Run silent, run invisible

Date:1 May 2011 Tags:

A submarine’s biggest asset is its ability to remain elusive. but as potential foes acquire better detection equipment, the us navy must constantly develop new ways to hide subs. – AH

1. Lurking in the shadows

Squid, octopus and cuttlefish have light-sensing proteins called opsins that adjust the animals’ skin patterns to match the light and colour around them. A joint team of university researchers, working with the Marine Biological Laboratory in Woods Hole, Massachusetts, and the Office of Naval Research, is developing nanomaterials that, like opsins, can sense light and rapidly change colour to defeat detection by satellites, aircraft or on-deck observers.

2. Sonar stealth

Engineers at the University of Illinois have built an acoustic cloaking device that guides sound waves around an object, making it invisible to sonar. The disc prototype is grooved with concentric rings that capture incoming sound waves and send them into a spiral instead of bouncing back toward their source, which means there’s no sonar echo. Another potential use: creating filters that reduce interference during medical ultrasound imaging.

3. Masking invisible waves

The magnetism of a sub’s hull increases as it moves through water, leaving a signal that airborne sensors, mines and torpedoes can use to target it. Every year, the US Navy erases these magnetic signatures by running high electrical currents through copper cables strung across subs’ hulls. Now, Navy engineers are building a “drive-in” facility in Hawaii with a permanent frame and wiring that can demagnetise the hulls quickly. The facility opens in 2013.

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