News Item

Woods Hole robot lost at sea

March 10, 2010 — via Cape Cod Times

By Aaron Gouveia

ABE was lost on March 5 during an expedition off the coast of Chile, WHOI officials said. Researchers had just dispatched ABE for its second dive to the Chile Triple Junction, which is the only place on Earth where a mid-ocean ridge is being pushed underneath a continent in a deep ocean trench, a geologic process known as subduction.

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WOODS HOLE — ABE has been lost at sea off the coast of Chile, claimed by the same waters it once spent countless hours exploring.

The Autonomous Benthic Explorer, nicknamed ABE, is a 15-year-old, unmanned underwater robotic vehicle used to map the sea floor, collect samples and allow scientists to better analyze underwater discoveries, according to officials at the Woods Hole Oceanographic Institution. The Woods Hole scientific center designed and operated the submersible.

Built in 1995 using $1 million from the National Science Foundation, ABE was the first untethered vehicle in WHOI's fleet that allowed scientists to explore up to three miles beneath the surface in harsh, rugged areas not accessible by manned vehicles.

ABE was lost on March 5 during an expedition off the coast of Chile, WHOI officials said. Researchers had just dispatched ABE for its second dive to the Chile Triple Junction, which is the only place on Earth where a mid-ocean ridge is being pushed underneath a continent in a deep ocean trench, a geologic process known as subduction.

Aside from making the area prone to earthquakes such as the 8.8 magnitude one that hit Chile last month, subduction also creates hydrothermal vents, which are essentially underwater volcanoes that spew super-heated water mixed with chemicals such as methane, iron and hydrogen sulfide. In recent years, scientists have discovered several new kinds of animal and plant life at hydrothermal vents.

ABE detected hydrothermal vents on its first dive. But when it returned to the almost two-mile deep area the following day, contact between the robot and the surface vessel abruptly ceased.

Researchers believe one of ABE's glass spheres may have imploded. The pressure at ABE's depth would have been more than two tons per square inch, destroying everything onboard the 1,200-pound submersible and ruining any chances of ABE being able to float back to the surface.

The accident had nothing to do with the earthquake or any aftershocks, WHOI officials said.

"ABE was a vehicle that we'll always have fond memories of," said Christopher German, WHOI's national deep-submergence facility chief scientist who is currently off the coast of Chile. "It was a world-beater in its day."

WHOI officials said ABE was on its 222nd dive when it was lost.

ABE was the first autonomous robotic vehicle to make detailed maps of mid-ocean ridge, which is the 40,000-mile underwater volcanic mountain chain at the boundaries of Earth's tectonic plates. ABE was also the first vehicle to locate deep-sea hydrothermal vents.

ABE traveled in back and forth motions, often referred to as "mowing the lawn," making highly detailed maps using multibeam sonar, Doppler navigation and an anchoring system. It was pre-programmed on a designated course, but also had the capability to avoid collisions on its own.

In 2006, ABE was honored by Wired magazine as one of the "50 Best Robots Ever," joining Mars rovers and unmanned aerial drones.

Brian Midson, technical operations specialist at the National Science Foundation, said ABE was "pretty incredible," and he said the mood among those who created, operated and maintained it has been somber. "These guys nurtured this system and worked with every component for 15 years," he said. "There's a lot of sentimentalism in oceanography."

ABE already has a replacement that is fully operational.

The Sentry is a new and improved model, and the only reason it was not used on the Chile trip is that it is currently surveying another part of the ocean.

ABE was actually retired, but was called back into service for one last trip. But Midson said ABE was in good working order and had been cleared for use prior to the expedition.

Like Midson, German is disappointed to lose the undersea vehicle, and he said on his expedition blog that ABE "will always have a special place in my heart."

However, he said this is not the last people have seen of the beloved submersible.

At a subduction rate of 10 centimeters a year, German estimates that ABE will be swallowed up beneath the continental margin around 16,000 years from now. But as the subducting plate sinks, anything buried within the sediment of the upper crust will melt and rise up beneath the Andes to erupt as volcanic lava.

"So in the spirit of our engineers, as well as in the world's most impressive geological recycling center, we can be quite clear: ABE will rise again," German said.

ABE AT A GLANCE

Built: 1995
Cost: $1 million
Dimensions: Length, 10 feet; width, 6.5 feet; height, 8 feet
Weight: 1,200 pounds
Operating Range: 14-20 hours
Operating Speed: 0 to 1.5 mph