| Level 1 | Basic principles observed and reported |
| Level 2 | Technology concept and/or application formulated |
| Level 3 | Analytical and experimental critical function and/or characteristic proof of concept |
| Level 4 | Component and/or breadboard validation in laboratory environment |
| Level 5 | Component and/or breadboard validation in relevant environment |
| Level 6 | System/subsystem model or prototype demonstration in a relevant environment (Ground or Space) |
| Level 7 | System prototype demonstration in an operational (space) environment |
| Level 8 | Actual system completed and (flight) qualified through test and demonstration (Ground and Space) |
| Level 9 | Actual system (flight) proven through successful mission operations |