NASA technical writing

Create a durable technical record from supplied engineering or scientific evidence. Make it possible for a qualified reader to understand what was done, what was observed, and what follows.

Protect the technical record

• Preserve measurements, units, tolerances, significant figures, uncertainty, calibration,

configuration identifiers, test conditions, and data exclusions.

• Do not improve, average, convert, or round a value unless the method and authority are supplied.
• Distinguish source data, calculated results, observations, interpretations, requirements,

limitations, and recommendations.

• Do not turn correlation into causation or an untested explanation into a finding.
• Mark missing evidence, anomalous data, and unresolved discrepancies for technical review.

Frame the report

1. State the purpose: the question, requirement, or decision the work addresses.
2. Define scope, system boundary, applicable configuration, and excluded conditions.
3. Identify governing requirements, prior work, assumptions, and acceptance criteria.
4. Summarize the method and principal result without overstating certainty.
5. Choose sections that fit the artifact: background, apparatus, method, results, analysis,

limitations, conclusions, and recommendations.

Make methods reproducible

• Describe hardware, software, materials, environment, setup, calibration, sampling, controls,

and procedure at the precision needed to repeat or evaluate the work.

• Record departures from the planned method and explain their effect on interpretation.
• Define variables, coordinate systems, reference frames, and conventions before use.
• Keep chronological procedure separate from the rationale for choosing the method.
• Cite the source of externally supplied data and identify any transformation applied to it.

Report evidence before interpretation

• Present observed and calculated results without evaluative language.
• Tie every figure and table to a question in the text. State what the reader should inspect,

while keeping interpretation out of captions when that distinction matters.

• Give units in headings or labels and define error bars, limits, and missing values.
• Compare results with requirements or predictions using the stated acceptance method.
• Explain anomalies and competing interpretations; do not discard inconvenient results silently.

Draw bounded conclusions

• Support each conclusion with a specific result, analysis, or cited source.
• Limit a conclusion to the tested configurations and conditions.
• State confidence and uncertainty in terms supported by the method.
• Separate a finding from a recommendation. Give each recommendation an evidence-based reason.
• Identify limitations, unresolved issues, and work needed before a broader claim can be made.

Preserve traceability

Maintain a compact mapping from requirement or question to method, evidence, result, and conclusion. Use stable identifiers for tests, datasets, configurations, and requirements. Keep references specific enough that a reviewer can locate the exact source version.

Avoid

• promotional claims, mission rhetoric, and adjectives that substitute for measured performance
• conclusions introduced before the supporting result
• mixing planned, observed, inferred, and recommended states
• unexplained unit conversion, precision changes, smoothing, or omission of outliers
• figures and tables that repeat prose without improving comparison or traceability
• implying NASA authorship, approval, endorsement, or compliance with NASA publication review

Final pass

Audit every number, unit, configuration, and conclusion against the evidence. Confirm that scope, method, conditions, anomalies, limitations, and unresolved issues are visible. Require the applicable engineering, scientific, export-control, and publication reviews before release.

Read [references/SOURCE.md](references/SOURCE.md) only for source, attribution, licensing, or maintenance questions.