By Smart Material Solutions, Inc.
Smart Material Solutions has been working for five years on scaling so-called “functional surface textures.” Nanostructures on a surface dramatically affect how that surface interacts with the environment. For instance, texturing a surface with nanoscale features can make the surface self-cleaning via the lotus effect or decrease the adhesion of dust to a surface. This provides an opportunity for a passive solution to the dust problem. Passive solutions require no power or increase in payload mass, unlike, for example, an air spray, windshield wiper, vibrating panel, electrodynamic dust shield, or other proposed “active” solutions. Nanostructures essentially place the tiny micro-dust particles on a bed of nails, as shown in Figure 1. This reduces the contact area and the microscale adhesion forces, such as Van der Waals forces. The spacing between the nanostructures is important. It determines whether a dust particle will sit on top of multiple features, as desired, or whether it will stick between them, effectively making the problem worse. Figure 1 - Large dust particles (left) sit on top of the features of a textured surface (desirable), while small dust particles (right) can fall in between the features (undesirable). Figure 2 - Sharper features (right) have a smaller contact area and thus reduced adhesion. These geometric properties combine with material properties like hardness, surface energy, and electrical conductivity to determine a surface's passive affinity for dust. Unfortunately, due to the harsh realities of the lunar environment, including unfettered UV exposure and 200 degree temperature swings, the materials available for texturing are limited and typically so robust that they’re hard to pattern through the typical thermal embossing or UV curing processes. Solving this problem, at scale, is the goal of SMS’s NASA-sponsored SBIR Project. Figure 3 shows exciting preliminary results from this project.
