Self-Cleaning Coatings for Space or Earth

Materials and Coatings
Self-Cleaning Coatings for Space or Earth (KSC-TOPS-99)
Transparent Electrodynamic Dust Shields Usable for Solar Cells
Overview
Reducing dust accumulation on any surface is key for lunar missions as dust can damage or impair the performance of everything from deployable systems to solar cells on the Moon’s surface. Electrodynamic dust shields (EDSs) are a key method to actively clean surfaces by running high voltages (but low currents) through electrodes on the surface. The forces generated by the voltage efficiently remove built up, electrically charged dust particles. Innovators at the NASA Kennedy Space Center have developed a new transparent EDS for removing dust from space and lunar solar cells among other transparent surfaces. The new coatings operate at half the voltage of existing EDSs while being 90% thinner. These capabilities are enabled by an innovative combination of electrode patterning and a thin silica protective layer. The reduced thickness and lower voltage operation expands possibilities for integrating EDSs onto transparent surfaces across industries.

The Technology
The new transparent EDS technology is lighter, easier to manufacture, and operates at a lower voltage than current transparent EDS technologies. The coating combines an optimized electrode pattern with a vapor deposited protective coating of SiO2 on top of the electrodes, which replaces either polymer layers or manually adhered cover glass (see figure on the right). The new technology has been shown to achieve similar performances (i.e., over 90% dust clearing efficiency) to previous technologies while being operated at half the voltage. The key improvement of the new EDS coating comes from an innovative method to successfully deposit a protective layer of SiO2 that is much thinner than typical cover glass. Using vapor deposition enables the new EDS to scale more successfully than other technologies that may require more manual manufacturing methods. The EDS here has been proven to reduce dust buildup well under vacuum and may be adapted for terrestrial uses where cleaning is done manually. The coatings could provide a significant improvement for dust removal of solar cells in regions (e.g., deserts) where dust buildup is inevitable, but water access is limited. The EDS may also be applicable for any transparent surface that must remain transparent in a harsh or dirty environment. The related patent is now available to license. Please note that NASA does not manufacturer products itself for commercial sale.
Examples of the EDS actively removing the dust from glass surfaces under vacuum when dust is placed by (a) a brush and (b) by a vacuum dust deposition system.
Benefits
  • Energy savings and enhanced safety: Operates at half the voltage of current EDS technologies.
  • High performance: Demonstrated over 90% dust removal efficiency.
  • Manufacturing scalability: Vapor deposition process enables large scale manufacturing.
  • Versatility: Applicable to a wide range of transparent surfaces including solar cells, glass, and other materials.

Applications
  • Aerospace: solar cells, windows for spacecraft and stations, or spacesuit visors
  • Terrestrial power: solar farms and rooftop solar panels
  • Architecture: building windows
  • Agriculture: windshields on farming equipment and windows or roofs of greenhouses
  • Automotive: headlights, windshields, mirrors, and sensors on vehicles
Technology Details

Materials and Coatings
KSC-TOPS-99
KSC-14465
Similar Results
sail boat
Particle Contamination Mitigation Methods
The following methods can be used individually or in combination to generate superhydrophobic surfaces: Synthesis of novel copolyimide oxetanes with unique surface properties The technology is the synthesis of a polyimide coating or film with a modified surface chemistry shown in Figure 1. A minor amount of an oxetane reactant containing fluorine is added to the polyimide, and the oxetane preferentially migrates to the surface, enabling relatively high concentrations of fluorine at the surface, without compromising the functional performance of the bulk of the polymide coating/film. The copolymers exhibit mitigation of particle adhesion and fouling from exposure to various particulate and biological contaminants and exhibit reduced surface energy and increased surface fluorine content at extremely low oxetane loadings relative to the imide matrix (see Figure 2). Additionally, the short fluorinated carbon chains do not bioaccumulate, reducing the environmental impact of these materials. Modifying surface energy via laser ablative surface patterning This method uses a laser to create nanoscale patterns in the surface of a material to increase the hydrophobicity of the surface (see Figure 2). The benefits of hydrophobic surfaces include decreases in friction and increases in self-cleaning properties. This is an advantageous method of surface modification because it is fast and single-step, promises to be scalable, requires no chemicals, could be applied to a variety of materials, and does not require a planar surface for patterning.
Lotus Coating
Lotus Coating
This durable, transparent, nano-textured coating can be applied via a wet chemistry process to variety of rigid and flexible surfaces by spin coating, brush application, or spray application, making it applicable for many purposes beyond space flight and aeronautical applications. The coatings unique nano-textured surface and overcoat reduces surface energy and contact surface area, giving the coating anti-contamination and self cleaning properties that minimize dust, liquid, and ice accumulation on its surface, similar to a leaf on the Lotus plant. The coating is low outgassing, stable in vacuum, and can survive harsh spaceflight environments. Depending on requirements, the Lotus Coating can be tailored to fit the specific needs of a project or customer. This customization makes the Lotus system far more adaptive, allowing for a more diverse range of applications.
View through a P-3 window of a small grounded portion of the terminus of Upernavik Central, northwest Greenland, as seen during an Operation IceBridge flight
Alternative Transparent Coating Lotus Suitable for Optics with Vacuum Deposition Layer
In addition to previous LOTUS coating formulations, an additional optical formulation may be applied via vacuum deposition. This coating forms a top layer and may be applied in different thicknesses that serve to enhance its hydrophobic properties. The vacuum deposited material may comprise fluorinated ethylene propylene or a similar material. This coating is transparent and can be used on optical components or any other applications requiring a clear coating.
Astronauts on Planet Surface
Dust Tolerant Quick Disconnect With Self-Sealing Barrier
Dusty, dirty environments can be very tough on connectors. The abrasive nature of dust and dirt particles can rub and wear down connector surfaces through friction, and have a negative effect on coatings used on gaskets to seal equipment. Dust on umbilical connections can also make mating and de-mating electrical and fluid connections difficult, hazardous, and unreliable. NASA's Quick Disconnect (QD) design consists of columnar arrays of parallel filaments. All the pins of the electrical connector easily penetrate the barriers when the umbilicals are brought together. They are wiped clean of dust when they penetrate the barrier and mate cleanly and reliably. Likewise, the male end of a fluid connector penetrates the filament arrays of both connector ends. Since the filament arrays are oriented perpendicular to each other, the entire circumference of the connector is contacted by the filaments that stretch around, conform to, and sweep off dust from the mating surface ensuring a clean and secure connection.
Computer-implemented energy depletion radiation shielding
The difference between Layered Energy Depletion Radiation Shielding (LEDRS) and Stacked Energy Depletion Radiation Shielding (SEDRS) is how the piece of matter, or shield, is analyzed as radiation passes through the matter. SEDRS involves using a defined and ordered stack of layers of shielding with different material properties such that the thickness and chemical properties of each material maximizes the absorption of energy from the radiation particles that are most damaging to the target. The SEDRS shielding method aims to provide the maximum level of energy absorption while still keeping shielding mass and volume low. The process of LEDRS involves using layers of shielding material such that the thickness of each material is designed to absorb the maximum amount of energy from the radiation particles that are most damaging to the target after subsequent layers of shielding. The more energy is absorbed by the shielding material, the less energy will be deposited in the target minimizing the required mass to achieve a resulting lower dose for a given geometrical feature. The LEDRS shielding method aims to provide the maximum level of energy absorption. The process for designing LEDRS views potential radiation shields as a cascade of effects from each shielding layer to the next and is helpful for investigating the particular effects of each layer. SEDRS and LEDRS can improve any technology that relies on the controlled manipulation of a radiation field by interaction with a material element.
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