Japan building autonomous probe to explore Challenger Deep

The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is developing the compact, unmanned probe capable of reaching depths of approximately 11,000 meters, part of the abyssal zone in the Mariana Trench's Challenger Deep in the western Pacific Ocean.

The autonomous probe will collect living organisms, mud and rocks from a large area for studies on hydrothermal vents, key for understanding early life, as well as deep-sea ecosystems and ocean trenches linked to the generation of large, destructive earthquakes.

JAMSTEC, a state-backed agency based in Yokosuka, Kanagawa Prefecture, will test the probe through fiscal 2027 before putting it in full use.

The Limiting Factor, a U.S. crewed deep submergence vehicle and China's deep submersible Fendouzhe have already reached the deepest point, but their scope of exploration was limited.

In 1996, Japan's unmanned Kaiko remotely operated vehicle was the first to collect living organisms and sediment at a depth greater than 10,000 meters in the Challenger Deep, according to JAMSTEC.

Kaiko was also used to identify the wreck of the Tsushima Maru, a cargo and passenger ship sunk off Okinawa by the U.S. submarine Bowfin during World War II while carrying hundreds of schoolchildren. Kaiko was lost off Shikoku, one of Japan's main islands, in 2003.

Japan's crewed Shinkai 6500 can descend to 6,500 meters and its unmanned Urashima 8000 can go to 8,000 meters.

"We need to unlock puzzles of ecosystems and geological conditions in the deepest sea," said Yu Matsunaga, a senior official at JAMSTEC.

The probe will have to withstand enormous water pressure in the depths. It will consist of two units -- an autonomous underwater vehicle (AUV) measuring 50 centimeters in length and width and 1 meter deep, and a lander of about two meters a side that carries the AUV to the seafloor.

JAMSTEC has adopted the design because a single-unit structure would make the probe bigger, less mobile and costlier.

The probe is so designed that when the lander reaches the seafloor, the AUV will separate and vacuum up organisms and mud while moving on a predetermined route. Engineers will consider whether to add robotic arms to the vehicle.

The plan is to have the AUV stay on the seafloor for more than five hours and move a distance of around 4 kilometers. The lander, though immobile, may have a hose to gather samples from around its landing site.

In an experiment conducted in 2023, a prototype lander descended to a depth of 9,200 meters in the Japan Trench off the Boso Peninsula east of Tokyo and succeeded in sending visual data over the water by means of sound waves.

Other technologies under development include the combined use of cameras and artificial intelligence to allow the AUV to move and collect samples. If the AUV is outfitted with rechargeable batteries and allowed to navigate automatically, it will be able to expand its scope of activity as there will be no need to connect a vessel at sea with cables for communication and power supply.

JAMSTEC will begin testing the AUV and the lander as a unit in fiscal 2026 and lower the probe to 9,000 meters to collect samples in fiscal 2027. It will then begin the full use of the probe for its research activities.

As reported previosuly, China's Chang'e-7 lunar mission, expected to launch around 2026, will be equipped with a seismograph to study moonquakes and probe the lunar interior, according to Wu Fuyuan, a member of the Chinese Academy of Sciences (CAS) and a leading researcher with the Institute of Geology and Geophysics under CAS.