Chemicals like TNT have a distinctive scent that can be picked up by a number of animals. Dogs are now well-established in demining, if not widespread, having already proven their value at explosives in other settings. Most often, they're used for quality assurance after a minefield has been cleared, and sometimes for preparation ahead of clearing.
"Dogs were problematic six to eight years ago," said Dennis Barlow, director of the Mine Action Information Center at James Madison University. "Now people have figured out the niche where dogs can work."
They're not inexpensive, however. Dogs can run about $24,000 apiece, or at least five times the cost of a standard metal detector.
Why turn to dogs whenare available? The canines can catch things the electronic gear misses or misreads. Clutter in the ground--nails, tin cans, old auto parts--can make it hard for metal detectors to find what they're looking for. Dogs can also negotiate rugged terrain that heavier equipment can't handle.
The campaign to locate land mines is a pressing one, with casualties numbering as many as 20,000 a year around the world from abandoned minefields.
Other, less cuddly animals could pull some of the duty, but experiments on that front haven't advanced very far. Researchers have looked into using rats, cockroaches and bees--they're a low-cost alternative and, well, they're expendable.
"No one cares if you lose a roach," Barlow said.
Some of the most compelling research focuses on bees. Bees would be useful because they can be trained very quickly to sniff out explosives. In one scenario, thousands of them would be unleashed on a potential minefield, even in thick vegetation, and theoretically would swarm over a mine or other explosive; a laser rangefinder would record the mine's location.
Bees could also be used for quality control after demining; if the swarm passes over a suspect area without stopping, that could be a good sign that the land is clear.
"To me, it has tremendous potential for a lot of areas," said Noel Mulliner, technology coordinator for the U.N. Mine Action Service.
"They appear to be able to do it. Now we have to find out how effective it is," said Noel Carruthers, technology officer at the Geneva International Centre for Humanitarian Demining.
And if the noses fall short, there may yet be mechanical alternatives such as the Nomadics Fido, a handheld device that samples air for traces of chemicals used in explosives.