Exploration can be a dangerous business -- even for robots. NASA has lost its share of Mars landers, and now oceanographers have lost one of their most ambitious undersea explorers.
The remotely operated vehicle, Nereus, was lost on Saturday some 6.2 miles in the ocean deep. The robotic sub was seven hours into a nine-hour dive at the deepest parts of the Kermadec Trench northeast of New Zealand when researchers lost contact with the vehicle. After failing to retrieve the sub, crew on board the research ship Thompson noticed debris from Nereus on the water's surface.
Researchers believer Nereus was destroyed during a catastrophic implosion under pressure as great as 16,000 pounds per square inch.
"Extreme exploration of this kind is never without risk, and the unfortunate loss of Nereus only underscores the difficulty of working at such immense depths and pressures," WHOI Director of Research Larry Madin said in a statement.
Although it appears to have met a violent end, Nereus (named after the mythical Greek god with a fish tail and a man's torso) had logged some valuable dives during its 6-year lifespan.
The cutting edge sub was built in 2008 by the Deep Submergence Lab at the Woods Hole Oceanographic Institution (WHOI) with primary funding from the U.S. National Science Foundation (NSF). The $8 million-dollar vehicle was equipped to dive to the deepest parts of the ocean and operate either on its own or be controlled via tether from the surface. It also traveled with a healthy power supply -- carrying packs of 2,000 rechargeable lithium-ion batteries, similar to those powering laptop computers.
On its first mission, Nereus (rhymes with "serious"), explored the deepest part of the ocean, Challenger Deep -- a nearly 7-mile-deep trench east of the Marianas Islands in the western Pacific. The trench extends deeper below the sea surface than Mount Everest reaches into the sky. Nereus not only reached these record depths, but also returned specimens of animals from the deep that had been previously unknown to science.
On other missions the sub reached the deepest known hydrothermal vents along the Cayman Rise in the Caribbean. It was due to return to the Mariana Trench in November.
"Nereus helped us explore places we've never seen before and ask questions we never thought to ask," Timothy Shank, a WHOI biologist who also helped conceive the vehicle, said in a press release. "It was a one-of-a-kind vehicle that even during its brief life, brought us amazing insights into the unexplored deep ocean"
Where Nereus left off, other undersea vehicles will have much left to explore -- an estimated 90 percent of the ocean floor remains to be charted.