TABLE E-1 TRL Definitions, Descriptions, and Supporting Information

TRL Definition Description Supporting Information
1 Basic principles observed and reported Lowest level of technology readiness. Scientific research begins to be translated into applied research and development (R&D). Examples might include paper studies of a technology’s basic properties. Published research that identifies the principles that underlie this technology. References to who, where, when.
2 Technology concept and/or application formulated Invention begins. Once basic principles are observed, practical applications can be invented. Applications are speculative, and there may be no proof or detailed analysis to support the assumptions. Examples are limited to analytic studies. Publications or other references that outline the application being considered and that provide analysis to support the concept.
3 Analytical and experimental critical function and/or characteristic proof of concept Active R&D is initiated. This includes analytical studies and laboratory studies to physically validate the analytical predictions of separate elements of the technology. Examples include components that are not yet integrated or representative. Results of laboratory tests performed to measure parameters of interest and comparison to analytical predictions for critical subsystems. References to who, where, and when these tests and comparisons were performed.
4 Component and/or breadboard validation in laboratory environment Basic technological components are integrated to establish that they will work together. This is relatively “low fidelity” compared with the eventual system. Examples include integration of “ad hoc” hardware in the laboratory. System concepts that have been considered and results from testing laboratory-scale breadboard(s). Reference to who did this work and when. Provide an estimate of how breadboard hardware and test results differ from the expected system goals.


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