This thesis describes part of the activities carried out within phase A of MiniCOR (Mini CORonagrpah) mission at the Turin headquarters of Argotec S.r.l. as an intern in system engineering. MiniCOR is a 6U LEO spacecraft for observing the kinematics of CME and studying the Sun-Earth interaction. The mission is also seeing the cooperation of the Naval Research Laboratory (NRL) and the Applied Research Laboratory (APL) Johns Hopkins Institute that will provide the scientific payload. The activities included: •??Mission Objectives definition; •??Functional Analysis; •??Mission Architecture description; •??Concept of Operations; •??Definition of mission and preliminary system requirements derived from mission objectives; •??Definition of a preliminary system architecture and configuration; •??System budgets; •??Preliminary Failure Mode and Effects Analysis (FMEA).