Solar Irradiance Sensor of RDM Exomars 2022 calibration

Abstract

This work presents the procedure and results of the optical calibration of the SIS'22 Solar_Irradiance_Sensor (SIS'22) of METEO, the meteorological stations for the Exomars 2022 Kazachok lander. The calibration procedure applied for this multichannel radiometer is an update of the ones carried out on the DREAM-SIS for the Schiaparelli [11]lander in ExoMars '16 and RDS (Radiation_and_Dust_Sensor) for the NASA/JPL Perseverance rover [7], both sensors designed and calibrated by INTA. The main innovation introduced since the DREAMS SIS is the inclusion of some corrections in the models to improve the uncertainties and improve the detectivity limit in low light conditions. Some of the changes introduced are also related to the new challenges that this instrument faced compared to the DREAMS SIS, which had an important impact on the calibration of the mean throughput and the angular dependence (ARF): Narrower FoVs, the necessity of a new characterization of the ARF and its "blocking zone", the use of UV channels, some channels were designed to measure diffuse light in spite of direct sun light, improvement of the offset characterization and a new spectral correction in order to reduce uncertainties.