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De LISA Pathfinder aÌ LISA: EÌlaboration dâun simulateur dynamique pour la mission spatiale eLISA
The gravitational Universe and the rise of an entirely new astronomy using gravitational waves have been selected by ESA as the scientific theme for the future large space mission L3 planned for 2030 decade. In that context, eLISA (evolved Laser Interferometer Space Antenna) mission seems favored, and is besides preceded by the LISA Pathfinder mission, launched on December 2nd 2015, that aims to demonstrate the technology envisaged. The scientific outcome of this mission would be very wide, concerning at the same time fundamental physics, cosmology and astrophysics.The work described in this document allows to deliver a simulator reproducing the closed-loop dynamical behavior of a three-body system : the spacecraft and the two test-masses. The simulator is based on a Space State Model of the dynamical system, of the measurement and actuation systems and includes numerous modelled imperfections such as sensor noises and stray forces applied on the test masses (the inertial references of the system), hence allowing to study the impact of these imperfections on the detector performances. In particular, this simulation tool allows to perform preliminary estimates of a fundamental quantity, the residual acceleration, that will limit the sensitivity of eLISA to low frequency gravitational waves.LâUnivers gravitationnel et lâĂ©mergence dâune nouvelle astronomie via les ondes gravitationnelles a Ă©tĂ© sĂ©lectionnĂ© par lâESA en tant que thĂšme scientifique de la future mission large L3 prĂ©vue pour l'horizon 2030. A ce titre, la mission spatiale eLISA (evolved Laser Interferometer Space Antenna) semble privilĂ©giĂ©e, et prĂ©cĂ©dĂ©e par ailleurs par une mission de dĂ©monstration technologique, LISA Pathfinder, lancĂ©e le 3 dĂ©cembre 2015. Lâimpact scientifique dâune telle mission serait ainsi multiple et concernerait Ă la fois les domaines de la physique fondamentale, de la cosmologie et de lâastrophysique.Lâobjet de ce document est lâĂ©laboration dâun simulateur reproduisant la dynamique en boucle fermĂ©e du systĂšme Satellite-Masses dâĂ©preuve. Ce simulateur se base sur un modĂšle en espace dâĂ©tats du systĂšme dynamique et des systĂšmes de mesure et dâactuation, et inclut Ă©galement plusieurs modĂšles dâimperfection du dispositif, tels que le bruit des senseurs ou les forces parasites sâappliquant sur les masses dâĂ©preuve (rĂ©fĂ©rences dâinertie du systĂšme), permettant ainsi dâĂ©tudier lâimpact de ces imperfections sur les performances du dĂ©tecteur. En particulier, cet outil de simulation donne accĂšs Ă des premiĂšres estimations dâune quantitĂ© dâintĂ©rĂȘt majeur, le bruit dâaccĂ©lĂ©ration, qui limitera la sensibilitĂ© Ă basse frĂ©quence du dĂ©tecteur aux ondes gravitationnelles