The Object Of This Contract Is The Design, Implementation, Test And Validation Of The Optical Subsystem Of The Photsat Satellite, An Astrophysics Satellite Dedicated To The Observation And Monitoring Of The Brightest Stars. The Contract Includes The Following R&D Tasks: ● Design, Implementation, Test And Validation Of The Optical Subsystem Of The Photsat Satellite And Its Interfaces With The Rest Of The Astronomy Payload And The Systems And Modules Of The Platform , Based On The Requirements Described In The Technical Specifications Of The Tender. ● Support Service In The Process Of Integration, Verification And Functional Validation Of The Photsat Astronomy Payload (Ait/Aiv Of The Payload). ● Technical Support Service During The Satellite'S Aiv/Ait Campaign. The Intention Is To Hire An Innovative Solution, Which Does Not Exist On The Market, Which Can Solve The Optical Subsystem For The Photsat Satellite According To The Needs Detected By The Ieec.