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Laser Structuring for Thermal Management in Aerospace Applications
The Fraunhofer Institute for Telecommunications is developing laser-based surface functionalization technologies to optimize heat dissipation for satellite components and rocket nozzles.
www.fraunhofer.de
Fraunhofer HHI has introduced a method for treating the outer surfaces of aerospace components using femtosecond and nanosecond lasers. This technology improves passive thermal management by increasing the emissivity of metal substrates, addressing cooling challenges in vacuum environments where thermal conduction is absent. The primary applications for this technology include space-capable power electronics, satellite outer walls, and rocket nozzles.
Vacuum Thermal Management Challenges
Electronics and structural components operating in space cannot rely on thermal conduction or convection for cooling due to the surrounding vacuum. Heat dissipation must occur exclusively through thermal radiation. Untreated, smooth metal surfaces such as aluminum possess a low thermal emissivity of approximately 10 percent, making them inefficient radiators.
To resolve this limitation, researchers developed a passive cooling method that modifies the physical topography of the metal without altering its chemical composition. By utilizing a femtosecond laser with short pulse durations, the process vaporizes specific areas of the surface while keeping the underlying bulk material undamaged. This laser-etching process creates microstructures, specifically cones measuring approximately one micrometer in size, which transform the smooth metal into a high-emissivity radiator.
Performance Evaluation and Material Characteristics
The laser-structuring process increases the thermal emissivity of aluminum, stainless steel, titanium, and copper to values between 95 percent and 99 percent. This represents an increase from the 10 percent emissivity benchmark of untreated bare metals.
The structural modification offers several functional advantages over traditional thermal control coatings:
- Thermal Stability: The structured aluminum surfaces remained stable during testing at temperatures up to 650 degrees Celsius. The functionalized surfaces maintain structural integrity up to the melting point of the host metal.
- Mass Reduction: Eliminating traditional paint coatings reduces the total launch weight of carrier rockets, lowering launch costs.
- Outgassing Prevention: Unlike chemical coatings or paints, the laser-structured metal does not release solvents or volatile compounds over time, eliminating the risk of outgassing in a vacuum.
The current iteration of the laser-treated surface appears black, which absorbs solar radiation when exposed to direct sunlight. Ongoing research aims to adapt the functionalization process to create white surfaces capable of reflecting sunlight while maintaining high emissivity.
Thermal test of a stainless steel de Laval nozzle
Alternative Processing Methods and In-Orbit Testing
To lower production costs, a parallel manufacturing process was developed in collaboration with Azimut Space GmbH. This approach replaces the precise femtosecond lasers with more cost-effective nanosecond laser processes. By executing the nanosecond laser treatment under a reactive gas atmosphere of pure oxygen, the system generates comparable surface structures. While this alternative method reduces the resulting thermal emissivity to approximately 85 percent, it decreases initial equipment investment costs.
The durability of these high thermal-emissivity surfaces has been tested under real-world conditions. In cooperation with the European Space Agency (ESA) and Azimut Space GmbH, laser-structured aluminum and titanium specimens were mounted on the outer hull of the International Space Station (ISS) in December 2024 to serve as radiative heat sinks. These material specimens are currently returning to Earth for analysis regarding material aging, structural degradation, and variations in thermal radiation performance.
The underlying high-emissivity surface structures were demonstrated at the joint Fraunhofer booth during the ILA 2026 aerospace trade show, which took place from June 2 to June 6, 2026, in Berlin, Germany.
Seamless high-emissivity laser-textured aluminum box for electronic components
Additional Context: Technical Specifications and Competitive Benchmarking
Passive thermal control in aerospace applications historically relies on optical coatings, thermal control paints (such as zinc oxide-based white paints), or Multi-Layer Insulation (MLI). Traditional high-emissivity coatings like Aeroglaze or AZ-93 achieve thermal emissivity values between 85 percent and 92 percent. However, these coatings are susceptible to degradation from ultraviolet (UV) radiation and atomic oxygen in Low Earth Orbit (LEO), leading to paint peeling, cracking, and outgassing. The outgassing of volatile organic compounds can condense on sensitive satellite optics and solar panels, degrading performance.
In comparison, direct laser surface structuring (DLSS) achieves higher emissivity values (95 percent to 99 percent) by altering the topography of the native substrate itself. Because no secondary material is applied, the risk of adhesion failure or outgassing is eliminated. While traditional coatings add mass to the spacecraft, laser functionalization removes micro-scale amounts of material, resulting in a net mass reduction. The primary limitation of DLSS compared to traditional coatings remains processing throughput, as laser-scanning large surface areas requires more manufacturing time than spray-applied chemical coatings.
Edited by Evgeny Churilov, Induportals Media - Adapted by AI.
www.fraunhofer.de
Thermal test of a stainless steel de Laval nozzle
Alternative Processing Methods and In-Orbit Testing
To lower production costs, a parallel manufacturing process was developed in collaboration with Azimut Space GmbH. This approach replaces the precise femtosecond lasers with more cost-effective nanosecond laser processes. By executing the nanosecond laser treatment under a reactive gas atmosphere of pure oxygen, the system generates comparable surface structures. While this alternative method reduces the resulting thermal emissivity to approximately 85 percent, it decreases initial equipment investment costs.
The durability of these high thermal-emissivity surfaces has been tested under real-world conditions. In cooperation with the European Space Agency (ESA) and Azimut Space GmbH, laser-structured aluminum and titanium specimens were mounted on the outer hull of the International Space Station (ISS) in December 2024 to serve as radiative heat sinks. These material specimens are currently returning to Earth for analysis regarding material aging, structural degradation, and variations in thermal radiation performance.
The underlying high-emissivity surface structures were demonstrated at the joint Fraunhofer booth during the ILA 2026 aerospace trade show, which took place from June 2 to June 6, 2026, in Berlin, Germany.
Seamless high-emissivity laser-textured aluminum box for electronic components
Additional Context: Technical Specifications and Competitive Benchmarking
Passive thermal control in aerospace applications historically relies on optical coatings, thermal control paints (such as zinc oxide-based white paints), or Multi-Layer Insulation (MLI). Traditional high-emissivity coatings like Aeroglaze or AZ-93 achieve thermal emissivity values between 85 percent and 92 percent. However, these coatings are susceptible to degradation from ultraviolet (UV) radiation and atomic oxygen in Low Earth Orbit (LEO), leading to paint peeling, cracking, and outgassing. The outgassing of volatile organic compounds can condense on sensitive satellite optics and solar panels, degrading performance.
In comparison, direct laser surface structuring (DLSS) achieves higher emissivity values (95 percent to 99 percent) by altering the topography of the native substrate itself. Because no secondary material is applied, the risk of adhesion failure or outgassing is eliminated. While traditional coatings add mass to the spacecraft, laser functionalization removes micro-scale amounts of material, resulting in a net mass reduction. The primary limitation of DLSS compared to traditional coatings remains processing throughput, as laser-scanning large surface areas requires more manufacturing time than spray-applied chemical coatings.
Edited by Evgeny Churilov, Induportals Media - Adapted by AI.
www.fraunhofer.de
