Navy tech aids Swissair search

To help locate debris from Swissair Flight 111, which crashed off Peggy's Cove, Nova Scotia, earlier this month, the Navy has dispatched an experimental underwater mine-detection system far more capable than the Navy system used for search-and-recovery operations following the crash of TWA Flight 800 off Long Island, N.Y., in 1996.

The Mobile Underwater Detection Survey System (MUDSS), which consists of a powerful synthetic aperture sonar and an advanced electro-optic identification sensor (EIS), provided Canadian armed forces and the Canadian Coast Guard "Operation Persistence" search team "with the best resolution today in locating underwater objects," according to Cmdr. Spence Whitten, the MUDSS program manager for the Office of Naval Research, Washington, D.C.

Great Visual Clarity

Brian Coles, manager of underwater electro-optic systems at Raytheon Systems Co., said that at its highest resolution the EIS provides image clarity equal to that of black-and-white photographic film. This means that the EIS "can tell the difference between a beer can and a Coke can" on the sea bottom, Coles said.

John McCormick, a MUDSS project engineer at the Navy Coastal Systems Station, Panama City, Fla., said MUDSS has never been used operationally. He called the Swissair 111 search operation "a real success...[and] the acid test of what is an experimental system."

MUDSS works by combining sonar and EIS technologies in a single submersible, torpedo-like vehicle that feeds high-speed data to a mothership via a fiber-optic cable, Raytheon's Coles said. This package enables the Navy to use the sonar to locate objects on the ocean floor and then to use the EIS to zoom in and identify those objects at closer ranges.

The MUDSS sonar has much greater capabilities than previous sonar systems, according to McCormick, because the MUDSS sonar is totally digital, unlike the acoustic devices used in the TWA Flight 800 search-and-recovery operations.

The MUDSS sonar packs an awesome amount of computing power, McCormick said, with 10 giagabits of processing capacity provided on board the submersible by a combination of Motorola Inc. PowerPC and Digital Equipment Corp. Alpha chips mounted on VME boards.

This power, along with signal processing algorithms developed at the Coastal Systems Station, lets the sonar provide "1-inch-by-1-inch resolution...much higher than on any commercially available sonar," McCormick said.

Advanced systems such as MUDSS can even outperform human divers, which the Canadians are using extensively in Peggy's Cove, Coles said. Ray-theon recently tested the capabilities of MUDSS against a team of divers on a North Sea oil platform. MUDSS was able to "see" and identify objects at a distance of 110 feet, while divers needed to be within 35 feet.