The era of the “silent service” is coming to an end, as new technologies are making even the most advanced nuclear and diesel-electric submarines vulnerable to detection.
For decades, submarines have relied on their stealth as their primary defense, but this advantage is eroding.
Emerging anti-submarine warfare (ASW) techniques, including vast undersea sensor networks, satellite-based Lidar, and magnetic anomaly detectors, are making the oceans transparent.
This technological shift, coupled with the threat of autonomous underwater drone swarms, means the hunter is about to have the upper hand over the hunted.
The Shoe Is on the Other Foot: No More Hiding for Submarines
Submarines of many different types are stealthy by their nature. Modern undersea warfare is full of subs that are either nuclear-powered or are diesel-electric variants with Stirling air-independent propulsion systems. These boats can sneak around enemy defenses while avoiding sonar, rarely surfacing as they prowl around the globe undetected.
Catching a Tiger By the Tail
Past attempts at finding submarines with radar and active sonar were not very successful. Nuclear-powered ballistic missile subs (SSBNs) are particularly difficult to discover. This gives countries with SSBNs considerable advantages in first-strike or second-strike atomic war scenarios.
But the age of assured submarine stealth may be reaching its end. Subs still have some of the best noise-cancellation systems in the world. Acoustic signatures are kept to a minimum, and the days of rattles and hums that reveal a sub’s location are long over. Yet the cat-and-mouse game pitting subs against anti-submarine ships and aircraft could now be tilted toward the hunter-killers, while submarines, even those that are exquisitely quiet, come to face new threats.
The Days of Complete Submarine Stealth Are Over
New systems such as networks of acoustic hydrophone arrays that are attached to the bottom of the sea are much better at sniffing out submarines. Researchers at Australian National University’s National Security College believe that in the coming decades, even the best submarines will become discoverable by such arrays. By 2050, these scientists think, numerous subs will be found and sunk despite further advances in undersea warfare capabilities that keep boats stealthy.
Adversaries will keep improving their sub-hunting technologies. This can be accomplished with artificial intelligence and quantum computing systems that can find even the sneakiest enemy boats.
Rose Gottemoeller, former deputy secretary-general of NATO, warns that “the stealth of submarines will be difficult to sustain, as sensing of all kinds, in multiple spectra, in and out of the water becomes more ubiquitous.”
Sonar Can Be Eclipsed by New Technologies
Sonar may be an outdated means to find subs. Submarines also emit radiation and chemicals – small amounts to be sure, but enough output for the right system to track. There are also tiny disturbances in the Earth’s magnetic field that can be detected when submarines knife underwater. Plus, lasers or LED pulses can sense submarines, too. All of these anti-submarine systems will improve in the coming decades.
Meanwhile, submarines may have reached the pinnacle of their stealthiness. New submarines such as the Virginia-class attack boats from the U.S. Navy must last 60 years.
Anti-submarine warfare will improve so much by the end of their service lives that they will be discovered more easily with the new techniques.
IEEE.org has studied new ideas coming to undersea warfare that could turn back the clock on the advantages of submarines, making them once more as vulnerable as they were during the days of loud World War II-era diesel boats.
Australian National University
“According to experts at the Center for Strategic and International Studies, in Washington, D.C., two methods offer particular promise,” IIEE wrote. “Lidar sensors transmit laser pulses through the water to produce highly accurate 3D scans of objects. Magnetic anomaly detection (MAD) instruments monitor the Earth’s magnetic fields and can detect subtle disturbances caused by the metal hull of a submerged submarine.”
Of course there are many anomalies in the ocean, and the MAD instruments would have to do an amazing job at picking the right signal to discover a submarine. But these systems will only improve with time. It would take a hefty amount of scientific and engineering prowess to develop such techniques, but with highly motivated U.S. adversaries such as the Russians and the Chinese, these efforts could bear fruit in the coming years.
Space-based Lidar sensors are also promising, but they are expensive. Even so, with space warfare capabilities advancing so rapidly in China, the high prices could come down as more Chinese satellites are deployed.
Undersea Drones Rear Their Head
Undersea warfare conducted by drones is another possibility to seek and destroy submarines. A group of underwater drone swarms could be released by a remote-controlled submarine or surface vessel. These submerged drones would only need to be in the general vicinity of a specific search vector and could overwhelm a submarine’s defenses and crush its hull.
Chinese scientists have the kind of brainpower and government resources that could make these systems a reality. Submarines will likely not become any more quiet than they already are, which gives the future advantage to the searchers.
No navy can guarantee that its subs can completely avoid detection in the coming years with all of these promising technologies.
The days of full stealthiness could be over. We are not there yet, but the advantage lies with the country that can usher in a new era of undersea warfare – one that makes submarines easier to spot, track, and destroy.
About the Author: Dr. Brent M. Eastwood
Brent M. Eastwood, PhD is the author of Don’t Turn Your Back On the World: a Conservative Foreign Policy and Humans, Machines, and Data: Future Trends in Warfare plus two other books. Brent was the founder and CEO of a tech firm that predicted world events using artificial intelligence. He served as a legislative fellow for U.S. Senator Tim Scott and advised the senator on defense and foreign policy issues. He has taught at American University, George Washington University, and George Mason University. Brent is a former U.S. Army Infantry officer. He can be followed on X @BMEastwood.
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