SBIR-STTR Award

This NASA SBIR Phase I proposal is in response to the need for Ultra-Stable Telescope Structures at 10m to 20m length scales and is designed to scale ultra-stable ALLVAR Alloy struts from cm-length to m-length scales. Additionally, a novel method for tuning a strut’s CTE without changing the strut’s length will be validated for their potential use in space-telescope structures critical to NASA’s future missions. Telescopes used for astrophysics, exoplanet, and planetary studies require picometer stability over several minutes to hours. Building large support structures with picometer level stability is a challenge with currently available materials such as carbon fiber composites due to their high cost and moisture expansion. ALLVAR Alloys offer a new material solution for thermally stable structures. They exhibit negative thermal expansion and can compensate for the positive thermal expansion of other materials to stabilize a telescope. Bars with thermal stability approaching Zerodur’s® have previously been made by joining ALLVAR Alloys to commercially available Titanium alloys and struts exhibiting pm-level stability have been fabricated and tested. This Phase I project is designed to leverage this previous development to create the first large scale ultra-stable ALLVAR Alloy structures and develop a brand-new method for tuning its CTE. If successful, this new technology could enable CTE tuning of fully assembled ultra-stable structures in-situ. The Phase I project would fabricate and characterize a ~2m long strut segment in preparation for larger scale manufacturing and testing in a Phase II project. Potential NASA Applications (Limit 1500 characters, approximately 150 words): New large-scale materials with picometer stability and CTE tunability can potentially improve support structures for optic systems critical to NASA’s Science Mission Directorate including LUVIOR, OST, and HabEx. ALLVAR Alloys are a truly cross-cutting technology that can impact ultra-stable coronograph hardware, support structures for deformable mirrors, telescope steering, and star trackers, and other applications in NASA’s Science Mission, Space Technology, and Aeronautics Mission Directorates. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): ALLVAR Alloy’s unique negative thermal expansion properties can compensate for thermal focus shift in refractive infrared optics allowing infrared optics manufacturers to reduce the size and weight of their optics. Negative thermal expansion washers and spacers can also enable constant force fasteners that do not loosen under repeated thermal cycles. Duration: 6

ALLVAR Alloys-30 shrinks when heated and expands when cooled, known as negative thermal expansion (NTE). This opposite effect from most materials allows Alloy-30 to compensate for positive thermal expansion (PTE) materials. We have created a new material for athermalizing optics made from any type of mirror material by joining Alloy-30 to other PTE metals to create a specified thermal expansion coefficient. Currently, achievable coefficients of thermal expansion (CTE) range between -30 ppm/K, Alloy-30’s CTE, to +24 ppm/K, Aluminum’s CTE. This provides a new alternative material to currently used carbon fiber composite metering structures and trusses used in optics. The pm-stability of these new metal structures have already been achieved. If this new technology can be scaled to have ultra-stability at meter length scales and the CTE tuned to within ppb/K, they could be used as metering structures in EUV/Optical/IR large area telescopes. The novel CTE tuning method has the potential to simplify the manufacturing and alignment and offer greater thermal stability of these optic systems. Potential NASA Applications (Limit 1500 characters, approximately 150 words): New large-scale materials with picometer stability and CTE tunability can potentially improve support structures for optic systems critical to NASA’s Science Mission Directorate including LUVIOR, OST, and HabEx. ALLVAR Alloys are a truly cross-cutting technology that can impact ultra-stable coronograph hardware, support structures for deformable mirrors, telescope steering, and star trackers, and other applications in NASA’s Science Mission, Space Technology, and Aeronautics Mission Directorates. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): ALLVAR Alloy’s unique negative thermal expansion properties can compensate for thermal focus shift in refractive infrared optics allowing infrared and visible refractive optics manufacturers to reduce the size and weight of their optics. Negative thermal expansion washers and spacers can also enable constant force fasteners that do not loosen under repeated thermal cycles. Duration: 24