Being a sub-hunter has gotten tough, lately. The new diesel subs that Iran and China are buying up are tiny, quiet, and can swim through the crannies that hug the coasts. That makes 'em really hard to find. And it's a major reason why the U.S. Navy is switching from passive sonars to Slayer-loud, active sonars that makes whales slam dance onto dry land.

Australian scientists may have found a better way to find these quiet subs, The Engineer reports -- one that doesn't drive whales psycho.

The Australian development, called MAGSAFE, uses the detection of changing magnetic fields to identify and monitor a moving submarine. The method, which is unique in that it captures 12 magnetic field-related data values per reading as opposed to the single number measured by a conventional magnetic anomaly detector (MAD) magnetometer, arises from research into new minerals exploration technologies that detect magnetic fields...

The technology is basically a 'tensor gradiometer', which is a device that can measure minute changes in magnetic field gradients. It uses three independent rotating sensors, which use high-temperature superconducting quantum interference devices (SQUIDs) to monitor the magnetic field gradient.

In theory, the system means that pilots whose aircraft are fitted with MAGSAFE detectors will be able to measure the range, depth and bearing of a submarine, how fast it is going and if it is diving - all from one flyby. (Big ups: RC)