REQUIREMENT DEVELOPMENT OVERVIEW Ellen R. Taylor Mission Systems Engineer Space Science Laboratory

1. REQUIREMENT DEVELOPMENT OVERVIEW Ellen R. Taylor Mission Systems Engineer Space Science Laboratory University of California - Berkeley

2. Requirement Overview • Requirement Process • Requirement Development and Verification Plan • Requirement Flow-down • Requirement Documentation • Mission Requirements Database (MRD) Description • Requirements Document Tree • Key Requirement and Interface Documents • Requirement Control • Resources • Resource Allocation • Resource Tracking and Control

3. Requirement Development • Top-Level requirements developed during Phase A • Concept Study Report provides basic mission concept • Outlines top-level requirements imposed by science and programmatic objectives • Mission requirements flown down (to subsystem level), formalized and documented early in Phase B • All elements of the THEMIS CSR concept and mission requirements reviewed by development team • Instrument Internal Review - May 25, 26 • Probe and Probe Carrier Internal Review - May 26 • Ground System Requirements Review - June 2 • Science Requirements Review - June 3,4 • Mission Requirements Database (MRD) developed and reviewed • Probe and Probe Carrier MRD Review - June 17 • Mission MRD Review - June 24, 25 • Finalize Mission Requirements Database and put under Configuration Control • System Requirements Review (SRR) - July 8, 9 • Ensures requirements are well understood down to subsystem level, attainable and sufficient to meet mission objectives prior to detailed preliminary design

4. Requirement Development & Verification • Subsystem Interfaces and Component Requirements further detailed in Phase B • Interface Control Documents between Subsystems and Institutions • System and Subsystem Specifications (Electrical Spec, SOWs, etc) • Mission Plans and Policies (Safety Plan, Risk Mitigation Plan, etc) • Control Plans (Magnetics, Electrostatic Cleanliness, Contamination) • Requirement Verification Plans developed in Phase B and C • Mission Requirements Document evolves into a Verification Matrix ensuring test or analysis is scheduled for all Mission Requirements in MRD • Performance Verification Plan and Environmental Test Specification provides launch and space environments and outlines comprehensive component, subsystem and system level test program • Requirements Compliance and Verification Matrices completed in Phase D • Mission Requirements Document evolves into summary of test program as run • Documents Verification and Compliance Status of all Requirements • Provides direct traceability from requirements to test procedures and reports

5. WBS 1 WBS 1.1 WBS 1.2 WBS 1.3 Requirement Flow-down • Budget • Schedule • R&QA • Mission Phases • States and Modes Rules/ Regulations • Contract Deliverables • Reviews Programmatic Constraints Science Goals/ Objectives • Level 1 Science Operations Concept Level 1 (Drivers) WBS 1.1 - Management WBS 1.2 - Science WBS 1.3 - Systems Engineering Mission Requirements Level 2 (System/ Segment) WBS 2 WBS 2 WBS 3,4,5 • Mission Design (Lifetime, orbits, etc) • Fault Tolerance, Redundancy • Environment (radiation, thermal, etc) • Resource Budgets • Contamination • Interface Requirements • Environment (vibration, etc) • Constraints (mass, shroud, etc) • Test Requirements • Launch Site requirements • Safety Space System Requirements Launch Vehicle Requirements Ground System Requirements WBS 2 - Space Segment WBS 3 - Ground Segment WBS 4 - Operations Preparations WBS 5 - Mission Ops/Data Analysis WBS 2.1 WBS 2.2.2 WBS 2.2.4 WBS 3.3 WBS 3.1, 3.2 Instrument Requirements Probe Bus Requirements Probe Carrier Requirements GBO Requirements Operation/ Ground Station Requirements Level 3 (Element) WBS 2.1 - Instrumentation WBS 2.2 - Spacecraft WBS 3.1 - Mission Operations WBS 3.2 - Science Operations WBS 3.3 - Ground Based Ops • Mission Flow-down • Instrument Derived Level 4 (Subsystem) Gnd Sta. Req. MOC Req. FGM Req. ESA Req. SST Req. C&DH Req. Mech. Req. Thermal Req. ACS Req. Comm. Req. Mech. Req. Thm. Req. GMAG Req. ASI Req. SOC Req. OPS Req. SCM Req. EFI Req. IDPU Req. Power Req. Software Req. RCS. Req. Harness Req. Harness Req. ACS. Req. Site Req. Obs. Req. Instrument Performance Requirements derived directly from Level 1 Science Requirements Component Level Assembly Level All lower levels are the responsibility of the Subsystem Leads Subassembly Level Part Level

6. Database Description • Requirement Categories tracked explicitly in Database • Functional/Performance Requirements (Science, Mission Design and Operations based) • Resource Requirements (Mass, Power, Data Allocations, etc.) • Interface Requirements (Timing, Power Distribution, etc.) • Environmental Requirements (Thermal, Radiation, Contamination, etc.) • Requirement Categories tracked by Program Management • Cost • Schedule • Personnel • Facilities • Database Tool • Excel Spreadsheet Tool, developed by Swales • Each requirement has a separate row with Unique ID • Provides direct trace-ability with use of Parent, Child IDs for each requirement

7. Database Attributes

8. Requirements Document Tree MIDEX Announcement of Opportunity AO Proposal Phase A Concept Study Report (CSR) • Contract NASA/UCB • SOWs, T&Cs, CDRLs • Contract UCB/Swales • SOWs, T&Cs, CDRLs Program Assurance Requirements GSFC-410-MIDEX-002 • Master Schedule • WBS & WBS Dictionary • Org Chart & Staffing • Program CM Plan • Risk Mgmt Plan • Safety Plan - MSPSP • Reporting Requirements Program-Level Req. for the THEMIS Project (Level 1 Science) Mission Requirements Database (MRD) Performance Assurance and Implementation Plan (PAIP) THEMIS Program Plans Quality System based on ANSI/ASQ Q9001-1994 Ground System Document Tree Verification Plan and Environmental Specification Workmanship Standards NASA-STD-8739 Instrument Document Tree Probe / Probe Carrier Document Tree Safety EWR-127-1 Electrical System Specification • Subsystem Specifications • Design Documents • Schematics • Material and Parts Lists • Mechanical Drawings • Assembly Drawings • Procured Component SOWs • Acceptance Data Packages • Software Development Plans • Integration and Test Plans • Subsystem Test Plans • Test Procedures Instructions for EEE Parts Selection GSFC 311-INST-001 Contamination Control Plans (MAG/ESC/Cont) GEVS-SE (as applicable) Interface Control Documents (ICDs) ELV System Safety Milestone & Process Flow NASA-STD-8719.8 June 1998 NASA Controlled Documents

9. Key Requirement Documents • Interface Control Plans: Sign-off by PDR • Instruments-to-IDPU ICDs (covers software, data, electrical) • Instruments-to-Probe ICDs (covers mechanical, thermal, contamination) • Probe-to-IDPU ICD (electrical and mechanical) • Probe-to-Probe Carrier ICD • Launch Vehicle ICD (Boeing Mission Specification) • Ground System ICDs (Space-to-Ground link, Ground Station, Data System) • Electrical System Specification: Sign-off by PDR • Provides Electrical Standards for board design • System Plans for grounding, EMI, EMC, etc. • Contamination Control Plans: Draft by PDR, Sign-off by CDR • Separate Plans for Magnetics, Electrostatic Cleanliness (ESC) and Molecular Contamination • Provides contamination budgets, best design practice guidelines and verification plans • Verification Plan and Environmental Specification: Draft by PDR, Sign-off by CDR • Performance Verification Plan • Qualification Philosophy and Test Levels (Acceptance, Qualification, Protoflight) • Vibration/Loads/Shock Environments • Thermal Vacuum/Balance Environments • EMI/EMC/Magnetics/ESC Test Requirements • Mission Simulations and RF Compatibility Testing

10. Requirement Control • Mission Requirements Document placed under configuration control after SRR • Sign-off MRD following recommendations from the SRR review team • MRD under revision control until PDR, ownership resides with MSE • Changes to MRD after PDR will require formal notice - Engineering Change Order (ECO) • Requirements Control/Concurrence implemented throughout project • All changes to controlled documents require concurrence by appropriate team members • Subsystem trades (level 4) can be made within the resources of the subsystem. Systems Engineer insight and involvement. • Trades that impact subsystem/system interfaces or resource allocations (level 3/level 2) require concurrence by the Configuration Control Board (CCB): Principal Investigator, Project Manager, Mission Systems Engineer (MSE), Probe Systems Engineer, Mission Operations Manager and affected Team Leads. GSFC Mission Manager insight. • Trades that impact Level 1 baseline science/programmatic requirements must include approval by Principal Investigator and GSFC Mission Manager. • Trades that impact Level 1 minimum science/programmatic requirements must include approval by NASA HQ. • Document Revision and Signature Pages (with initial approval for each revision) maintains history and protects against uncoordinated/unauthorized change

11. Resource Tracking and Control • In order to ensure that the design will meet Mission Requirements, Systems Engineering controls the following key resources: • Mass (dry mass, delta-V, propellant margin) • Power • Telemetry (data budget) • RF Link Margin • Resource Requirements have been flowed down to the Probe, Probe Carrier, and Instrument Payload in the MRD • Each Instrument and Probe Subsystem includes: • Current Best Estimate (CBE), updated periodically as the design matures • Contingency, based on design maturity Concept 25%, Design 15%, Prior Build 7.5%, Fabrication 4%, Flight 2% • System not-to-exceed allocation (current CBE + contingency) documented in Mission Requirements Database • Sum of not-to-exceeds is less than the System Capability providing Program Managers Margin held at UCB • All Resources closely tracked throughout program • Continually tracked and updated by System Engineers (Probe and Instrument) • Periodically (once a month) reported to and reviewed by MSE and PM • Periodically (once a month) reported to NASA Mission Manager