Beach Cleanup

beach_485.jpg

Since 2001, more than 13,000 American soldiers have been killed or maimed by landmines or improvised explosive devices. Civilians included, landmines kill or injure an estimated 20,000 people around the world every year. To blaze safer trails, the U.S. Office of Naval Research is developing a system that uses thousands of chemical- and explosive-packed darts to snuff out landmines. "It's one of the most successful systems we've tested so far," says project leader Brian Almquist.

Mines are often equipped with a touch or tilt trigger, making them extremely difficult to safely defuse by hand or by robot, and the current method for clearing mines from a safe distance-dropping a large blast warhead on the field-works only on ones laid above-ground. The new system circumvents these problems by employing a cylindrical bombshell packed with 6,500 darts.

When dropped from the safety of an airplane, the GPS-guided bomb ejects the darts and spreads them out in a 60-foot circular pattern. Each dart is designed to burrow several feet into sand or water, pierce the exterior of a mine, and defuse or detonate it. For safety reasons, any explosive darts that don't hit mines self-sterilize.

Almquist and his team are still modifying the darts, and the project needs approval from the Naval Sea Systems Command Acquisition Program to move out of the lab, but a fieldable system could be ready by 2015.

HOW IT WORKS

1. A plane drops a bomb packed with darts. Once it reaches 1,000 feet above its target, the bomb ejects a seven-foot-long tubular canister.

2. A corkscrew pattern carved into the bomb's interior spins the canister as it slides out, like a bullet leaving a gun. The rotation and small explosives jettison the canister's panels and expose 6,500 darts stacked several rows deep. The mass of darts is also spinning, which uniformly disperses them.

3. Each seven-inch dart slams into the ground at 1,200 feet per second. Its blunt nose helps it carve a channel in water or sand, a process called cavitation. This reduces friction on the body of the dart and allows it to pass through two feet of sand and more than seven feet of water.

4. Darts inject the mines with one of three substances: a chemical that safely burns the TNT, a reactive powder that breaks apart the mine by increasing internal pressure, or a small explosive that detonates the mine on impact.