The Asteroid Impact Deflection Assessment (AIDA) mission, a collaborative effort for Planetary Defense, involves the DART and Hera missions targeting the Didymos-Dimorphos binary asteroid system. Their objectives include assessing asteroid deflection, conducting close observations, and demonstrating future mission technologies. DART, launched by NASA, impacted Dimorphos in September 2022, while Hera, an ESA spacecraft, carrying Juventas and Milani CubeSats, is set to reach Didymos in December 2026 after a two-year Cruise phase. The French Space Agency (CNES) contributes to Hera mission through the CubeSats flight dynamics and mission planning operations. This paper discusses the CubeSats trajectory design, taking into account the platform and safety requirements and the mission payload needs.