BURSTA group of Chinese researchers just made a discovery that could threaten the security of the U.S.
A member of the incoming U.S. presidential administration in particular might take issue with their findings.
According to the South China Morning Post, a team of researchers was able to detect a drone with a profile similar to that of a stealth fighter, even though it was not emitting radio waves. The drone, which was chosen because it has the same radar profile as a stealth fighter like a F-35 or F-22, was detected because it cast a shadow against the radiation emitted by a satellite. In this case, it was one of the satellites in the Starlink constellation owned and operated by Elon Musk’s SpaceX.
Instead of being detected by radio waves, the drone reportedly was illuminated by electromagnetic radiation emitted by a Starlink satellite flying above the Philippines.
If true, these claims would represent a game-changing feat. No country has yet been able to detect stealth aircraft in this way, and the ability to do so immediately calls into question the efficacy of any stealth aircraft against which this technique is being used.
To understand why, it helps to understand the unique nature of stealth aircraft.
In the past, military airplanes were designed for speed, said Vladik Kreinovich, a professor of computer science at the University of Texas at El Paso. They were built with a smooth, geometric shape to minimize aerodynamic resistance. To detect such aircraft, radar was (and is) used to send beams of electromagnetic waves in their direction. The beams hit the plane and reflect back in the direction they came (in this case, in the direction of the radar station, which can then register the aircraft’s position).
Stealth aircraft, on the other hand, fly “under the radar.” Thanks to their unique shapes and the advanced chemistry used to coat their hulls, a radio wave beamed at them is far less likely to reflect back in the direction of the radar station. Instead, it reflects in all different directions due to the geometric shapes of the hull—or gets dampened or absorbed by the materials on the hull.
“Creative engineers realized that if we make the airplane surface out of planar parts—like a Tesla Cybertruck—then each planar part will reflect the beam in only one direction, and it will be highly improbable that one of these few reflected directions will go back to the radar location,” Kreinovich explained.
Stealth aircraft sacrifice the speed of more detectable planes in order to remain, in essence, invisible. Usually, that’s a decent tradeoff, but not this time. In light of the new research, the very features that typically make the stealth aircraft invisible could actually make it vulnerable if the claims of the researchers are true, said Kreinovich.
“When a stealth aircraft is on the path from a satellite to the ground station, the satellite signal is decreased, by reflection and absorption,” he said. “In principle, you can detect that.”
In other words, the stealth aircraft’s defenses against radar are ineffective, because the radar isn’t being used to detect them. Instead, their profile against a third-party backdrop (in this case, the Starlink satellite) is what gives them away.
To be fair, a stealth aircraft is not the only thing that can cause the results observed by the researchers, Kreinovich noted. Normal atmospheric phenomena or normal planes can produce the same effect. But if the radar doesn’t detect anything along its path and the disruption is still occurring, there is a “high possibility” that the signal decrease is caused by a stealth plane or drone.
In addition to detecting stealth aircraft, this approach also has the added benefit of helping radar systems themselves avoid detection. After all, sending out a signal to detect stealth aircraft can reveal the location of radar and lead to jamming efforts from a hostile force. However, avoiding sending out a signal entirely could both reveal adversaries and keep their radar stations hidden.
The implications of this detection technique are profound.
The Starlink satellite network currently consists of around 7,000 satellites, which already provide near-global coverage. But Starlink launches more nearly every day and has plans to expand to over 40,000 satellites in orbit simultaneously. These satellites operate in low Earth orbit (LEO) at altitudes of anywhere from about 300 to 600 km and orbit the planet every 90 minutes.
Given that, all countries that possess advanced stealth aircraft could find themselves at a disadvantage. That group, right now, is an exclusive club. It consists of the U.S. and its allies, as well as China and Russia. This means the U.S. should be most concerned about this development, experts said, given the geopolitical competition between America and China.
When asked if the work of these researchers is something that the U.S. should be paying attention to, Bahman Zohuri, an adjunct professor at Golden Gate University and a veteran semiconductor and defense researcher, is unequivocal.
“Absolutely,” he said. “I would take them very seriously.”
However, there may be a silver lining (if you’re a stealth pilot): even if this research is validated and fully deployed, it may not be the end of stealth, said Kreinovich.
“Countermeasures are possible. The very experiment shows one of the possible countermeasures: since in this experiment, a drone causes a similar image as a stealth plane, a natural idea is to accompany a stealth aircraft by a cloud of drones, thus confusing the detection system,” he said.
Despite the fact we’re talking about bleeding-edge research, this is actually a dance that has been happening since the beginning of air warfare, said Peter Westwick, a USC Dornsife professor who has written a book on the history of stealth.
The moment a new offensive or defensive technique is invented, the pendulum starts to swing back in the other direction as adversaries compensate for the upgrade in technology or strategy.
“Stealth represented a swing, and a long-lasting swing at that, to the offense having the advantage,” said Westwick. “It would not be surprising to see the defense regain some ground.”
Logan Kugler is a freelance technology writer based in Tampa, FL. He is a regular contributor to Communications and has written for nearly 100 major publications.