This NASA SBIR Phase II proposal is in response to the need for Ultra-Stable Telescope Structures and is designed to evaluate ALLVAR Alloys for their potential as metering and support structures for optics that are 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 due to their brittle nature in the case of Zerodur and ULE or their requirement to have tight thermal control in the case of SiC or carbon fiber composites. 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 the Phase I effort developed stabilization processes for improved dimensional stability. This Phase II project is designed to leverage the Phase I development to create an ultra-stable ALLVAR Alloy hexapod structure and compare its performance to Invar, a commonly used low CTE material. The Phase II project would run full scale pm level stability tests of both assemblies in an effort to quantify the ALLVAR Alloy’s performance as an ultra-stable strut.
A new material with picometer stability can potentially improve support structures for optic systems critical to NASA’s Science Mission Directorate, like LUVIOR, LISA, or HabEX. There are other potential opportunities in the manufacture of ultra-stable coronograph hardware, support structures for deformable mirrors, telescope steering, and star tracker markets. ALLVAR metals can also be used to make balloon telescopes for exoplanet discovery and cryogenic far infrared telescopes.
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. ALLVAR Alloy’s unique properties are also getting attention for making washers to create constant force fasteners.