Ultra lightweight structures for deployed optics

Future space missions, such as acquisition of high-resolution images in visible or near-visible wavelengths for space surveillance, target identification, and astronomy, require the deployment of space-based telescopes with large (greater than 4 m) effective apertures and with surface accuracy of better than 0.1 micron RMS. Current systems are limited not only by the physical size of the launch vehicle shroud, but also by the quality and alignment of the system after incurring stresses induced by launch. A large, lightweight, durable space telescope using precision deployable structures offers the potential for breakthroughs in high-resolution image acquisition. The Air Force Research Laboratory Space Vehicle Technologies Division, in conjunction with Aeronautical and Astronautical Engineering Department at Stanford University, has been doing research into a new structural configuration fabricated using the newly developed Tooling Reinforced Grid (TRIG) process. These innovative lightweight TRIG structures are extremely stiff and easy to manufacture. Additionally, TRIG structures can be several times lighter than traditional composite structures for stiffness-controlled applications. The first full-scale TRIG structure, with accompanying deployment structure/hardware, was recently fabricated as part of a precision-deployed optical boom experiment. The objective of this experiment was to study deployment accuracy and stability. In this paper, an overview of this experiment is presented from a deployment and structural point of view.