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The Sentinel-2 (S-2) mission is part of the Copernicus Space Component (CSC) – the European Commission’s Earth Observation program. It is designed to provide systematic global acquisitions of land and coastal areas at high-spectral resolution and with high revisit frequency, generating products feeding a large range of operational applications in domains such as agriculture, ecosystems management, natural disaster monitoring or water quality monitoring.
The mission is currently in its operational phase with a constellation of two satellites (Sentinel-2A and Sentinel-2B) launched in 2015 and 2017 respectively, each designed for a minimum lifetime of 7.25 years with consumables sized for 12 years. In order to provide a long-term service (up to 20-year of overall mission duration), two additional satellites Sentinel-2C and Sentinel-2D were funded by the European Commission and are presently under development.
The main S-2 payload, the Multi Spectral Instrument (MSI), is a push broom instrument with 13 spectral bands covering from the visible and the near infrared (VNIR) to the short wave infrared (SWIR). Operational experience from S-2 A&B, with new applications raising up, demonstrates how crucial and valuable accurate instrument spectral characterization is becoming. In the frame of S-2 C&D development, an enhanced spectral characterization method was implemented in order to address all the pixels of the Field Of View (FOV) on all the bands of the instrument with high precision, accuracy and sampling.
This paper describes this novel approach as well as the test setup used to characterize both VNIR channels operated at ambient pressure and SWIR channels operated at low temperature in vacuum conditions. The results of the spectral response of the thirteen bands obtained during the MSI-C test campaign executed between 2019 and 2020 and their associated accuracy are presented. Finally, the impact of spectral response variation on typical targets and the added value for the users from the accurate knowledge of the spectral response is addressed.
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