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Structural-Thermal- Optical-Performance (STOP) analysis for the prediction of the line of sight stability of JANUS camera on board JUICE ESA mission
JANUS (Jupiter Amorum ac Natorum Undique Scrutator) is a high-resolution camera to be flown on board JUICE Spacecraft, devoted to investigate the atmosphere of Jupiter and the surfaces of his icy moons (Europa, Ganymede and Callisto), in the frame of ESA “Cosmic Vision” program. The scientific objectives that JANUS will reach constrained the design of JANUS Optical Head Unit (OHU), and in particularthe specific measurement of Ganymede Libration, imposes highly stringent requirement on the Line of Sight (LoS) knowledge of the instrument. The differential thermal environment conditions of the mission orbits, as well as the instrument heat dissipation timelines, induce optical components translation and rotations that correspond to a Line of Sight variation. During the mission, the LoS can be characterized with a stellar field or single star observation but none direct measurement of its variation can be retrieved during the scientific imaging sessions. To recover the LoS knowledge, a Structural Thermal Optical and Performance Analysis (STOP) is implemented. The optics and the instrument structure are FE modeled and processed (NASTRAN) imposing the temperature distributions obtained by the OHU Thermal Model (ESATAN-TMS). The obtained Thermo-elastic deformations are then considered in the OHU Optical Model (ZEMAX). The resulting LoS and the dominant OHU temperature gradients are finally entangled with a proportionality relation, as well as its direction uncertainty. The indirect estimation of the LoS variation, and its uncertainty, can be establish, thanks to STOP analysis, in real time during operations as function of installed temperature sensor measurements.
Turella Andrea, Della Corte Vincenzo, Paolinetti Riccardo, Palumbo Pasquale, Amoroso Marilena, Castronuovo Marco, Mugnuolo Raffaele
Paper for Seminar/Symposium/Conference
SPIE - Optical Engineering + Applications Conference (11-15 August 2019, San Diego, CA , USA)
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