Precision Thermal Control (PTC) Technology to Enable Thermally Stable Telescopes

The Precision Thermal Control (PTC) project was a multiyear effort initiated in Fiscal Year 2017 to mature the Technology Readiness Level (TRL) of technologies required to enable ultra-thermally stable ultraviolet/ optical/infrared (UVOIR) space telescope primary-mirror (PM) assemblies for ultra-high-contrast observations of exoplanets. PTC had three objectives: (1) validate thermal optical performance models, (2) derive thermal system stability specifications, and (3) demonstrate multi-zonal active thermal control. PTC successfully achieved its objectives and matured active thermal control technology to at least TRL 5. PTC’s key accomplishments are a demonstration of better than 2-mK root-mean-square (rms) stable thermal control of the 1.5-m ultra-low-expansion (ULE®) Advanced Mirror Technology Development-2 (AMTD-2) mirror when exposed to thermal disturbances in a relevant thermal/vacuum environment, and the ability to shape the 1.5-m AMTD-2 mirror to picometer precision.