Absolute Radiometric Calibration and Uncertainty Validation for a Cubesat Thermal Infrared Radiometric Imager in Low Earth Orbit

An enabling factor for a number of proposed satellite constellation missions is an instrument design that achieves high performance, but is also simple and inexpensive to produce in multiple units. The CIRiS (Compact Infrared Radiometer in Space) mission has demonstrated a thermal infrared imaging radiometer intended to achieve this combination, with particular attention to high radiometric calibration performance. Ground and on-orbit tests measured all major instrument radiometric uncertainty components and their dependencies, in support of calibration optimization. Contributing to high calibration accuracy is CIRiS’ on-board calibration subsystem employing flat-panel carbon nanotube sources. Instrument operation prior to launch and on-orbit provided validation of radiometric uncertainty values for a comprehensive radiometric model for CIRiS and similar instruments types. The model addresses a range of science scenes and operating conditions, and has been demonstrated with images acquired during the mission.