Detecting bombs with sensor

Using technology for finding underground mineral deposits, the CSIRO has developed a sensor that will detect bombs on the sea floor. Although untested in water, it has been proved in a stationary laboratory environment.

The development was part of a project with the US Strategic Environment Research and Development Program (SERDP) and the American-based research organisation Sky Research.

In operation, the sensor provides data on the location, characteristics and magnetic qualities of the target and distinguishes between, say, gold and an explosive.

Says CSIRO electrical engineer Dr Keith Leslie: “Our highly sensitive sensor - the high-temperature superconducting tensor gradiometer - delivers significantly more information about the target’s magnetic field than conventional sensors used for this type of detection.”

More than 2.4 m hectares of coastal waters are contaminated by undetonated explosives, according to SERDP.  Under water they corrode, making them even more dangerous.

Leslie pointed out that trying to detect objects in the sea is difficult because of electrical currents generated by waves which then affect underwater magnetic fields.

“In mineral exploration, new surface deposits are being exhausted leading us to search for minerals deeper underground where targets are more difficult to detect with traditional surface and airborne measurements,” he said.

The CSIRO sensor can provide geological information that discriminates between prospective and non-prospective areas or targets and so avoids unnecessary drilling, minimising the risk of overlooking mineral deposits.

For detecting small targets such as explosives, the sensor has a big advantage where only one or two measurements may be near the target.

“In mineral exploration, a string of measurements of the gradients of the magnetic field down a drill can determine the direction to a target,” he said.

It is expected that eventually the technology may be used at abandoned mine sites where originally drilling programs were based on insufficient or inaccurate information. It also has the potential to help clear landmines.