FLEX low resolution spectrometer breadboard activities

The FLEX Space Segment consists of a single satellite carrying the FLuORescence Imaging Spectrometer (FLORIS) operating in the 500-780 nm spectral band [1]. FLEX will fly in tandem with Copernicus Sentinel-3 working in combination with the Ocean and Land Color Instrument (OLCI) [2] and the Sea and Land Surface Temperature Radiometer (SLSTR) [3,4]. FLEX will provide important additional information regarding the vegetation fluorescence signal and a more accurate atmospheric corrections, which are essential for a quantitative evaluation of the status of health of vegetation. The FLORIS instrument [5] is composed of a High (HRS) and a Low Resolution Spectrometer (LRS), with a spectral sampling and resolution respectively of 0.1 and 0.3 nm (HRS), and 0.6 and 1.8 nm (LRS). A flight representative breadboard of the High Resolution Spectrometer was developed by Leonardo and testing results can be found in reference [6]. OHB is responsible of the Low Resolution Spectrometer and another breadboard was designed, manufactured, integrated, aligned and tested at OHB premises. This paper presents the results of the breadboard campaign for the LRS and shows the derived Flight Model (FM) alignment strategy.