Precision, Non-Contact Metrology

The P-band antenna array is built from rows and columns of antenna elements for the purpose of allowing beam steering up to the maximum desirable angle without incurring grating lobes in the radiation patterns. For flexible mission planning, a large array can be built from several of the small, panel-like elements. The elements are deployable from a folded or stacked stowed configuration during launch, arranged side by side during operation. Each antenna element is itself a fully functional small antenna array. The number of panels can be chosen as dictated by the mission objectives and budget. Three geometries were designed and tested. Geometry 1 features non-planar metal structures with minimal dielectric support, where the back cavity is closed. Geometry 2 features non-planar metal structures with minimal composite sheet dielectric support, but with an open cavity. Both geometries avoid large flat sheets, which are vulnerable to bending, thereby increasing the mechanical stiffness of the structure while using only thin sheet metal and maintaining an exceptionally low mass-to-size ratio. Geometry 3 features planar metal structures, with sandwich composite dielectric support and an open cavity. While it does not benefit from the mechanical stiffness utilized in non-planar designs, the planar sandwich structure increase robustness and reduces the cost of fabrication. All element geometries have wideband capabilities and are dual polarized. Although designed for space and planetary exploration, the P-band antenna is also valuable for various terrestrial use cases. The P-band antenna array is at technology readiness level (TRL) 5 (component and/or breadboard validation in relevant environment) and is available for patent licensing.

NASA Goddard Space Flight Center has developed a 3D lidar system that consists of microelectromechanical systems (MEMS) beam steering, high performance reconfigurable computing, and an in-depth understanding of systems level integration. Kodiak combines a 3D MEMS scanning lidar with a long range narrow FOV telescope to produce a flexible and capable space flight ranging system. Also included is SpaceCube-level processing power to host a variety of algorithms enabling sensing and 6 degrees of freedom.

NASA’s imaging system is comprised of a small CMOS camera fitted with a C-mount lens affixed to a 3D-printed mount. Light from the high-intensity LED is passed through a lens that both diffuses and collimates the LED output, and this light is coupled onto the cameras optical axis using a 50:50 beam-splitting prism. Use of the collimating/diffusing lens to condition the LED output provides for an illumination source that is of similar diameter to the camera’s imaging lens. This is the feature that reduces or eliminates shadows that would otherwise be projected onto the subject plane as a result of refractive index variations in the imaged volume. By coupling the light from the LED unit onto the camera’s optical axis, reflections from windows – which are often present in wind tunnel facilities to allow for direct views of a test section – can be minimized or eliminated when the camera is placed at a small angle of incidence relative to the window’s surface. This effect is demonstrated in the image on the bottom left of the page. Eight imaging systems were fabricated and used for capturing background oriented schlieren (BOS) measurements of flow from a heat gun in the 11-by-11-foot test section of the NASA Ames Unitary Plan Wind Tunnel (see test setup on right). Two additional camera systems (not pictured) captured photogrammetry measurements.

Fabrication of NASA's pupil mask begins with the preparation of a silicon wafer, which serves as the foundation for the black silicon structure. The wafer undergoes ion beam figuring (IBF), a non-contact technique that precisely removes surface irregularities at the nanometer scale. This process ensures that the silicon surface is diffraction-limited, eliminating errors that could degrade optical performance. Once the wafer is polished to the required precision, it is then processed lithographically to define the mask pattern, creating reflective and absorptive regions essential for controlling light propagation. To achieve the desired high absorption characteristics, the lithographically patterned wafer undergoes cryogenic etching, a sophisticated process that transforms the silicon surface into a highly textured, black silicon structure. This method utilizes a controlled plasma environment with sulfur hexafluoride (SF6) and oxygen to etch the surface at cryogenic temperatures. The process is carefully optimized by adjusting parameters such as gas flow rates, chamber pressure, ion density, and etch duration, leading to the formation of high-aspect-ratio nanostructures on the silicon substrate. These structures, resembling a dense “forest” of silicon nanospikes, trap and diffuse incoming light, drastically reducing specular reflection. The resulting surface exhibits an ultra-low reflectivity that is orders of magnitude lower than conventional polished silicon. By leveraging NASA’s cutting-edge fabrication technique, the newly developed black silicon pupil mask offers a powerful solution for high-contrast astronomical imaging. Its ability to minimize scattered light and enhance optical contrast makes it an ideal component for space telescopes tasked with directly imaging exoplanets as well as other applications requiring ultra low reflectivity systems.

The Miniaturized Astrometric Alignment Sensor advances satellite capabilities for astrophysical measurements, necessary for formation flying, relative navigation, and virtual telescope capabilities. The sensor is a single assembly consisting of a small, low powered camera assembly. The sensor detects stellar objects from which both stellar and object tracking are performed. The sensors components consist of a low power camera assembly, interchangeable lenses, camera power supply, and image processing software and algorithms. The system functions by searching and identifying objects in the camera's field of view and tracking the objects against a selected star pattern with a central body of interest in the sensor's field of view. The Miniaturized Astrometric Alignment Sensor makes it possible to measure a spacecrafts altitude and orientation with respect to known stellar objects. The instrument takes an image of a patch of sky, identifies the stars in that field of view, and compares the field view with a stored star map. The data is processed with a dedicated processor attached to the instrument to spell out the attitude and orientation of a spacecraft.