Summary in Seconds:
Chinese researchers claim to have developed an ultra-thin stealth coating made from carbonized loofah and magnetic nanoparticles that absorbs more than 99.99 percent of radar waves used by satellite detection systems. The material’s natural, sponge-like structure traps and dissipates electromagnetic energy, sharply reducing an aircraft’s radar signature. The study highlights an unexpected fusion of biomimicry, sustainability, and advanced military technology.
In a striking blend of nature and advanced military science, Chinese researchers claim to have developed a new stealth coating that could make fighter aircraft far harder to detect by U.S. space-based radar satellites [1]. The innovation, reportedly developed by research teams working with the People’s Liberation Army (PLA) and the China Aerospace Science and Industry Corporation (CASIC), is based on an unlikely natural material: the loofah [2].
Loofah, best known worldwide as a humble bathing sponge or household cleaning tool, is derived from the dried fruit of a tropical gourd in the cucumber family. Yet beneath its everyday simplicity lies a complex natural architecture. Its fibrous, sponge-like structure forms a dense three-dimensional network of interconnected cellulose fibers—an arrangement that, when transformed under extreme conditions, can become something far more sophisticated.
According to reports by the South China Morning Post and a study published in the Chinese scientific journal High Power Laser and Particle Beams, researchers led by Chen Jun at CASIC’s Guizhou Aerospace Metrology and Testing Technology Institute converted dried loofah into carbon through hydrothermal treatment [3] and high-temperature carbonization [4]. They then embedded this carbonized structure with magnetic nanoparticles [5] of nickel cobalt oxide, creating a composite material known as NCO-2 [6].
The result is an ultra-thin microwave-absorbing coating only 4 millimeters thick. Despite its thinness, the material reportedly absorbs more than 99.99 percent of incoming electromagnetic waves in the Ku-band [7], a frequency range between 12 and 18 gigahertz that is widely used by modern radar satellites. Tests suggest that the coating can reduce reflected radar signals by nearly 700 times, even when radar beams strike an aircraft directly from above—a scenario that traditionally poses significant challenges for stealth design.
The secret lies in how electromagnetic waves behave once they encounter the coating. Instead of reflecting back to the radar source, the waves enter the material’s maze-like pores and bounce around internally. Each reflection gives the material more time to absorb the energy. At the same time, the conductive carbon network allows electrons to move freely, converting microwave energy into heat, while the magnetic nanoparticles enhance magnetic loss. Together, these effects—conductive loss [8], magnetic loss [9], interfacial polarization [10], and optimized impedance matching [11]—work in concert to dramatically weaken radar returns.
In practical terms, the researchers claim that an aircraft with a vertical radar cross-section of 50 square meters could see its detectable signature reduced to less than one square meter after being treated with this coating. Such a reduction would make the aircraft significantly harder to track from space.
Beyond its military implications, the research team highlights another intriguing dimension of the work: sustainability. Because loofah is a renewable, biomass-derived material, the study presents what the researchers describe as a “green” pathway toward high-performance electromagnetic wave–absorbing composites. It is a curious twist of history that a plant possibly used by ancient Egyptians—reportedly even during the time of Queen Cleopatra—has now become the basis for cutting-edge stealth technology.
Verified through advanced simulations using COMSOL engineering software, the study reflects a growing trend in modern science: drawing inspiration from natural structures to solve complex technological challenges. Whether this loofah-based coating will live up to its bold claims in real-world combat conditions remains to be seen. Still, the idea that a simple gourd could help hide fighter jets from orbiting radar satellites is a vivid reminder that innovation often emerges from the most unexpected places—where nature and technology quietly meet in a new light.
Notes
1. Space-based radar satellites — These are satellites orbiting Earth that use radar signals to detect and track objects on the ground or in the air. They send out radio waves and analyze the signals that bounce back to identify aircraft, ships, or terrain.
2. The loofah — A loofah is a natural sponge made from the dried fruit of a plant in the gourd family. Its lightweight, fibrous structure forms a complex network of pores that can be useful beyond bathing and cleaning.
3. Hydrothermal treatment — This is a process that uses hot water and high pressure to change the structure of a material. It helps break down natural fibers and prepares them for further chemical or physical transformation.
4. High-temperature carbonization — Carbonization is the process of heating a material to very high temperatures in the absence of oxygen. This turns organic matter into carbon, making it electrically conductive and more resistant to heat.
5. Magnetic nanoparticles — These are extremely tiny particles—thousands of times smaller than a grain of sand—that respond to magnetic fields. When added to materials, they help absorb and weaken electromagnetic energy.
6. NCO-2—is a novel, ultra-thin, microwave-absorbing composite material developed by Chinese scientists, created by embedding nickel cobalt oxide (NiCo₂O₄) nanoparticles into a carbonized loofah (cellulose) scaffold, forming a porous 3D network that significantly reduces radar signals, making stealth aircraft harder to detect, especially in the Ku band, by trapping and dissipating electromagnetic waves.
7. Electromagnetic waves in the Ku-band — These are high-frequency radio waves commonly used by radar and communication satellites. Because they can detect fine details, they are especially useful for tracking aircraft from space.
8. Conductive loss — This occurs when electrical energy moves through a conductive material and is converted into heat. In stealth materials, this process helps absorb radar signals instead of reflecting them back.
9. Magnetic loss — Magnetic loss occurs when magnetic materials absorb energy from electromagnetic waves. This absorption weakens the radar signal and reduces how much energy is reflected.
10. Interfacial polarization — This effect occurs at the boundaries between different materials inside a composite. Electric charges build up at these boundaries, helping trap and absorb electromagnetic energy.
11. Optimized impedance matching — This means designing a material so electromagnetic waves can easily enter it rather than bouncing off the surface. Better impedance matching allows the material to absorb more radar energy and remain harder to detect.
Sources
Johnson, Reuben. “China’s Stealth Fighters Might Soon Be Invisible to Space-Based Radar.” 1945, December 6, 2025.
https://www.19fortyfive.com/2025/12/chinas-stealth-fighters-might-soon-be-invisible-to-space-based-radar/
Mishra, Prabhat R. “China’s New Stealth Jet Coating Made from Loofah Reduces Radar Signal Intensity by 700x.” Interesting Engineering, November 27, 2025.
https://interestingengineering.com/military/china-stealth-fighter-jet-coating-radar-signals