Alliance resources aid researchers at Northeastern University in their work to design new landmine-detection technologies.

Dirt. It seems simple. It's, well, dirt. You step on it; plant bulbs in it; wash it off your hands. But when an explosive landmine is buried in it, dirt suddenly gets more complicated.

Carey Rappaport, a professor at Northeastern University's Center for Electromagnetic Research, spends a lot of time thinking about the complications of dirt. He's leading a five-year, $5-million Army Research Office initiative to develop new technologies for detecting landmines.

An anti-tank mine (leaning against concrete block) and its smaller, more elusive cousin, a plastic anti-personnel mine (on top of block, next to rocks, tape measure, and keys).

"The key to finding a buried mine is really the dirt it's buried in," he says. "And that's a real challenge, because a handful of dirt could be anything. It could be clay. It could be sand. If it's raining, it could be mud. If it's cold, it could be frozen solid. A handful of dirt. What is that, really?"

Getting down to the nitty-gritty is essential, he says, because you can't detect a mine if your sensors can't separate it from the soil around it. Accordingly, the centerpiece of Rappaport's project is a complicated, three-dimensional computer model of dirt. Magda El-Shenawee is developing the model on NCSA's SGI Origin2000 supercomputer. She is a rough-surface computational scientist who has postdoctoral training at the University of Illinois at Urbana-Champaign and is a visiting scholar at Northeastern.

A selection of mines found in Cambodia in 1992. Courtesy of the International Committee of the Red Cross.

Because no single system can find each of the more than 600 types of mines, Rappaport plans to use a family of sensing systems—radar, sound, infrared, and electromagnetic—in conjunction with the model. Along with this family of systems comes a family of specialists: Anthony Devany in diffraction tomography, Harold Raemer in radar, and Charles DiMarzio and Steve McKnight in acoustics. All these systems operate essentially as sonar does in the sea; send out a signal, wait for that signal to bounce off an object back to a receiver, and interpret the return signal. Running different types of simulations with the dirt model at their core will show the best way to integrate and set up an overall sensing system. The simulations will also show the best way to lay out minesweeping equipment that makes up that system, such as what sort of antenna to use and whether to put the receiver above or below ground.

"But the model has to happen before anything else," says El-Shenawee. "We can't do these things in practice." It's too dangerous to experiment with the real thing.

Access Online | Posted 1-9-2001