                                                                                                         2.3 Example of Using the SE Engine


2.3 Example of Using the SE Engine                                             In Pre-Phase A, the SE engine is used to develop the
                                                                               initial concepts; develop a preliminary/draft set of key
To help in understanding how the SE engine is applied,                         high-level requirements; realize these concepts through
an example will be posed and walked through the pro-                           modeling, mockups, simulation, or other means; and
cesses. Pertinent to this discussion are the phases of the                     verify and validate that these concepts and products
program and project life cycles, which will be discussed                       would be able to meet the key high-level requirements.
in greater depth in Chapter 3.0 of this document. As de-                       Note that this is not the formal verification and valida-
scribed in Chapter 3.0, NPR 7120.5 defines the life cycle                      tion program that will be performed on the final product
used for NASA programs and projects. The life-cycle                            but is a methodical runthrough ensuring that the con-
phases are described in Table 2.3‑1.                                           cepts that are being developed in this Pre-Phase A would
                                                                               be able to meet the likely requirements and expectations
Use of the different phases of a life cycle allows the var-                    of the stakeholders. Concepts would be developed to the
ious products of a project to be gradually developed and                       lowest level necessary to ensure that the concepts are fea-
matured from initial concepts through the fielding of the                      sible and to a level that will reduce the risk low enough to
product and to its final retirement. The SE engine shown                       satisfy the project. Academically, this process could pro-
in Figure 2.1‑1 is used throughout all phases.                                 ceed down to the circuit board level for every system.


                                                     Table 2.3‑1 Project Life-Cycle Phases
                     Phase                                          Purpose                                          Typical Output
                   Pre-Phase A       To produce a broad spectrum of ideas and alternatives for missions         Feasible system concepts
                   Concept           from which new programs/projects can be selected. Determine feasi-         in the form of simulations,
                   Studies           bility of desired system, develop mission concepts, draft system-level     analysis, study reports,
                                     requirements, identify potential technology needs.                         models, and mockups
                   Phase A           To determine the feasibility and desirability of a suggested new major     System concept definition



  Formulation
                   Concept and       system and establish an initial baseline compatibility with NASA’s stra-   in the form of simulations,
                   Technology        tegic plans. Develop final mission concept, system-level requirements,     analysis, engineering
                   Development       and needed system structure technology developments.                       models, and mockups and
                                                                                                                trade study definition
                   Phase B           To define the project in enough detail to establish an initial baseline    End products in the form
                   Preliminary       capable of meeting mission needs. Develop system structure end             of mockups, trade study
                   Design and        product (and enabling product) requirements and generate a prelimi-        results, specification and
                   Technology        nary design for each system structure end product.                         interface documents, and
                   Completion                                                                                   prototypes
                   Phase C         To complete the detailed design of the system (and its associated            End product detailed
                   Final Design    subsystems, including its operations systems), fabricate hardware, and       designs, end product
                   and Fabrication code software. Generate final designs for each system structure end          component fabrication,
                                   product.                                                                     and software development
                   Phase D           To assemble and integrate the products to create the system, mean-         Operations-ready system




  Implementation
                   System            while developing confidence that it will be able to meet the system        end product with sup-
                   Assembly,         requirements. Launch and prepare for operations. Perform system            porting related enabling
                   Integration and   end product implementation, assembly, integration and test, and            products
                   Test, Launch      transition to use.
                   Phase E        To conduct the mission and meet the initially identified need and             Desired system
                   Operations and maintain support for that need. Implement the mission operations
                   Sustainment    plan.
                   Phase F           To implement the systems decommissioning/disposal plan developed Product closeout
                   Closeout          in Phase E and perform analyses of the returned data and any
                                     returned samples.


                                                                                                NASA Systems Engineering Handbook  7
