Characterization and calibration of VIS cameras for space applications - JANUS and HYPSOS systems

Optical instruments are fundamental tools of the space missions for Solar System exploration. They can differ both for the observed region of electromagnetic spectrum and for the type of instrument. However, they all have a common denominator: must be calibrated and characterized. Instruments on board space missions operate in harsh environments and suffer from thermomechanical stresses, but they must guarantee their capabilities. The calibration process allows to have a mapping between the external ambient and the data generated by the instrument observing it, providing information in physical units. The characterization process allows to have an understanding of how the single components work and of the whole system, improving the comprehension of the instrument itself. A well characterized and calibrated instrument will provide more reliable data, its behaviour will be more predictable and it allows to identify possible problems during its operative lifetime. This thesis applies this theme to different types of instrument, and in different development phase: JANUS (Jovis Amorum ac Natorum Undique Scrutator), a high-resolution camera ready to be launched towards the Jovian system in April 2023 on board the ESA JUICE (JUpiter ICy moons Explorer), and HYPSOS (HYPerspectral Stereo Observing System), a stereo imaging spectrometer which has been realized in laboratory as a prototype with the goal to validate a new concept of instrument. The first part of the thesis is dedicated to the activities conducted on JANUS, in particular about the analysis of the on ground calibrations data. In Chapter 1 the JUICE mission, JANUS, its scientific objectives and technical solutions are described. It provides the context for the Chapter 2 and 3. In Chapter 2 the methodologies applied for the analysis of the calibrationd data, discussion and results for radiometric, spectral and geometrical calibrations are presented. There is also an analysis of the detector performances (such as, offset stability, dark current, readout noise) and of an unexpected effect observed directly on the data. Chapter 3 shows an analysis performed to identify scientifical interesting targets (Targets of Opportunity) potentially observable by JUICE (and in particular JANUS during the long interplanetary cruise toward the Jovian System. The remaining Chapters describe the activities performed at CNR-IFN in Padua, to develop, to characterize and to integrate HYPSOS and the setup in the optical bench. Chapter 4 describes the experiment, the instrument design and its working principle. Moreover, it provides the context for the following Chapters (5,6,7). Chapter 5 is dedicated to the characterization activities performed on the two aspheric off-axis mirrros composing the HYPSOS' telescope, and on the selected diffraction grating. Chapter 6 describes the adopted solutions on the optical bench for the experimental setup both in terms of optomechanical and control software. Finally, Chapter 7 describes the characterization activities on the spectrometer (including a preliminar spectral calibration) and the methodologies used for the alignment of both the diffraction grating on the spectrometer and Three Mirror Anastigmat telescope of the instrument.