Calibrating the Technology Readiness Level (TRL) scale using NASA mission data

This paper seeks to assess the qualitative and quantitative aspects of the Technology Readiness Level (TRL) scale in order to understand its ability to provide estimates of the forward costs of developing a new technology to a state of flight readiness. TRLs are in common use throughout NASA, industry and military organizations and are characterized by being easy to determine using a set of well-defined parameters. However, the TRL scale is not calibrated to any consistent unit and the relative size of TRL steps are not linear and can vary for different technologies. We use archived cost data from a variety of recent NASA flight missions and from several technology-heavy instrument suites on the Mars Science Laboratory (MSL). Development costs are extracted at the time of several NASA life cycle review milestones. We relate the project requirements associated with these defined milestones with approximate TRL steps and use the cost data as a proxy for TRL step costs. When corrected for programmatic variations in time spent at each TRL step, the NASA mission data demonstrated a 30% reduction in variability, illustrating how unexpected events mask a more stable progression of technology development. A calibrated TRL scale is determined with an “S-curve” shape to TRL growth. The steepest step sizes are in the TRL 6 to 8 range, matching the region of technology maturation known to be a difficult barrier to traverse.