Research sub lost in ocean trench

One of the world’s most capable deep-sea research submarines has been lost in the Pacific Ocean.

The robotic vehicle Nereus went missing while exploring one of the ocean’s deepest spots: the Kermadec Trench, which lies north-east of New Zealand.

Surface debris was found, suggesting the vessel suffered a catastrophic implosion as a result of the immense pressures where it was operating some 10 kilometres down.

Nereus was a flagship ocean explorer for the US science community.

“Nereus helped us explore places we’ve never seen before and asks questions we never thought to ask,” said Timothy Shank, from the Woods Hole Oceanographic Institution (WHOI), which managed the sub’s activities.

“It was a one-of-a-kind vehicle that even during its brief life brought us amazing insights into the unexplored deep ocean, addressing some of the most fundamental scientific problems of our time about life on Earth.”

The US$8 million robot was built in 2008 and could operate in an autonomous mode or remotely controlled via a tether to a support ship to explore the Earth’s deepest oceanic trenches.

It used a lot of innovative technologies that allowed it to do things and go places that were off-limits to other research submersibles.

These technologies included rechargeable lithium-ion batteries, similar to those used in laptop computers, for extended power, and single-hair’s-width fibre-optic cables – borrowed from torpedoes – for control and telemetry.

Leading British oceanographer Jonathan Copley, from the University of Southampton, said the loss of an underwater vehicle was an ever-present risk.

“To obtain some kinds of knowledge – particularly when physical samples are required for analysis – there is no alternative to sending equipment into the deep ocean, because the ocean’s watery veil masks its depths from many forms of ‘remote sensing’”, he wrote on a University of Southampton blog this weekend.

“And although we have learned a lot from a century or so of largely ‘blind sampling’ by equipment such as trawls and seabed corers –which are still fine for answering some questions in some areas – we now often require more detailed sampling and surveying, using deep-sea vehicles, to answer further questions.”

The unmanned vehicle was on day 30 of a 40-day mission to explore the Kermadec Trench northeast of New Zealand. It dove to depths ranging from 6000 to 11,000 metres. When it imploded, the vehicle was under pressure as great at 16,000 pounds per square inch.

Nereus wasn’t the first great loss to the institution. In March 2010, ABE, a predecessor to Nereus, was lost off the coast of Chile. No trace of the submersible was ever found.

The institution is already in the process of building the next generation of Nereus, a group of submersibles that will explore the ocean at different depths.

Two of the submersibles, called Nereids, have already been built and another is on its way to completion.

One of them one will have the 11,000 metre depth that Nereus was designed for,” WHOI Director of Research Laurence Madin said.