.

Instead of viewing the deep sea through the window of a manned submersible, JAMSTEC plans to develop a system that allows observation through the unmanned submersible’s cameras using virtual reality technology.

Deep-sea exploration is positioned not only for academic research on ecosystems and seafloor topography but also to contribute to economic security through the exploration of energy and mineral resources.

The University of Tokyo and the Nippon Foundation announced in June that they had identified an area on the seafloor near Japan’s easternmost island of Minami-Torishima where minerals containing rare metals, including cobalt and nickel, are concentrated.

They announced a plan for large-scale extraction starting in 2025.

The existence of these minerals was confirmed in a survey conducted by the Shinkai 6500 in 2016.

“If we can develop Japan’s EEZ (Exclusive Economic Zone), we may be able to industrialize it by using domestically produced resources,” said Yasuhiro Kato, a professor of earth resources at the University of Tokyo.

Japan is a “deep-sea power.” It has the world’s largest volume of water below 5,000 meters in its territorial waters and EEZ.

Hiroshi Kitazato, a visiting professor of earth and life sciences at Tokyo University of Marine Science and Technology, said: “Japan is a treasure house of deep-sea research. It would be a shame to lose access to the deep-sea research sites that are so close by.”

The development of deeper-diving and more sophisticated probes is progressing overseas among countries that want to lead in deep-sea science and technology.

China has a 10,000-meter class manned submersible, and the United States also has a civilian research submersible of a 10,000-meter class.

India is building a 6,000-meter-class manned submersible, expected to be completed in 2026.

Unmanned submersibles cater to business needs, such as undersea resource development and construction of offshore wind power generation facilities.

Unmanned submersibles of 6,000-meter or higher class have been introduced in Europe, South Korea and Australia.

Many countries are promoting domestic production of unmanned submersibles from the perspective of economic security.

Japan once boasted the world’s top diving capability. But now it is falling behind.

In particular, Europe and the United States are ahead in the development of autonomous underwater vehicles (AUVs).

Most of Japan’s AUVs are foreign-made. For this reason, the Japanese government last year devised a strategy to domestically produce AUVs by 2030.

A ministry official said the policy of prioritizing development of unmanned submersible “does not mean we are backing away from the development of manned submersible,” but it is rather an indication of “what needs to be done immediately to ensure that deep-sea research does not cease.”

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APOLOGY

The sixth paragraph of the article on the Shinkai 6500 has been deleted.

The original paragraph referred to the Shinkai 6500 and read: “The current state is not good,” said Kenichiro Tani, a chief researcher at the National Museum of Nature and Science who is a member of the ministry’s expert panel that discusses future deep-sea research policy. “Early countermeasures against aging are necessary, but the sense of crisis felt in the field is that even if life-prolonging treatment is given, will it still be usable?”

The quoted remarks by Tani were actually about the Yokosuka, a support ship for the Shinkai 6500.

The Asahi Shimbun reporter, who attended the expert panel’s meeting, misunderstood the subject of Tani’s remarks and used the quotes in the article without confirmation. We apologize for the error.