Advances in airborne geophysical systems for ordnance mapping and detection

Over the past 10 years, several advances have been made in helicopter geophysical systems for mapping and detection of unexploded ordnance (UXO). Earlier total-field magnetometer systems for this application invoked a novel boom-mounted sensor design, which en-abled safe operation at altitudes of a few meters above ground level and permitted detection of individual small ferrous objects. The first such system, the Aerodat HM-3, had three cesium vapor magnetometers at 6-m spacing, mounted at the tips of one forward and two lateral booms (Gamey and Mahler, 1999). Subsequent improvements incorporated as many as eight magnetometers at 1.7-m spacing (Doll et al., 2003), as in the ORAGS-Hammerhead and ORAGS-Arrowhead systems. Since that time, improved magnetometer systems have been developed, and a production time-domain electromagnetic system has been introduced.