Can China thwart US hypersonic missile defence systems with an old algorithm?

Chinese military scientists say they have developed a method to help hypersonic weapons evade interception while using minimal resources
It could allow Beijing to obtain lots of information about Washington’s defence systems, according to paper

Science

Stephen Chenin Beijing

Published: 12:00pm, 29 Apr 2023

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Chinese scientists with the People’s Liberation Army (PLA) say they have developed a technology based on a simple algorithm that can thwart the world’s most advanced hypersonic missile interception systems.

China’s heat-seeking hypersonic weapons use infrared sensors to help them home in on a moving target such as a warship. The sensors can also be used to identify and track an intercepting missile.

Researchers led by engineer Zhang Xuesong with the PLA Strategic Support Force Information Engineering University say they have developed an algorithm that can analyse the trajectory of these hypersonic weapons to help them avoid missile defence systems, including advanced systems under development in the United States.

Computer models simulating hypersonic strikes at eight times the speed of sound, or Mach 8, suggested that Zhang’s method could help China’s hypersonic weapons evade interception while minimising the amount of resources needed for calculations, according to a paper published in the Chinese journal Common Control and Simulation last month.

This could give China an advantage in any potential conflict involving hypersonic weapons, though the actual capabilities of China’s hypersonic weapons and their ability to evade US missile defence systems are not publicly known.

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Evading missile defence systems is a challenging task because heat detectors in China’s hypersonic weapons are only able to see intercepting missiles from a limited perspective, and this usually does not provide enough information to accurately determine the interceptor’s location.

“You might have an idea, but you can’t be sure exactly where it is,” said a space scientist not involved in the study who requested anonymity because of the sensitivity of the subject.

The method proposed by Zhang’s team is based on multi-model adaptive estimation (MMAE), a statistical algorithm commonly used in control systems engineering to make estimates when observations are incomplete or inaccurate.

MMAE has been around for decades and has been used in various applications, including missile defence.

While other researchers have proposed using AI to solve complex problems in hypersonic missile defence, Zhang’s team argued that the older MMAE method still worked well – with some small tweaks.

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According to the researchers, China has already obtained a lot of information about US missile defence systems such as their radar stations, launch locations, propellants and even the model of rocket engine used by the intercepting missiles. But they do not know the mathematical model used by an intercepting missile as it engages a target.

Zhang’s team said their algorithm could determine the model and certain secret design parameters of an enemy interceptor within 10 minutes of its launch and estimate its trajectory to within about five metres (16ft) of accuracy.

“This is faster and more accurate than other approaches,” the researchers said.

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The development of hypersonic weapons has been a major focus for both China and the US in recent years, as these weapons are seen as potential game-changers in modern warfare.

The Chinese and Russian militaries have deployed various types of hypersonic weapons that can travel long distances at Mach 5 or faster. China’s YJ-21 missile, for instance, is designed to penetrate heavy air defence and hit an aircraft carrier moving at full speed.

If one country is able to develop effective defences against hypersonic threats while the other is not, it could upset the balance of power and potentially accelerate an arms race as each side seeks to catch up, according to military experts.

Washington has prioritised military spending to develop new defence capabilities against Chinese and Russian hypersonic weapons. Its Next Generation Interceptor (NGI), for instance, will feature interceptor missiles that are faster, more manoeuvrable, and more reliable than predecessors designed to destroy ballistic missiles.

The NGI missile is designed to launch from a ground-based silo and use its own sensor to locate and track incoming hypersonic missiles. Its interceptor will use an advanced guidance system to destroy its target in space.

Major defence contractors including Boeing, Lockheed Martin, Raytheon and Northrop Grumman have taken part in the NGI programme. The total investment remains unknown, but some military experts have estimated that it could cost US taxpayers billions of dollars.

Some Chinese military researchers say that if China had hypersonic missiles with conventional warheads capable of destroying high-value military targets at sea or on land, it could intimidate the US and deter it from starting a military conflict in the Taiwan Strait, the South China Sea or other sensitive areas.

But other experts have warned that the race to develop hypersonic missiles and other advanced weapons systems could potentially undermine the effectiveness of existing missile defence systems and increase the risk of miscalculation or unintended escalation.