At an undisclosed test site, a helicopter takes off, towing a kite-like array of massive coils.
The system, called Airborne Transient Electromagnetic (Atem) detection, works by firing a powerful pulse of electricity through a giant transmitter coil. This creates a brief, strong electromagnetic field that penetrates the ground or water.
When the pulse is turned off, the magnetic field induces tiny, decaying “eddy currents” in any conductive material it hits. These currents, in turn, create their own secondary magnetic field, which is picked up by a receiver coil.
By analysing the strength and decay rate of this secondary signal, scientists can determine not only that something is there, but what it might be and how deep it is.
The results of this groundbreaking flight test were revealed in a paper published in the Chinese journal Acta Aeronautica et Astronautica Sinica on April 25.
Led by associate professor Fu Jingcheng of Beihang University and the Chinese Academy of Sciences’ Institute of Geology and Geophysics, the study solves a formidable engineering puzzle: how to keep a complex, multi-coil airborne system perfectly stable during flight for geophysical surveys.
