Description: After optical performance, the most important metric for advanced optical systems is the areal cost (cost per square meter of collecting aperture). Future NASA space mirror requirements call for an order of magnitude improvement in areal cost over current technologies. With this goal in mind, Semplastics will leverage existing in-house technologies to develop an ultra-low cost, lightweight, molded, chalcogenide glass-silicon oxycarbide (SiOC) composite mirror component. This novel silicon oxycarbide substrate has the advantage of using an extremely low-energy process to produce a molded bulk ceramic substrate with weight-reducing rib patterns on the back of the substrate. This silicon oxycarbide ceramic is much lighter in weight than bulk ceramics like silicon carbide or lithium aluminosilicate glass ceramics such as ZerodurTM, resulting in an additional benefit in the potential for reduction of on-orbit mass for space missions using this technology. Chalcogenide (ChG) Glass is used to fill in the pores of the porous bulk and support transitioning to a smooth, thermally matched surface ready for aluminization for mirror formation. Successful completion of this development effort will meet both the cost and optical performance targets for next-generation Ultraviolet/Optical and Infared mirror components.

Benefits: Several NASA activities benefit from improvements in mirror performance as well as a significant reduction in areal costs. Earth-observing and space-observing telescopes that are either balloon-borne or on-orbit have a constant need to reduce the cost and mass of their optical systems. In NASA's search for extraterrestrial life, the mission is to locate stars with planets similar to Earth. Mirror technology is a significant key in determining whether an exoplanet's atmosphere has atmospheric water vapor or carbon dioxide as well as measuring other atmospheric chemicals. Other NASA programs with interest in improved mirror technology include the Climate Absolute Radiance and Refractory Observatory (CLARREO) and the European Space Agency (ESA)/NASA dark-energy mission Euclid. The CLARREO effort is a future Earth-observing mission that will establish climate benchmarks in order to assess optimizing strategies for mitigating and adapting to climate change. The Euclid space observing mission will address questions related to the fundamental physics and cosmology on the nature and properties of dark energy, dark matter, and gravity. Reduced areal costs translate directly to cost savings on these projects, increasing chances of success.

Commercial applications for this technology outside of NASA are numerous. Other agencies and entities such as the Department of Defense (DoD) also make use of Earth-observing satellites. While the DoD may be less sensitive to areal cost than other agencies or the commercial sector, they are very sensitive to on-orbit mass. The need to make frequent adjustments to satellite orbits requires a large amount of fuel; by reducing the mass and moment of inertia of the optical system, this technology will enable mission extension through onboard fuel savings. Further commercial potential is identified in the planned large-aperture, multi-segmented, ground-based observatories. The 39-meter European Extremely Large Telescope (E-ELT) and the 74-meter Colossus telescope are examples of these upcoming projects. Enormous optical components will be acquired for these instruments; for example, the E-ELT has been designed with an array of 798 hexagonal 1.4-meter wide main mirror segments, as well as three large downstream mirrors, and the mirror material has yet to be selected. Because the technology being developed in this Phase I effort uses a molding technique, mirror segments can have a light weighting rib pattern easily created for each mirror. This feature, along with the inherent low density of the ceramic material, leads to a major weight savings which propagates through the entire telescope support/pointing system, representing potential cost savings in the billions of dollars.