Robot pinpoints best locations for seafloor lab

August 14th, 2008 - 3:14 pm ICT by IANS  


Washington, Aug 14 (IANS) Sentry, an unmanned submersible, operating on its own in harsh environments, has helped scientists pinpoint and finalise the best locations for two sites of a proposed pioneering seafloor lab. Successful site selection is a vital step in developing an extensive sensor network above and below the seafloor on the Juan de Fuca Plate, according to John Delaney, University of Washington oceanographer and chief scientist for a two-week mapping expedition.

The network, which will be connected to land by underwater cables from locations near Warrenton and Pacific City, Oregon, will help unlock secrets about such things as the ocean’s ability to absorb greenhouse gases and help scientists learn how seafloor stresses cause earthquakes and tsunamis.

The network is one component of a wider project being overseen by the Consortium for Ocean Leadership as part of the National Science Foundation’s Oceans Observatories Initiative.

“The ocean community is on the threshold of a new era in which an ensemble of novel technologies will provide us with an increasingly powerful capacity for exploring and interacting with the global ocean system,” Delaney said.

“The cruise itself is an example of the coming generation of systems, where highly capable autonomous underwater vehicles (AUV) like Sentry will be integral components. Today’s AUVs are helping us develop the power and high-speed communications network we’ll need to explore powerful and potentially dangerous processes at underwater volcanoes, within powerful tsunamis or in the wake of large storms and hurricanes.”

In plans thus far, cables from two places on land will extend to five primary nodes - each about the size of a large dinner table. Like underwater extension cords, the nodes will supply power to - and communicate with - instruments, robots and smaller secondary nodes.

Choosing the right sites involved mapping and imaging in remarkable detail using sonar instruments, a towed camera and Sentry. For instance it produces maps precise to within a metre, as it glides about 250 feet above the seafloor.

Operators programme the vehicle with directions of the area to map but the vehicle is on its own when it comes to manoeuvring up and down cliffs, basins and other terrain that it encounters, all the while keeping a consistent distance from the bottom.

Sentry made six dives between July 22 and Aug 5. It was the first time the vehicle has been used during an actual oceanographic research cruise.

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

“Seeing the first maps pop up on our screen was a real thrill for us, they represent the results of hard work by all members of our team,” said Dana Yoerger, engineer, Woods Hole Oceanographic Institution, that built the robot.

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