Using a Thermal Infrared Imager to Evaluate Mirror Temperature During Flight for THAI-SPICE

The purpose of this investigation is to understand the thermal behavior of the primary mirror in passively-cooled, balloon-borne telescopes by means of various temperature sensors. This study is part of a larger project for developing a high-altitude balloon for diffraction-limited IR astronomy called THAI-SPICE (Testbed for High-Acuity Imaging - Stable Photometry and Image Motion Compensation Experiment). As part of this project, a quarter-scale model of the gondola launched in October of 2019 as an experimental precursor to the full-scale flight. This gondola has temperature sensors throughout the structure, as well as a thermal imaging camera looking directly at the primary mirror. This report will focus on the processing and interpretation of this data as it relates to the primary mirror, in tandem with concurrent investigations into other areas of the thermal design, to inform future flights.