Predictive Thermal Control (PTC) technology to enable thermally stable telescopes: year four status

The Predictive Thermal Control (PTC) project is 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 assemblies for ultra-high-contrast observations of exoplanets. PTC has three objectives: validate thermal optical performance models, derive thermal system stability specifications, and demonstrate predictive thermal control. PTC has successfully accomplished all of its objectives and matured the technology to at least TRL-5 via demonstration in a relevant thermal/vacuum environment with the 1.5-m ULE© AMTD-2 mirror.