Experiments carried out by the United States and former Soviet Union achieved maximum detection depths of less than 100 meters, according to openly available information. The detection depth has been extended in recent years by the US in research funded by Nasa and the Defence Advanced Research Projects Agency (DARPA). A device developed by DARPA, for example, was mounted on a spy plane and achieved reliable results at a depth of 200 meters, detecting targets as small as sea mines.
Light dims 1,000 times faster in water than in the air, and the sun can penetrate no more than 200 meters below the ocean surface, a powerful artificial laser beam can be 1 billion times brighter than the sun. Naval researchers have tried for more than half a century to develop a laser spotlight for hunting submarines using technology known as light detection and ranging (lidar).
The satellite is designed to generate high-power laser beam pulses in different colors, or frequencies, that allow sensitive receivers to pick up more information from various depths. Those laser beams can scan an area as wide as 100km, or concentrate on one spot just 1km wide.
It will be used in conjunction with a microwave radar, also mounted on the satellite, to better identify targets.
Although the radar cannot penetrate water, it can measure the surface movement with extremely high accuracy – so when a moving submarine creates small disturbances on the surface, for example, the radar will tell the satellite where to throw the laser beam.
The team is working to combine every available sensing method to achieve the maximum possible depth of detection.
In 2017, Chinese scientists claimed to have made a breakthrough in magnetic detection technology with a device that can monitor tiny disturbances in the Earth’s magnetic field caused by metallic objects such as submarines.
Researchers are also working on sensors using cutting-edge quantum technology to chase the gravitational abnormality that a submarine creates in a large body of water.
Powerful listening devices have also been planted in strategic seabeds near the American naval base in Guam and in the South China Sea, some of which can “hear” low-frequency sounds from more than 1,000km away.
In Qingdao, researchers are working on an exascale supercomputer called “Deep Blue Brain” that, when completed in 2020, aims to be the most powerful computer in the world.
The supercomputer will then use the masses of data along with artificial intelligence to recreate the world’s oceans, in unprecedented detail, in digital form. It will have a high-resolution virtual ocean.