Robot sub plumbs deepest part of ocean

Falmouth, Mass – A new type of deep-sea robotic vehicle called Nereus has successfully reached the deepest part of the ocean.

The dive – to a mind-boggling 6.8 miles – was organised by a team of US engineers and scientists aboard the research vessel Kilo Moana at the Challenger Deep in the Mariana Trench in the western Pacific Ocean.

It makes Nereus the world’s deepest-diving vehicle and the first vehicle to explore the Mariana Trench in over ten years. Nereus had to withstand pressures 1,000 times that at Earth’s surface — similar to those on the surface of Venus.

The vehicle is remotely operated by pilots aboard a surface ship via a lightweight fiber-optic tether. Traditional steel-reinforced cables would snap under their own weight. Nereus can also be switched into a free-swimming, autonomous vehicle.

“With a robot like Nereus we can now explore virtually anywhere in the ocean,” said Andy Bowen, the project manager and principal developer of Nereus at the Woods Hole Oceanographic Institution (WHOI). “The trenches are virtually unexplored, and I am absolutely certain Nereus will enable new discoveries. I believe it marks the start of a new era in ocean exploration.”

WHOI engineers modified a hydraulically operated robotic manipulator arm to operate under intense pressure and make effective use of the vehicle’s limited battery power.

On its dive, Nereus spent over 10 hours on the bottom, sending live video back to the ship and collecting geological and biological samples.

“The samples collected by the vehicle include sediment from the subducting and overriding tectonic plates that meet at the trench and, for the first time, rocks from deep exposures of the Earth’s crust close to mantle depths south of the Challenger Deep,” said Fryer. “We will know the full story once the shore-based analyses are completed back at the laboratory this summer.”