NASA Systems Engineering Process for Programs and Projects

The NASA Program/Project Life Cycle Model is an idealized model for the complete technical life cycle of a NASA mission from initial mission conception through mission operations to final system disposal. The model partitions the life cycle into ten stages based on the objectives of the technical activity and the level of maturity of the System under development. Successive stages mark increasing system definition and maturity. A transition to a new stage entails a major shift in the nature or extent of technical activities. Control gates assess the propriety of progressing from one stage to another.

Table 3.2-1 gives an overview of the model. For each stage, the table identifies the objectives of the stage and its major technical products. The life cycle tailors the basic steps of identify, analyze, design, construct, operate, support, and dispose to NASA Missions. It must be stressed that the Program/Project life cycle model is not an actual process but rather an idealization that captures the basic logic and flow of information and products. In practice the stages are unlikely to be strictly sequential. Unfolding events may invalidate or modify goals or assumptions. This may necessitate revisiting or modifying the results of a previous stage. The entities comprising the System often have different development schedules and constraints. This is especially evident with the Final Design and Fabrication and Integration stages where some items or subsystems may be under development while others may be in construction or test.