A “third best” solution will usually incorporate new technologies not yet in common use. This is needed to achieve improved safety, performance, cost, and operability compared to existing solutions. Quite often, specific metrics for capability improvement will be established. The systems architects and systems engineers—the development team—will turn to the research community to find potential technological solutions to achieve the desired improved capability. The research community will, then, present a range of alternatives. When assessing these alternatives, how does the development team rank these in terms of maturity. One widely used approach in the aerospace industry is the Technology Readiness Level (TRL) scale developed by NASA. Shown below, it provides an orderly binning of the maturity of a technology based on the type of activity underway and what has been accomplished.
The TRL scale has nine levels—starting with a value of 1, for the first reporting of the experimental or analytical definition of the basic principles of a new technology, and ending with a value of 9 when the technology is in operational use. Moving up on the scale, step by step, is accomplished with the type of activity listed in the left column. The step’s activities are considered to be completed when the measure of merit listed in the right column, often with specific quantitative metrics, is achieved and reported.
TRL 6 is the key threshold for assessing readiness to be used in a new product
In tracking up the list of the types of activity, the transition of a new technology out of the research lab and into a system development program begins at level 5 or 6, depending on the scope of the technology. What the development team looks for and what the researchers want to “sell” is a technology that has been shown to meet measurable quantitative metrics such as weight and performance. At TRL 5, the technology will have been successfully demonstrated using a component or breadboard in a relevant environment. At TRL 6, the new technology would have been included in a technology demonstration program—probably with several other technologies also being developed—where specific minimum quantitative metrics have been demonstrated in a relevant environment. In other words, the technology has been shown to actually work as intended and achieve better results that the state-of-the-art alternatives.
For most significant new technologies, completing TRL 6 is the technology transition threshold. When TRL 6 has been achieved, besides knowing that the technology will actually work, the expected cost, weight, and performance of the new technology is also known. The development team can then use this information to perform trade studies to determine which technologies enhance the overall cost and performance of a new product and which don’t. From the resulting basket of potential benefiting technologies, the development team will select those that, in their view, best achieve the product’s cost, schedule, and performance goals. This selection process is not without controversy as it often creates a form of “competition” between the researchers and the systems engineers over what new technologies to include or exclude.
Application to building a near-term spacefaring logistics infrastructure
Moving forward with building a spacefaring logistics infrastructure will require the careful selection of technologies to ensure that “third best” solutions—those that can be undertaken without unacceptable cost or delay—are selected. History has shown that it is quite easy for a program to be substantially delayed, or even cancelled, due to the poor selection of technologies that were insufficiently mature. The TRL scale helps to identify useful “third best” technology choices leading to likely success and those whose selection will lead to likely program delays and cost increases, and, potentially, cancellation.