A Chinese PL-10 air-to-air missile showing its heat-seeking head. Photo: Chinese Military Review

Chinese scientists are developing a heat-seeking hypersonic weapon that could hit a car-sized target, potentially expanding the application of these weapons from strategic nuclear deterrent to tactical precision weapons in a regional conflict.  

A research team from the PLA Rocket Force University of Engineering in Xian has been given until 2025 to solve problems associated with developing a new heat-seeking guidance system. 

The team discussed these problems and their solutions in a paper published in the Chinese peer-reviewed journal Infrared and Laser Engineering. They said that since hypersonic missiles travel great distances in short amounts of time, a tiny error in their guidance systems could throw them significantly off-target.

At such distances, a target’s infrared signature may consist of “just a few pixels without any detailed information, such as shape, texture and structure,” making target tracking and identification “extremely difficult.”

Also, heat-seeking sensors require extremely cold environments to function, which is a problem during hypersonic flight. During hypersonic flight, a plasma layer hotter than the surface of the sun forms on the missile’s skin, which degrades the accuracy of traditional heat-seeking sensors. 

Research team leader Yang Xiaogang discussed his team’s solutions to overcoming these technical challenges. Traditional heat seekers do frame-by-frame analysis of images, which during hypersonic flight results in two frames having huge differences with each other.

In contrast, their new method uses data collected by motion sensors to adjust every pixel to ensure consistency between earlier shots in terms of viewing angle, lighting or size.  According to the team, this complex calibration technology produces a more stable background image that makes the target stand out more distinctly.

China flaunts its hypersonic prowess in the Dongfeng-17 hypersonic glider during a military parade in Beijing in a file photo. Photo: AFP

New sensor technology

In addition, enhanced heat-seeking technology can enable surface-to-air use of hypersonic weapons. A separate team from Xidian University demonstrated new sensor technology which enables heat signatures to be detected over distance as a unique wave form, even at hypersonic speeds.

This enables a hypersonic missile to hit an aerial target as small as a conventional drone, with the missile able to distinguish the low-flying drone from buildings and trees with 90% accuracy.

The team also said they have found low-cost substitutes for precious materials needed for hypersonic guidance systems. Glass made of zinc sulphide can replace diamond for the windows of infrared detectors, providing crystal-clear images at a fraction of the cost. 

At present, China’s hypersonic missiles have a large circular error probable (CEP), which restricts their use to large targets such as cities and military bases, potentially confining their use to strategic nuclear deterrence.

China’s hypersonic weapon test last August showed its missile missed its target by two dozen miles, an unacceptable level of accuracy for attacking maneuvering targets such as warships. 

Despite this initial poor level of accuracy, China has been improving the accuracy of its hypersonic arsenal against moving tactical targets. Last year, satellite imagery showed China had built a rail-mounted aircraft carrier practice target in the Taklamakan Desert, ostensibly to simulate a moving target against various anti-ship missiles, including hypersonic weapons.

However, moving warships out on the open seas are relatively large targets to detect and track, considering their size and stable background. Cluttered environments such as sea lanes of communication (SLOCs), naval bases and littoral areas increase the difficulty of targeting, providing lots of false returns to targeting systems. 

This improvement in hypersonic guidance systems can potentially make the weapons more potent in crowded, target-rich environments. Such pinpoint-level accuracy is necessary for a future Pearl Harbor-style missile attack on enemy warships and naval facilities to distinguish critical targets from potentially unimportant ones. 

This US Navy photo shows the aircraft carrier USS Theodore Roosevelt, front, the Arleigh Burke-class guided-missile destroyer USS Russell, center, and the Ticonderoga-class guided-missile cruiser USS Bunker Hill transit in formation on July 31, 2019, in the Pacific Ocean. Photo: AFP / Anthony J Rivera / Navy Office of Information

Mock-up US warship targets

China appears to be preparing for such a scenario by constructing missile target mock-ups of US warships and Taiwanese naval base facilities, with the warship and base targets appearing to be made of different materials from each other, possibly to simulate different heat and radar signatures in a crowded target-rich environment.

Improved guidance systems could distinguish between these different signatures and guide hypersonic weapons to their intended targets with pinpoint accuracy. 

Apart from improving the quality of its guidance systems, China is developing onboard AI for its hypersonic weapons, a move that can potentially increase their accuracy by 10 times.

This development aims to give more decision-making capabilities to the smart weapon, with its human controllers having no idea how it will behave after launch, but still substantially increasing its accuracy.

Conventional missiles are pre-programmed from the factory floor, and their accuracy depends on how precisely it can determine its own position while making complex maneuvers.

However, as the missile’s skin heats up and a plasma layer forms during hypersonic flight, it is rendered blind and deaf to satellite signals or the Earth’s magnetic field for positioning data. This forces the missile to rely on its onboard inertial sensors, which can only estimate its location.  

Also, routine handling and maintenance of hypersonic weapons causes minute changes in their carefully-calibrated guidance systems, causing further deviations from factory settings which can affect missile accuracy. 

Hence, the use of onboard AI may do away with factory settings, as it would work immediately after launch before the missile reaches hypersonic speeds. The AI would then calculate a unique positioning algorithm for the missile based on satellite data, onboard sensors and the actual condition of its guidance systems. 

These developments may serve to reduce the reliance of China’s hypersonic weapons on vulnerable satellite kill chains. Satellites are a potential vulnerability in the hypersonic kill chain, as they are relatively defenseless and cannot be repaired or replaced easily once damaged or destroyed.

As such, China’s use of multiple guidance systems featuring infrared, radar and AI aboard its hypersonic weapons provide redundant systems should mission-critical satellites be taken out during a regional conflict in the Pacific.