EnMap In-flight Calibration Status

Abstract

The Environmental Mapping and Analysis Program (EnMAP) hyperspectral satellite mission was successfully launched on 1st April 2022. The mission aims to monitor and characterise Earth’s environment in the spectral range from 420 - 2450 nm. The VNIR sensor provides 91 science channels ranging from 420 - 1000 nm with an average Spectral Sampling Distance (SSD) of 6.5 nm. While the SWIR sensor covers the range from 900 - 2450 nm with 131 channels and 10nm SSD. - The off-nadir pointing capability (up to 30 degrees) enables 5000 km to be monitored per day, with a swath width of 30 km and a spatial resolution of 30 m. The EnMAP satellite is equipped with several subsystems which allow periodic in-flight monitoring and calibration. The Full Aperture solar Diffuser Assembly (FADA) is used for absolute radiometric calibration. The On-Board Calibration Assembly (OBCA) is composed of 2 integrating spheres: one is coated with a doped diffuser material and is used for the spectral calibration; the second sphere, coated with a white spectralon, is used for Radiometric stability monitoring. Linearity LEDs are placed in front of the detector to monitor their linearity by measuring the response at constant illumination with increasing integration times. The Shutter Calibration Mechanism (SCM) allows for measurements with no light input to be performed in order to compute Dark Signal values and, in combination with Deep Space measurements, to compute any existing shutter emission in the SWIR range. This contribution will present a summary of the calibration activities performed during the EnMAP Commissioning Phase.