Project phases — ESA project

ESA practiceFig. 1. : Typical ESA phasing of a space experiment. The different phases are separated each by formal reviews; phase A corresponds to an already accepted proposal and at its end, at the PRR, preliminary requirements review, one can consider that the feasibility is accepted from an engineering point of view. A project can be modified in phase A by elements which were not known at proposal level as the budget envelope or the constraints of the launcher. Phases C and D are especially important because irreversible decisions are taken in terms of instrument integration as actual hardware is manufactured. Phase E is the flight phase while phase F as the disposal phase corresponds to archiving and review. A project like PERICLES intends to structure this final phase.