From Laboratory to Spaceflight
Given an appropriate technology program budget, the way in which the monies are allocated to the different phases of technology development should be informed both by the lessons of past efforts at technology infusion, and by the guideline that any technology to be used on a flight mission should be at technology readiness level 6 prior to the project’s preliminary design review. The technology readiness level (TRL) is a widely used reference system for measuring the development maturity of a particular technology item. In general, a low TRL refers to technologies just beginning to be developed (TRL 1-3), and a mid-TRL covers the phases (TRL 4-6) that take an identified technology to a maturity at which it is ready to be applied to a flight project (Figure 11.1).
A primary deficiency in past NASA planetary exploration technology programs has been an overemphasis on TRLs 1-3 at the expense of the more costly but vital mid-level efforts necessary to bring the technology to flight readiness. Many important technological developments, therefore, have been abandoned, either permanently or temporarily, after they have reached TRL 3 or 4. This failure to continue to mature the technologies has resulted in a widespread “mid-TRL crisis” that has, in turn, created its own unique set of problems for flight projects. A new flight project that desires to use a specific technology must either complete the development itself, with the concomitant cost and schedule risk, or forgo the capability altogether. To properly complement the flight mission program, therefore, the committee recommends that the Planetary Science Division’s technology program should accept the responsibility, and assign the required funds, to continue the development of the most important technology items through TRL 6. Otherwise it will remain difficult, if not impossible, for flight projects to infuse these technologies without untoward cost and/or schedule risk.