NASA-STD-7009B

NASA STD 7009B (approved March 5, 2024) is the latest revision of NASA’s technical standard formerly 7009A with 43 mandatory requirements guiding the development, use, and credibility assessment of modeling and simulation (M&S) across NASA activities.

In addition to the explicit requirements, NASA STD 7009B provides a framework for tailoring for the level of risk associated with the M&S results and defines concrete metrics to evaluate both model capabilities and the quality of the model‑development process.

These metrics range from Level 0: Insufficient evidence to Level 4, the best case, for example, in validation: all M&S outputs compare favorably with data from the real‑world system (RWS) across the full operational range in its real environment.

The standard mandates a risk-based approach: M&S credibility efforts must be proportional to the risk of making incorrect decisions based on the model. High-consequence applications (such as mission operations) require deeper verification, validation, and uncertainty analysis based on the model’s assigned criticality level. Appendix D defines three risk levels (red, yellow, green), considering both the model’s influence on the decision and the impact of that decision on people, equipment, finances, and the mission. A red level means that 7009B must be applied; a yellow level makes its use optional; and for green, its application is not recommended.

The M&S lifecycle follows defined phases:

• Development: includes planning, assumptions, and data sourcing.

• Verification: checks that the implementation meets its specifications.

• Validation: ensures the model accurately represents the real-world system (RWS).

• Use: deployment, uncertainty characterization, and reporting.

• Maintenance & Retirement: updating, monitoring, and archival.

Throughout this lifecycle, credibility assessments (embedded in the standard) ensure consistent evaluation across all stages.

• Verification answers: Did we build the model right? It confirms the model’s implementation meets its documented requirements and specifications.

• Validation answers: Did we build the right model? It confirms that the model accurately represents the real-world system (RWS) in its intended environment.

The corresponding handbook provides concrete guidance on methods such as code reviews, test cases, and sensitivity studies for verification, as well as comparison against experimental or historical data for validation, offering techniques underpinned by best practices.

Uncertainties must be identified, quantified, and propagated from input data through all model outputs. The standard requires documented uncertainty bounds, sensitivity analyses, and clear reporting of all uncertainty factors and limitations identified during development and use of the model to the decision makers. These 11 criteria, together with their associated rationale, support robust decision‑making and enhance reliability, particularly in areas with limited data or complex dependencies

Each model undergoes qualification for its specific use case. Qualification requires:

• A documented life‑cycle plan detailing purpose, assumptions, scope, and limitations.

• Performance evidence through verification and validation tests.

• Outcome of a structured Credibility Assessment (covering data pedigree, verification/validation rigor, uncertainty characterization, and use-case fit).

• Assignment of a credibility level, consistent with criticality category.
  These steps ensure traceability and documented fitness-for-purpose.

Supporting tools, such as numerical solvers, software frameworks, and third‑party libraries must also be qualified. This includes ensuring: 

• Version control and documentation are available for all components

• Tool verification demonstrates that each tool performs as intended, and

• Tool validation is conducted against reference problems or benchmarks.

• Assurance that tool use complies with NASA software assurance and quality standards, ensuring traceability and reproducibility.

In summary, NASA‑STD‑7009B and its supporting handbook establish a comprehensive, risk‑based foundation for qualifying models and simulations while addressing multiple sources of uncertainty.

• Free 2024 Version B: Modeling & Simulation Credibility and Lifecycle Requirements (NASA‑STD‑7009B)