TCS Daily

Mine the Gap

By Noah Shachtman - March 14, 2003 12:00 AM

Landmines are already some of the nastiest weapons there are. But they could soon become downright diabolical. Because the Defense Department is developing mines that can talk to one another, and move themselves around in order to cause maximum harm.

To neutralize a minefield, mine-clearers traditionally haven't had to pick up every last one of the explosives. They just had to clear a path to allow people and vehicles to pass through lethal areas safely.

A new group of mines renders this tactic obsolete. The munitions of the "Self-Healing Minefield Program" use tiny radios and acoustic sensors to stay in constant communication with each other. If some of the mines are removed, the ones that remain can "hop" hundreds of meters away, if needed, to rearrange themselves and to close the gaps.

"The minefield acts more like a fluid, and less like a static obstacle," said Dr. Tom Altschuler, who, until recently, oversaw the Self-Healing Minefield for the Defense Advanced Research Projects Agency (DARPA).

In a recent test at Sandia National Laboratories, it took less than 20 seconds for 10 self-healing prototypes to recognize that a mine had been taken away, and to shoot up like stovetop popcorn and reorder themselves. Additional testing has been done at Ft. Leonard Wood, Missouri. A test of 100 or more mines is planned for next month there, according to Altschuler.

Four years after over 130 countries pledged to abandon them, anti-personnel landmines continue to kill and injure tens of thousands around the globe every year, according to Landmine Monitor.

The mobile minefield program began with the good intention of reducing some of these casualties.

One of the main uses of anti-personnel landmines has been to keep mine-clearers away from anti-tank explosives. A dynamic, rearrangeable set of anti-tank mines would eliminate the need for anti-personnel defenses, the logic goes.

Armed with a radio transmitter, each mobile mine takes a turn broadcasting a signal to its fellow munitions, telling them to listen up. The mine then sends out an acoustic "ping," which determines that mine's relative position and distance from its mates.

The ping also determines if any mines are missing. If that's the case, the mines use pre-planned algorithms to determine the best way to heal the breach. Each mine comes with a small amount of fuel and a tiny piston. When the mine needs to move, the piston is fired into a metal "foot," which causes the mine to hop a few meters away. A mine can make as many as a hundred hops before it has to be refueled.

As currently configured, the approximately 15 pound, 10 centimeter long cylinders have magnetic triggers - ones that only a tank can set off.

"You'd have to have many, many tons of steel in close proximity to trigger (the mine). A person walking by? No effect. Even a car driving by wouldn't matter," said Dr. Mark Swinson, deputy director of the robotics center at Sandia National Laboratories.

But the new class of mines could be adjusted to affect more than just tanks. People could be targeted, as well.

Instead of being activated by metals, Altschuler suggested, the mobile mines could use triggers that only go off when a timed amount of pressure - the length of a footstep or a tire roll, say - is applied. The Italian military developed such triggers for their VS 2.2 and 1.6 mines, so they could be tossed out of helicopters without detonating.

"The reality is you can carry any payload you want (in the mobile explosives)," Altschuler continued. "It doesn't have to be an anti-tank mine."

The Army has no immediate plans to deploy the self-healing minefield, Altschuler said. But, he added, "The technology is very applicable to the Army's plans for future mine systems."

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