Electronic Design

Fiber-Optic Robot Sub To Explore Deepest Terrain

Fiber optics are lighting the way to the darkest depths of the ocean. Researchers at the Woods Hole Oceanographic Institution in Falmouth, Va., are building a battery-powered robot that can explore terrain up to 36,000 feet underwater.

The hybrid remotely operated vehicle (HROV) will be able to operate in two modes. First, it will have autonomous, free-swimming capabilities for wide-area surveys. Second, it can use its tether for direction in close-up sampling and other tasks. This fiber-optic micro cable is only 1/32 of an inch, which is much thinner than other undersea tethers.

The cable was adapted from U.S. Navy applications. Because of its size and weight, the cable lets the HROV operate and maneuver at unprecedented depths without the high drag and expensive cables and winches typically used in deep-sea ROV systems. Also, the cable will enable an operator on the surface to control the HROV via two-way, real-time communications. The cable will not provide power. Once the HROV reaches the ocean's bottom, it jettisons its descent anchor assembly and continues its mission, reeling out up to 11 miles of micro cable from a canister mounted on the vehicle.

Missions can last up to 36 hours, providing ample time for collecting samples, taking photographs and video, and conducting detailed mapping and sea-floor characterization. With its hybrid nature, it can be reconfigured rather quickly for new missions, even during the same research cruise.

Researchers hope to use the HROV to explore the Mariana Trench in the Pacific Ocean, the deepest place on Earth, which descends almost seven miles under the sea. Other potential exploration sites include trenches that are active earthquake zones and under the polar icecaps. Initial trials are expected in three years.

For details, go to www.whoi.edu.

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