Monitoring the performances of MAJIS from ground to flight calibration measurements

Abstract

  ESA’s Jupiter Icy Moons Explorer (JUICE) mission scientific payload includes a 2-channels (visible to near-infrared (VISNIR) and infrared (IR)) cryogenic imaging spectrometer instrument called the Moons And Jupiter Imaging Spectrometer (MAJIS). During its ground calibration campaign, this instrument was tested at different operative temperatures, and calibration measurements were acquired to derive the spatial, spectral, and radiometric performances. Following the launch of the JUICE mission to the Jovian System, the first in-flight measurements were acquired during the near-Earth commissioning phase (NECP). In flight, the internal calibration unit (ICU) was used to monitor the instrument’s response.  In particular, the ICU signal provides full illumination of the instrument's field of view. It exhibits several absorption bands thanks to a didymium and a polystyrene filter placed in front of the VISNIR and IR sources, respectively. The performances of the instrument are evaluated through several metrics, including the absolute spectral calibration, the full width at half maximum of the response (spatial and spectral), the distortions (keystone and smile), and the impact of the optical head temperature. The flight acquisitions will be presented and compared to the ground calibration analyses, and the current performances of the instrument will be discussed in the context of MAJIS main scientific goals.