R.I.P. Nereus

by Sara E. Pratt
Tuesday, August 19, 2014

Nereus, the United States' only full-ocean-depth submersible, was lost at sea on May 10, 2014. The unmanned and remotely operated vehicle was capable of reaching the hadal zone, the ocean region 6 to 11 kilometers deep, and was designed, built and operated by Woods Hole Oceanographic Institution (WHOI) in Massachusetts. Nereus was at a depth of 9,990 meters in the Kermadec Trench off New Zealand, the fifth-deepest ocean trench in the world, when it lost contact with researchers aboard the R/V Thomas G. Thompson. Debris later surfaced, which was recovered and determined to be the remains of the vessel. The debris indicated a catastrophic implosion, likely of one or more of the vehicle’s ceramic buoyancy spheres.

The loss occurred on day 30 of a 40-day cruise that was part of the Hadal Ecosystems Studies program (HADES) to study the hadal zone, composed mainly of 21 deep-ocean trenches, which combined cover an area about the size of Australia. The loss of the $8 million vehicle, in operation since 2009, means that researchers can no longer systematically survey more than a third of the ocean. WHOI is currently designing and building another hadal submersible in collaboration with the Schmidt Ocean Institute, a private ocean research foundation founded in 2009 by Google executive chairman Eric Schmidt.

“Nereus helped us explore places we’ve never seen before and ask questions we never thought to ask,” said WHOI marine biologist and HADES chief scientist Timothy Shank, who also helped design the vehicle, in a statement. “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.”

Read a first-hand account of the day Nereus was lost written by WHOI science writer Ken Kostel aboard the R/V Thomspon at: http://web.whoi.edu/hades/a-sad-day/.

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