FIGURE 3.1.1 Technology readiness level scale. SOURCE: Courtesy of NASA.

NASA employs a technology readiness level (TRL) process to assess the flight readiness of a given technology under development on the basis of its level of maturity (see Appendix D in this report). The TRL is rated on a scale of 1 to 9 depending on the degree of concept development, analytic and empirical validation, and ultimately, flight validation (see Figure 3.1.1).

TRL 9: Actual system “flight proven” through successful mission operations

TRL 8: Actual system completed and “flight qualified” through test and demonstration (ground or space)

TRL 7: System prototype demonstration in a space environment

TRL 6: System/subsystem model or prototype demonstration in a relevant environment (ground or space)

TRL 5: Component and/or breadboard validation in relevant environment

TRL 4: Component and/or breadboard validation in laboratory environment

TRL 3: Analytical and experimental critical formula and/or characteristic proof-of-concept

TRL 2: Technology concept and/or application formulated

TRL 1: Basic principle observed and reported

SOURCE: NASA In-Space Propulsion Web site at http://www.grc.nasa.gov/WWW/InSpace/when.html.