Which SE Technical Process focuses on defining the design of the system?

The process that focuses on defining the design of the system is Design Definition. This phase is critical as it involves creating a detailed blueprint of the system, including specifications, interfaces, and components that fulfill the requirements established in earlier phases of the systems engineering process.

During the Design Definition process, systems engineers work to elaborate on the system architecture, ensuring that both the functional and non-functional requirements are met. It encompasses various activities, such as creating models, prototypes, and detailed design documents, which guide the implementation of the system.

In contrast, other options like Architecture Definition primarily focus on establishing the high-level framework of the system and how its components will interrelate rather than the detailed design aspects. Business/Mission Analysis is centered on understanding and defining the needs and goals of the stakeholders rather than the design. Disposal pertains to the end-of-life phase for a system, dealing with the decommissioning and recycling, which is unrelated to design activities. Thus, Design Definition is distinctly focused on creating the comprehensive design necessary for the system's realization.