Pre-launch Calibration of the NASA TROPICS Constellation Mission

The NASA TROPICS mission [1] hosts a high performance radiometer to estimate temperature and water vapor profiles, precipitation, and Tropical Cyclone intensity. Noise Diodes (ND) are an attractive option for calibration of small satellite sounders, especially in the face of volume constraints that preclude extensive radiative shielding of internal calibration targets that is utilized in operational missions [2]. Recent operational missions [3], [4] demonstrated on-orbit ND calibration stability better than 0.1 K over more than four years when prelaunch screening of the ND is used. An essential step for TROPICS is the precise prelaunch characterization of the ND performance over a variety of thermal conditions, which will be augmented by post-launch cross-comparisons similar to the techniques used by the GPM Intercalibration (X-CAL) Working Group. This paper introduces the first radiometric calibration characterization and verification with the radiometer integrated on the satellite platform under flight-like conditions.