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OCR for page 30
Systems Integration for Project Constellation: Letter Report Attachment D Systems Integration Tasks The Office of Exploration Systems has defined Project Constellation in terms of six tiers: Tier 1. Enterprise Elements: Project Constellation (a system of systems) Tier 2. System (e.g., crew transport system, surface systems) Tier 3. Segment (e.g., crew exploration vehicle, launch vehicle, ground segment) Tier 4. Element (e.g., booster element) Tier 5. Subsystem (e.g., booster main engine) Tier 6. Assembly (e.g., thrust chamber assembly) Listed below are the types of tasks that the committee believes should be included in systems integration at Tiers 1 and 2. TIER 1: ENTERPRISE ELEMENTS / SYSTEM OF SYSTEMS At Tier 1, the systems integrator would accomplish tasks such as the following: refinement of Tier 1 performance requirements drafting of verification and validation requirements and plans for Tier 1 requirements completion of system-of-systems architectural trade studies leading to refined Tier 1 (system of systems) architectures and concepts of operation, including— top-level operational sequences of operations operational block diagrams (for each operational phase) system-of-systems block diagrams (for each operational phase) information architecture definition of other top-level requirements across a system of systems, such as redundancy, reliability, and availability flowdown of system of systems performance requirements to Tier 2 systems— crew transport cargo transport surface systems in-space systems ground systems robotic precursors development of functional interface specifications for Tier 2 systems drafting of verification and validation requirements and approaches for Tier 2 systems refinement of program approach and phasing at the Tier 1 level establishment, operation, and support of other critical systems integration functions, such as:

OCR for page 30
Systems Integration for Project Constellation: Letter Report configuration management and control (including Tier 1 Change Control Board) mission assurance and safety including Tier 1 failure mode and effects analysis (FMEA) Tier 1 risk analysis and risk reduction programs maintenance and rebalancing of the efforts listed above as required Completing these tasks will require at least the following inputs: Project Constellation vision Project Constellation top-level requirements (system of systems) preliminary system-of-systems architectures developed by NASA preliminary program approach and phasing developed by NASA TIER 2: SYSTEMS At Tier 2, the systems integrator would accomplish tasks such as the following: refinement of Tier 2 performance requirements drafting of verification and validation requirements and plans for Tier 2 requirements completion of architectural trade studies leading to refined architectures for each Tier 2 system (Tier 2 expansions of Tier 1 architectural products) definition of other Tier 2 level requirements, such as redundancy, reliability, and availability flowdown of Tier 2 performance requirements to Tier 3 (Segment), such as the following in the crew transport system: crew exploration vehicle launch vehicle extravehicular activity systems intravehicular activity systems in-space transport systems development of interface specifications for Tier 3 systems drafting of verification and validation requirements and plans for Tier 3 requirements refinement of program approach and phasing for Tier 2 establishment, operation, and support of other critical systems-integration functions, such as: configuration management and control (including Tier 2 Change Control Board) mission assurance and safety, including Tier 2 FMEA Tier 2 risk analysis and risk reduction programs maintenance and rebalancing of the efforts listed above as required Completing these tasks will require at least the following inputs: Tier 1 outputs Tier 2 program constraints from NASA