Design, Implementation, and Performance of the Cryogenic System for the EXoplanetClimate Infrared TElescope (EXCITE) Balloon Payload

The EXoplanet Climate Infrared TElescope (EXCITE) instrument is a 0.5m near-infrared spectrograph that flies from a stratospheric balloon platform. EXCITE is designed to perform phase resolved spectroscopy of hot Jupiter-type exoplanets in the spectral range from 0.8 to 4 microns. This measurement requires excellent photometric stability, imposing significant constraints on allowable mechanical disturbances and component temperatures. The EXCITE science instrument features a cryogenic spectrograph cooled to ~100K, and an infrared focal plane cooled to ~50K. These components are housed within the same dewar and are cooled by a pair of linear pulse tube cryocoolers. In this work, we present the design, implementation, and in-flight performance of the EXCITE cryogenic system. Through both ground and in-flight testing, EXCITE has demonstrated that payloads flying mechanical cryocoolers and their ancillary hardware can achieve the temperature and mechanical stability required for high precision infrared science, in a compact, reliable, and technologically mature format.