Robot vehicle surveys deep sea off Pacific Northwest

Washington, August 14 : A newly developed robotic vehicle has successfully completed its first scientific mission by surveying deep sea off the Pacific Northwest.

Developed by a team of scientists and engineers from the Woods Hole Oceanographic Institution (WHOI) and the University of Washington (UW), the robot, called 'Sentry', is capable of diving as deep as 5,000 meters (3.1 miles) into the ocean.

The vehicle surveyed and helped pinpoint several proposed deep-water sites for seafloor instruments that will be deployed in the National Science Foundation (NSF)'s planned Ocean Observatories Initiative (OOI).

Sentry is a state-of-the-art, free-swimming underwater robot that can operate independently, without tethers or other connections to a research ship.

The autonomous underwater vehicle, or AUV, is pre-programmed with guidance for deep-water surveying, but it can also make its own decisions about navigation on the terrain of the seafloor.

According to Julie Morris, director of NSF's Division of Ocean Sciences, "In the near future, Sentry will conduct high-resolution oceanographic surveys that would be otherwise impossible."

Working in tandem with sonar instruments on the UW-operated research vessel Thomas G. Thompson and with photo-mapping by WHOI's Tow Cam seafloor imaging system, Sentry gathered the most precise maps to date of seafloor features known as Hydrate Ridge and Axial Volcano off the coast of Oregon and Washington.

The one-of-a-kind, WHOI-built AUV- which was largely funded by NSF- made six dives during the July 22 to August 5 expedition.

Sentry surveyed 212 linear kilometers of seafloor, or about 53 square kilometers, as it traced parallel lines like a lawn-mower making a pattern across a yard.

"Sentry had a very successful introduction," said Dana Yoerger, the lead WHOI engineer for the vehicle. "We had tested the AUV as best we could before we got out here, but the steep terrain of the deep sea is quite a different matter," she added.

The AUV can collect the data needed to make seafloor maps at a resolution of less than one meter.

On this first cruise, Sentry collected as many as 60 million individual soundings of seafloor depth in a single dive.

Powered by more than 1,000 lithium-ion batteries-similar to those used in laptop computers, though adapted for extreme pressures, Sentry dove for as long as 18 hours and 58 kilometers, with the potential for longer trips in the future.

Sentry is designed to swim like a fish or fly like a helicopter through the water.

The sleek hydrodynamic design allows the vehicle to descend quickly from the sea surface to the depths (about 3,500 meters per hour). The novel shape also gives the vehicle tremendous stability and balance while cruising through bottom currents.

According to Rod Catanach, a WHOI engineer, "Sentry is a true robot, functioning on its own in the deep water."

ANI