Within the framework of the overall engineering standards for space missions, this Standard contains the basic rules, principles and requirements applied to the engineering of the ground segment and mission operations, which form an integral part of the overall system implementing a space project. This Standard also addresses the relationships between a customer and the ground segment supplier (GSS) and a customer and the operations supplier (OS). The following topics are not considered: • Ground systems (e.g. EGSE) and operations to support space segment verification which are covered within ECSS?E ?ST?10?02. • The launch segment and its operations. This Standard has the following structure: • definition of the ground segment and operations domain; • requirements on ground segment engineering, i.e. the tasks required to design, implement and maintain a ground segment; • requirements on operations engineering, i.e. the tasks required to prepare and carry out operations of a space project; • identification of the relationships between the ground segment engineering and operations engineering processes and the space project lifecycle as defined in ECSS?M?ST?10. This Standard may be tailored for the specific characteristics and constraints of a space project in conformance with ECSS?S?ST?00.