China may have cracked the code to track US submarines — using bubbles

Aircraft carriers may be the pinnacle of power on the surface, but no modern navy is complete without submarines. The underwater craft rely on stealth to stay alive, but researchers in China may have just blown that ability to stay hidden out of the water.

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China, the United States and Russia have the most submarines operating today. Now, other nations are beefing up their own fleets.

The French navy just put its second Suffren-class nuclear attack sub into the water. Suffren-class boats outperform their predecessors in every way. They’re faster, can stay under longer and perform a wider variety of missions, including attacking land-based targets with naval cruise missiles.

Israel’s submarine fleet now has five hulls in its inventory. Israel’s navy quietly launched its newest sub, the INS Drakon, recently. What the Israeli navy lacks in size it makes up for in ingenuity. The INS Drakon is rumored to be the first submarine in the world with modern missiles in its sail.

Future Israeli Navy Dolphin-class Batch-II submarine INS Drakon in Kiel, Germany – August 2, 2023 #insdrakon

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— WarshipCam (@WarshipCam) August 2, 2023

Known as the “Silent Service” during World War II, the U.S. Navy’s submarine fleet is vital to maintaining peace on the high seas. The ability to offer quick-strike capabilities against a range of targets all over the globe also ensures submarines play a vital role when it comes to deterrence.

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But if U.S. enemies know where the country’s subs are, the Silent Service won’t be the same deterrent it’s been for decades. It sounds like scientists in China may have just cracked that code.

Reporting from the South China Morning Post showed a team of researchers from the Chinese Academy of Sciences’ Fujian Institute of Research on the Structure of Matter made the discovery. Led by Zou Shengnan, the team’s findings were published in one of China’s most respected peer-reviewed scientific journals.

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Through computer modeling, the team showed it’s possible to track submarines, from long distances away, while they cruise underwater.

By using a highly sensitive magnetic detector, the researchers showed they could detect the electromagnetic frequency of the small bubbles created when nuclear powered submarines transit the seas below the surface, a process called the magnetohydrodynamic effect.

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It’s a currently unavoidable effect when submarines travel at speed underwater. Over time, the bubbles come together to create larger pockets of air. As those pockets leave the surface of the submarine, the higher pressure of the surrounding water causes the air pockets to collapse violently. This collapse creates feint, but observable, electromagnetic frequencies that are detectable in the extremely low frequency range from 9.94 Hz to 34.19 Hz. Signals in this range can penetrate the water and reach the ionosphere before being reflected back to the surface of the Earth.

According to the Chinese researchers, computer modeling showed “significant induced electric field signals can be observed around the bow, stern and rear of the hull” of submarines.  

In its paper, the research team does point out there are limitations when tracking subs using this new method. If the boat slows down or stops, it’s not creating any bubbles to track. Other naturally occurring or man-made electromagnetic noises can also interfere with the tracking process.