TABLE 2.1 NASA Technology Readiness Levels

TRL Definition Hardware Description Software Description Exit Criteria
1. Basic principles observed and reported. Lowest level of technology readiness. Scientific research begins to be translated into applied research and development. Examples might include paper studies of a technology’s basic properties. Scientific knowledge generated underpinning hardware technology concepts/applications. Scientific knowledge generated underpinning basic properties of software architecture and mathematical formulation. Peer reviewed publication of research underlying the proposed concept/application.
2. Technology concept and/or application formulated. Invention begins. Once basic principles are observed, practical applications can be invented. The application is speculative, and there is no proof or detailed analysis to support the assumption. Examples are still limited to paper studies. Invention begins, practical application is identified but is speculative, no experimental proof or detailed analysis is available to support the conjecture. Practical application is identified but is speculative, no experimental proof or detailed analysis is available to support the conjecture. Basic properties of algorithms, representations and concepts defined. Basic principles coded. Experiments performed with synthetic data. Documented description of the application/concept that addresses feasibility and benefit.
3. Analytical and experimental critical function and/or characteristic proof of concept. At this step in the maturation process, active research and development (R&D) is initiated. This must include both analytical studies to set the technology into an appropriate context and laboratory-based studies to physically validate that the analytical predictions are correct. These studies and experiments should constitute “proof-of-concept” validation of the applications/concepts formulated at TRL 2. Analytical studies place the technology in an appropriate context and laboratory demonstrations, modeling and simulation validate analytical prediction. Development of limited functionality to validate critical properties and predictions using non-integrated software components. Documented analytical/experimental results validating predictions of key parameters.
4. Component and/or breadboard validation in laboratory environment. Following successful “proof-of-concept” work, basic technological elements must be integrated to establish that the pieces will work together to achieve concept-enabling levels of performance for a component and/or breadboard. This validation must be devised to support the concept that was formulated earlier and should also be consistent with the requirements of potential system applications. The validation is relatively “low-fidelity” compared to the eventual system: it could be composed of ad hoc discrete components in a laboratory. A low fidelity system/component breadboard is built and operated to demonstrate basic functionality and critical test environments, and associated performance predictions are defined relative to the final operating environment. Key, functionally critical software components are integrated, and functionally validated, to establish interoperability and begin architecture development. Relevant environments defined and performance in this environment predicted. Documented test performance demonstrating agreement with analytical predictions. Documented definition of relevant environment.

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