Readiness levels for spacecraft information technologies

The New Millennium Program (NMP) seeks to advance space exploration through the maturation of promising spaceflight technologies. NMP, like many other organizations, relies upon Technology Readiness Levels (TRLs) as a key indication of technology advancement, and assesses development progress against this generalized metric. A given technology\´s TRL is based upon our ability to predict how the technology performs in various applications, and therefore depends on the environment in which the technology has been tested and validated. Testing begins in the laboratory, advancing through ever-improving simulations ad testbeds, until finally actual in-space validation is achieved. This process is well understood for space hardware and has been applied for many years. Presented in this paper is a modified interpretation of the traditional TRLs based on J. Markins (1995) aimed solely at information technologies. The intent of this new set of definitions is twofold: first, to enable a definitive measurement of progress among developing information technologies for spacecraft; and second, to clarify particular challenges and requirements that must be met as these technologies are validated in increasingly realistic environments. The first goal of this paper reflects NMP\´s need to verify clear and defensible progress of technology development on the path to spaceflight. The second goal serves to answer the question of what salient features of the space environment are important to technology developers. To answer this second question, we will revisit the notion of the "relevant environment", an environment that adequately stresses the technology to provide sufficient confidence in the results. This paper includes a direct comparison between the traditional TRLs and the modified definitions specific to information technologies. We also discuss two representative examples to illustrate this process.