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Radio communications apertures for spacecraft have long been implemented using deployable architectures in order to fit within the allowable launch vehicle volume. Apertures for optics missions have traditionally not been segmented because of the tight requirements on the deployed surface. By the nature of the problem, larger apertures are generally better, but complicate orbital delivery. While there are several reflectors commercially available, high packing ratios come at very high cost due to the extremely complex nature of the designs. Researchers at the Space Vehicles Directorate have been investigating ways to enable high packing ratios while reducing the design, integration, and testing complexity of deployable systems, thereby driving down cost and enabling greater mission capabilities. Recent advances in flexible composites have opened up the possibilities of packaging apertures using either distributed or concentrated strain. This paper offers an overview of recent work done to enable lower complexity deployable apertures. Several origami-inspired designs are presented including a flat spiral folding membrane, a parabolic antenna reflector, and a phased array structure.

State of the art radio frequency (RF) arrays are growing larger in pursuit of increased signal-to-noise ratio. In support of this goal, elaborate forms of metrology are being developed to support the increased footprints. This work provides a unique solution to fulfill the metrology requirements of large-scale deployable RF antennas through the implementation of neural network demodulation of fiber optic strain sensors. The fiber optics are patterned with Fiber Bragg Gratings (FBGs) to encode strain on to back-reflected shifts in the wavelength of incident light. Experiments show the neural network can predict the deformation of a test structure within single millimeters for small amplitude motions. Therefore, the current technique meets the required lambda/20 precision needed for large scale deployable RF arrays operating at S-band or longer wavelengths.

Solder self-alignment is an important phenomenon enabling cost-effective optoelectronics assembly. In this study, the wetting of Sn-rich solder to under bump metallization (UBM) pads is identified as a critical factor affecting self-alignment accuracy. Incomplete wetting of solder to the metallization pads is responsible for chip-to-substrate misalignment larger than 1 μm, while fabrication tolerances, such as solder volume variation and pad diameter deviation, only account for misalignments in the submicron range. To quantitatively investigate the effect of incomplete wetting on self-alignment accuracy, a three-dimensional (3D) model based on a force optimization method was developed. With the input parameters of incomplete solder metallurgical wetting area, position and diameter of metallization pad, volume of individual solder bumps, coefficient of solder surface tension, mass of the chip, external forces acting on the chip, and initial pick-and-place position of the chip before assembly, the model predicts the assembled position of the chip in terms of the misalignments in the X-Y plane and the rotation angle along the Z axis. The model further confirmed that incomplete wetting of solder is the most critical modulator among the undesirable factors affecting solder self-alignment accuracy.