Attachment D
Systems Integration Tasks
The Office of Exploration Systems has defined Project Constellation in terms of six tiers:
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Tier 1. Enterprise Elements: Project Constellation (a system of systems)
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Tier 2. System (e.g., crew transport system, surface systems)
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Tier 3. Segment (e.g., crew exploration vehicle, launch vehicle, ground segment)
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Tier 4. Element (e.g., booster element)
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Tier 5. Subsystem (e.g., booster main engine)
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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:
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refinement of Tier 1 performance requirements
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drafting of verification and validation requirements and plans for Tier 1 requirements
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completion of system-of-systems architectural trade studies leading to refined Tier 1 (system of systems) architectures and concepts of operation, including—
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top-level operational sequences of operations
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operational block diagrams (for each operational phase)
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system-of-systems block diagrams (for each operational phase)
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information architecture
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definition of other top-level requirements across a system of systems, such as redundancy, reliability, and availability
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flowdown of system of systems performance requirements to Tier 2 systems—
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crew transport
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cargo transport
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surface systems
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in-space systems
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ground systems
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robotic precursors
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development of functional interface specifications for Tier 2 systems
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drafting of verification and validation requirements and approaches for Tier 2 systems
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refinement of program approach and phasing at the Tier 1 level
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establishment, operation, and support of other critical systems integration functions, such as:
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configuration management and control (including Tier 1 Change Control Board)
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mission assurance and safety including Tier 1 failure mode and effects analysis (FMEA)
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Tier 1 risk analysis and risk reduction programs
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maintenance and rebalancing of the efforts listed above as required
Completing these tasks will require at least the following inputs:
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Project Constellation vision
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Project Constellation top-level requirements (system of systems)
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preliminary system-of-systems architectures developed by NASA
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preliminary program approach and phasing developed by NASA
TIER 2: SYSTEMS
At Tier 2, the systems integrator would accomplish tasks such as the following:
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refinement of Tier 2 performance requirements
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drafting of verification and validation requirements and plans for Tier 2 requirements
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completion of architectural trade studies leading to refined architectures for each Tier 2 system (Tier 2 expansions of Tier 1 architectural products)
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definition of other Tier 2 level requirements, such as redundancy, reliability, and availability
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flowdown of Tier 2 performance requirements to Tier 3 (Segment), such as the following in the crew transport system:
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crew exploration vehicle
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launch vehicle
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extravehicular activity systems
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intravehicular activity systems
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in-space transport systems
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development of interface specifications for Tier 3 systems
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drafting of verification and validation requirements and plans for Tier 3 requirements
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refinement of program approach and phasing for Tier 2
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establishment, operation, and support of other critical systems-integration functions, such as:
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configuration management and control (including Tier 2 Change Control Board)
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mission assurance and safety, including Tier 2 FMEA
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Tier 2 risk analysis and risk reduction programs
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maintenance and rebalancing of the efforts listed above as required
Completing these tasks will require at least the following inputs:
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Tier 1 outputs
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Tier 2 program constraints from NASA