This checklist provides comprehensive data and evidence required to certify software for human-rated missions.
It ensures compliance with applicable safety standards, regulatory requirements (NASA NPR 7150.2D
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, SSP 50038
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, FAA 450.141 Computing systems, NASA-STD-8739.8B
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), mission-critical functionality, and stakeholder acceptance of residual risks, demonstrating that the software is safe, reliable, and mission-ready for crewed spaceflight operations.
Excerpt Include
SITE:PAT-082 - Software Certification in Human-Rated Missions Checklist
SITE:PAT-082 - Software Certification in Human-Rated Missions Checklist
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2. Key Software Compliance Data Needs
2.1 Summary Table of Key Software Compliance Data Needs
Requirements
Access to the software requirements or software user stories, software acceptance criteria, software use cases, software functional specifications, software behaviors, software feature descriptions, or software tickets.
Access to the System/Software requirements traceability data
Access to the hazard control software requirements traceability data
Explanation on software safety constraints and assumptions
Access to the software requirements analysis results
Design
Access to the software design
Explanation on software fault containment and management approach
Access to the software design analysis results
Access to the Interface Control Documents (ICDs) for software interfaces
Access to the data dictionary data
Data demonstrating prerequisite checks for all hazardous commands
Explanation on how the software design and requirements meet the safety critical requirements
Explanation on how the safety-critical code is modifiable
Demonstrate that the applicable human factors design principles are in place in the software
Development
Access to the software operational plans or user’s manual
Explanation of the Fault Tolerance approach used in the design
Access to the source code
Approval data for all AI uses in flight software before deployment.
Demonstrate that the displayed confidence levels are correct for all critical AI decisions and predictions.
Demonstrate that the AI systems used in critical space flight software are managed with transparency to maintain safety, reliability, and accountability.
Access to the software defect reports (open/closed with severity), anomaly logs, residual risk acceptance with stakeholder sign-off
Access to all tailoring/waiver/deviation and TBR/TBD/FWD closure records.
Evidence that the approved software processes were followed during all software development activities
Evidence of closer of peer reviews/inspection findings for requirements, architecture/design, code and test artifacts review
Evidence of qualification and pedigree of reused/third‑party software
Provide an understanding of the certifications process for the software models & simulations used to qualify flight software.
Data showing the Worst‑Case Execution Time (WCET), timing analysis, and scheduling evidence, including partitioning and multicore interference analysis where relevant.
Verification & Validation
Access to the software test results
Access to the MC/DC coverage data for safety-critical components
Access to the static and dynamic analysis testing approach and results
Demonstrate the fault injection resilience under worst-case conditions
Demonstrate how the software handles spurious signals and invalid inputs
Provide an understanding of the certifications process for the software test environments used to qualify flight software.
Provide results of a cyclomatic complexity analyses
Provide a list of identified software issues, anomalies, and defects, with clear and traceable justifications for acceptance of any unresolved items.
Provide data showing the operational test results and data confirming system resource margins under nominal and worst-case scenarios, including CPU/memory/throughput margins data
Access to the IV&V reports and findings and an understanding of the IV&V scope
Hazard Analysis
Access to the software related hazard analysis reports, fault tree analysis, and FMEA addressing all software hazards and mitigation strategies.
Demonstrate that all AI systems generate warnings and recommendations for anomalies that could lead to hazards
Demonstrate the operator Action Validation
Explanation of the software safing Procedures
Configuration Management
Access to the software documentation,
Access to the software change Logs
Access to the software version control, baseline definitions, and audit records for all changes.
Operational Procedures
Explanation of the software control Sequences,
Explanation of any software manual safing data and processes
Cybersecurity
Demonstrate that the software has encryption, authentication, meets secure coding practices, and has access control
Access to the results showing penetration testing and vulnerability analysis
2.2 Key Software Compliance Data Needs Rationale
Section: Requirements
Item
Rationale
Access to the software requirements or software user stories, softwareacceptance criteria, softwareuse cases, softwarefunctional specifications, software behaviors, softwarefeature descriptions, or software tickets
Demonstrated the software capability definition and software testing criteria. SWEHB emphasizes complete, correct, validated SRS content as the foundation for safe, verifiable software; early clarity prevents costly downstream defects and safety gaps.
Access to the System/Software requirements traceability data
Bi‑directional traceability is required to prove every design, code, and test artifact maps to a validated system need—preventing orphan functionality and ensuring hazards are controlled.
Access to the hazard control software requirements traceability data
Hazard controls must trace explicitly from hazard analysis to software requirements and back to verification evidence to avoid missing or partial mitigations.
Explanation on software safety constraints and assumptions
Documented constraints and assumptions prevent hidden coupling and incorrect operating expectations—frequent root causes in lessons learned for hazardous behavior.
Access to the software requirements analysis results
Structured requirements analysis (ambiguity checks, safety impacts, HSI considerations) provides objective evidence that requirements are testable, feasible, and complete before design.
Section: Design
Item
Rationale
Access to the software design
Architecture/design descriptions enable validation of partitioning, redundancy, timing, and safety mechanisms; undocumented design is a recurring integration‑failure source in SWEHB.
Explanation on software fault containment and management approach
A clear FDIR strategy limits fault propagation, preserves redundancy, and supports safe recovery for safety‑critical functions.
Access to the software design analysis results
Design reviews/analyses expose interface risks, safety gaps, and performance limits early, reducing costly rework during integration/test.
Access to the Interface Control Documents (ICDs) for software interfaces
ICDs prevent interface mismatch failures—one of the most common categories of integration defects called out in SWEHB checklists.
Access to the data dictionary data
Data dictionaries provide authoritative definitions and units, preventing misinterpretation and unit conversion defects across teams/tools. (SWEHB practice captured in certification checklist.)
Data demonstrating prerequisite checks for all hazardous commands
Prerequisite checks are explicitly required for safety‑critical design to block unsafe command execution unless the system state is validated.
Explanation on how the design and requirements meet safety‑critical requirements
Explicit mapping from safety‑critical requirements to design elements verifies that every control is implemented and testable—closing common gaps seen in hazard mitigations.
Explanation on how the safety‑critical code is modifiable
Modular, isolated safety‑critical code reduces regression risk during updates and enables focused assurance/maintenance. (Emphasized in SWEHB certification guidance.)
Demonstrate applicable human‑factors design principles in the software
HSI evidence (clear displays, alerts, error tolerance) mitigates operator error and automation surprise—frequent contributors to unsafe states in lessons learned and SWEHB checklists.
Section: Development
Item
Rationale
Access to the software operational plans or user’s manual
Operational manuals drive correct crew/operator actions; unclear procedures have historically led to unsafe system states—documented guidance is essential.
Explanation of the Fault Tolerance approach used in the design
Development evidence must confirm the implemented redundancy, monitoring, and recovery match the approved design/FDIR strategy.
Access to the source code
Assurance/IV&V require code access to assess correctness, safety patterns, and compliance; “code is the design” for verification in SWEHB practice.
Approval data for all AI uses in flight software before deployment
The human‑rated certification checklist in SWEHB requires governance of novel tech; AI decisions must be bounded, transparent, and verified before mission use.
Demonstrate correct AI confidence levels for critical decisions/predictions
Accurate confidence cues preserve appropriate human trust; misleading confidence can induce hazardous operator actions (SWEHB human‑rated checklist).
Demonstrate AI transparency/accountability in critical flight software
Transparency and auditable behavior enable assurance teams to verify AI outputs, edge cases, and failure handling consistent with safety requirements (SWEHB PAT guidance).
Access to defect reports, anomaly logs, and residual risk acceptance
Defect trends and residual‑risk approvals provide readiness evidence and ensure risks are visible and accepted prior to flight (SWEHB PAT‑082).
Access to tailoring/waiver/deviation and TBR/TBD/FWD closures
Tailoring/waiver records show what SWEHB/NPR expectations were modified and how verification gaps were closed—preventing undocumented process escapes.
Evidence that approved processes were followed during development
Deterministic timing & schedulability evidence prevent deadline misses and resource starvation—common latent hazards noted in SWEHB certification checklists.
Section: Verification & Validation
Item
Rationale
Access to the software test results
Test evidence must trace to requirements and hazards to prove correctness and safety under nominal/off‑nominal conditions (SWEHB).
Access to MC/DC coverage data for safety‑critical components
For safety‑critical logic, MC/DC helps reveal untested decision paths—improving confidence that critical branches cannot hide defects (SWEHB practice).
Static and dynamic analysis approach/results
Static/dynamic analyses expose memory, concurrency, and API defects early, complementing functional tests with deeper correctness checks (SWEHB PAT‑082).
Fault‑injection resilience under worst‑case conditions
Fault‑injection validates robustness of error handling and safe‑state transitions under realistic fault scenarios (SWEHB).
Handling spurious signals and invalid inputs
Defensive input handling and integrity checks are SWEHB safety‑critical design requirements to prevent unsafe behavior from noise or corruption.
Certification of software test environments
Accredited test environments assure fidelity so test results represent flight behavior—preventing false positives/negatives (SWEHB PAT‑082).
Cyclomatic complexity analyses results
Complexity correlates with defect likelihood and test effort; tracking supports risk‑based testing and maintainability (SWEHB checklist).
Issues/anomalies/defects list with unresolved‑item justifications
Residual issues require documented operational mitigations and rationale to ensure informed risk acceptance before flight (SWEHB).
Operational test results & resource margins (CPU/memory/throughput)
Resource margin evidence demonstrates the system sustains mission loads without entering unsafe degraded states (SWEHB).
Access to IV&V reports/findings & IV&V scope understanding
Independent assessment adds rigor and identifies latent risks; scope clarity ensures findings are dispositioned (SWEHB/SMA IV&V discussion).
Section: Hazard Analysis
Item
Rationale
Hazard analysis, FTA, FMEA
Hazard analyses formally identify software causes/contributions and define controls; they are the backbone for safety‑critical requirements and tests (SWEHB).
AI warnings & recommendations for anomalies
AI components must surface anomaly cues and recommended mitigations in time for operator/software safing to prevent hazard escalation (SWEHB PAT‑082 scope).
Operator Action Validation
Operator action validation ensures human‑software interactions are unambiguous and error‑tolerant—reducing unsafe actions under stress (SWEHB checklist).
Software safing procedures
Safing procedures must reliably place the system into known safe states on detection of hazardous conditions—captured in SWEHB safety‑critical design items.
Section: Configuration Management
Item
Rationale
Access to the software documentation
CM control of documentation prevents divergence between what is built, tested, and flown—frequent contributors to integration defects (SWEHB PAT‑082).
Access to the software change logs
Change history enables traceability and impact assessment for safety‑critical components/interfaces (SWEHB).
Version control, baseline definitions, audit records
Version/baseline and audits ensure the exact tested configuration proceeds to flight and prevent unauthorized changes (SWEHB checklist).
Section: Operational Procedures
Item
Rationale
Explanation of the software control sequences
Clear control sequences reduce operator confusion and ensure predictable behavior during time‑critical operations (SWEHB).
Explanation of any software manual safing data/processes
Manual safing provides a human‑initiated fallback when automation fails; procedures must be explicit, tested, and accessible (SWEHB).
Section: Cybersecurity
Item
Rationale
Encryption, authentication, secure coding, access control
Security controls protect command authority, data integrity, and system availability—security weaknesses can become safety hazards (SWEHB).
Penetration testing and vulnerability analysis results
Pen/vuln testing finds exploitable weaknesses before flight, supporting remediation and risk reduction (SWEHB checklist practice).
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3. Example Potential Safety Case for Human-Rated Software Certification
This safety case demonstrates that the software used in this human-rated mission adheres to rigorous safety, quality, and regulatory standards. Based on the evidence provided, the software is flight-ready and capable of supporting critical mission operations while ensuring the safety of the crew and spacecraft under both nominal and adverse conditions.
1. Requirements and Traceability
Argument: The software requirements are clearly defined, traceable, and aligned with safety-critical mission needs.
Evidence:
Comprehensive Software Requirements Specification (SRS) covering high-level mission-critical systems (e.g., navigation, propulsion, anomaly detection, life support, and abort operations).
Verified safety requirements (fault tolerance, redundancy, and safe initialization/termination).
Acceptable quality of detailed low-level safety-critical requirements, including specifics like algorithm designs and timing constraints.
A completed and validated Requirements Traceability Matrix (RTM) showing bi-directional traceability from requirements through design, code, and test results.
Reviewed system-level safety analyses to document "Must Work" (MWF) and "Must Not Work" (MNWF) requirements, prerequisite checks for hazardous commands, and mitigation strategies.
2. Software Design and Architecture
Argument: The software architecture is resilient, modular, and designed for fault tolerance and safety-critical operations.
Evidence:
Architecture documentation detailing modular fault isolation, redundancy, and resiliency mechanisms.
Block diagrams illustrating fault containment, fail-safe control paths, and separation of critical functions.
Documentation and analysis of safety-critical subsystems (e.g., propulsion, crew displays, navigation) with clearly defined responsibilities.
Verified Interface Control Documents (ICDs), ensuring compatibility between internal software, hardware systems, and external interactions.
Safety validation evidence for safeguards like fault containment, error detection, operator validation, integrity checks, and anomaly recovery processes.
Independent redundant system designs ensuring physical and logical separation to mitigate single points of failure.
Validation of fault-tolerant mechanisms, including cosmic radiation protection in CPU designs.
3. Hazard Analysis and Safety Evidence
Argument: All hazards associated with software functionality are identified, analyzed, and mitigated to acceptable levels of risk.
Evidence:
A complete Hazard Analysis Report (HAR) identifying software-driving hazards and the mitigation strategies in place.
Fault Tree Analysis (FTA) and Failure Mode and Effects Analysis (FMEA) showing robust fault prevention and recovery mechanisms or a completed System Theoretic Process Analysis (STPA) showing robust fault prevention and recovery mechanisms.
Time-to-effect (TTE) analyses ensuring hazardous conditions can be addressed by safing systems within operational thresholds.
Residual risk documentation showing resolution or acceptance of remaining risks by stakeholders.
4. Verification and Validation (V&V) Evidence
Argument: Rigorous testing, validation, and coverage analyses demonstrate software compliance with safety-critical requirements.
Evidence:
100% Statement Coverage.
100% Decision Coverage.
100% Modified Condition/Decision Coverage (MC/DC) for safety-critical components.
Unit testing, system integration testing, end-to-end validation, and operational flight simulations confirming that expected functional performance aligns with safety goals.
Validation of reused components (COTS, GOTS, OSS, MOTS) to ensure compatibility and reliable integration into human-rated environments.
Coverage analysis demonstrating:
Static analysis reports showing compliance with coding standards and identification/remediation of software defects.
Fault injection testing results validating responses to corrupted data, anomalies during power disruptions, and memory errors.
Worst-case response timing analysis confirming safing systems meet TTE requirements under degraded conditions.
5. Configuration Management and Change Tracking
Argument: Configuration management processes ensure version control and traceability for all software changes.
Evidence:
Documentation showing version-controlled baselines for flight-ready software and data loads, including configuration hashes and release notes.
Audit records verifying modifications, regression testing, impact analyses, and stakeholder approvals
6. Cybersecurity and Security Validation
Argument: The software architecture incorporates robust cybersecurity measures to mitigate threats in operation environments.
Penetration testing results validating resilience against cyberattacks and unauthorized system access during pre-launch and flight.
Vulnerability analysis reports confirming detection, resolution, and closure of security-related risks.
7. Defect Management and Residual Risks
Argument: All software defects have been resolved or mitigated to acceptable levels of residual risk.
Evidence:
Defect reports showing all open and closed defects categorized by severity and justifications for acceptance of residual risks.
Logs documenting defect resolutions and testing data validating the outcomes of mitigation measures.
Residual risk acceptance documentation signed off by stakeholders, with sufficient evidence showing safe system behavior despite unresolved minor risks.
8. Resource Utilization and Performance Metrics
Argument: The software demonstrates sufficient resource margins and acceptable performance under normal and worst-case conditions.