Computing

Stopping Roadside Bombs

New detection technology is helping in Iraq.

The advanced technology of the U.S. military has so far met its match in Iraq in the form of improvised explosive devices (IEDs) triggered by garage-door openers, cell phones, and washing-machine timers. But this situation could be changing. New technology may make it easier to find explosives and bomb makers long before they can trigger a deadly roadside bomb.

One device the U.S. military now uses in Iraq can detect TNT vapors through bomb casings and even in land mines buried six inches underground. At checkpoints, it can smell explosive residues on the skin of bomb makers – even if they used gloves and washed their hands several times after working with TNT. Furthermore, a second generation of the detector, based on technology at least thirty times more sensitive, could be available within one to two years, says Aimee Rose, a research scientist at R&D firm Nomadics, who’s working on the new device.

According to U.S. Department of Defense releases, fifteen soldiers have been killed by IEDs since one such device seriously injured ABC news anchor Bob Woodruff and his cameraman on January 29. In fact, IEDs are the leading cause of U.S. combat deaths in Iraq, says deputy defense secretary Gordon England. The bombs have recently received more attention, as last month 600 military, industry, and academic leaders gathered in Washington, DC, to learn about and consider new solutions to the problem. IED efforts have come under the watch of a $3 billion organization led by a senior commander, retired four-star general Montgomery Meigs, former commander of NATO peace-keeping operations in Bosnia.

The TNT detector, first tested in Iraq in 2004, is now also being used in Afghanistan and in “homeland security” applications, according to Nomadics, the Stillwater, OK, company that makes the device. Instead of sensing particles of TNT, like other explosives detectors, the 2.7-pound handheld device sniffs vapors as effectively as a trained dog.

But the sensors have their limits. They cannot be mounted on a Humvee and used to detect IEDs as the vehicle drives around on patrol. Unless there is a favorable wind, the detector has to be right next to the TNT, Rose says – close enough that the IED might be detonated before a signal is read.

For that reason, the device is used primarily to find bomb makers and their explosives before a bomb is planted. “There are far fewer bomb makers than there are bombs,” says Melissa Brechwald, marketing projects manager at Nomadics. “If you get one bomb maker you’re stopping exponentially more bombs from being laid.”

Soldiers can use the devices at checkpoints, for example, to sample the air inside vehicles for traces of explosives, then either detain suspects or follow them in the hope of finding bomb-making factories, Brechwald says. The devices have also been mounted on robots for remote surveys of suspected bomb sites and weapons caches, she says.

The heart of the detector is a semiconducting polymer, originally developed by MIT chemistry professor Timothy Swager, that fluoresces when exposed to ultraviolet light. As air is pumped over this material, any TNT vapors will interfere with the fluorescence, causing it to dim. Electronics detect this change and relay the information to soldiers in the form of a bar graph and Geiger-counter-like sounds. The process takes just a few seconds, and after detecting TNT, the sensor can refresh itself in a few more seconds and be ready to test the next vehicle at a checkpoint.

The next-generation device should extend the distance at which TNT vapors can be detected and allow operation in cold temperatures, such as in the mountains of Afghanistan. It will use a polymer-based sensing element, also developed at MIT, that instead of merely glowing, produces a much more intense light in the form of a laser. When TNT vapors touch the material, it suddenly stops lasing, causing a dramatic drop-off in the amount of light. “As a consequence, you can amplify the recognition of the presence of TNT,” increasing the detector’s sensitivity, says Vladimir Bulovic, an electrical engineering professor at MIT who was involved with developing the more-sensitive device.

Rose is now adapting the device, described last April in the journal Nature, for low-power applications, by containing the polymer in micro- or nano-sized structures that lower the amount of light needed to trigger the lasing. Nomadics is also making the detector more versatile, with the goal of being able to sense more kinds of chemicals, such as the RDX used in plastic explosives. According to Rose, RDX, the second-most common explosive, after TNT, has three orders of magnitude less vapor around it than TNT, requiring the higher sensitivity for detection.

As good as bomb-detection technology may get, however, it alone will not be able to solve the IED problem. Loren Thompson, CEO of the Lexington Institute, a nonpartisan think tank in Arlington, VA, says the effectiveness of Nomadics’ technology will be limited by soldiers’ ability to control traffic in a city, which, in turn, is limited by the number of troops available. “To create a checkpoint, to continuously monitor a neighborhood for a bomb factory – we just don’t have enough personnel to do that,” he says. “You would have to rely on some sort of prior intelligence-gathering or sensor surveillance to reduce the number of prospective areas where you are going to apply the technology, otherwise it would be an insurmountable challenge.”

The U.S. military is thus pursuing efforts that can complement detection. By Thompson’s estimate, there are a somewhere around a hundred different concepts – most of them classified – for defeating IEDs. Right now, he says, the most prevalent technologies in Iraq are devices for detecting magnetic anomalies created by artillery-shell-based IEDs or jamming the signals from garage-door openers and cell phones.

The U.S. is also working to improve the way its military communicates. On the army’s Company Command website, thousands of army commanders are sharing their experiences in responding to the rapidly changing techniques of terrorist bombers.

All these combined efforts might be helping. At the end of December, Major General William Webster, commander of the Multinational Division-Baghdad, said the military is “finding nearly half of the roadside bombs, the IEDs, that the enemy is emplacing, and we’ve had a 92% increase in weapons caches found.” He said their efforts had forced insurgents to try different, less deadly tactics, such as drive-by shootings. Indeed, in January, according to the nonprofit icasualties.org, which compiles data from DOD releases, 25 soldiers died from IEDs, down from an average 40 in several previous months.

Whatever solutions work for fighting IEDs, it’s clear they will have to adapt constantly to new tactics by the bombers. The decrease in IED-related deaths in January could turn out to be a temporary downturn, if the pace of such deaths this month continues. “The basic problem you have with the IED threat,” Thompson says, “is it continuously morphs in order to circumvent solutions that we’ve developed.”

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