Vision and Voyages for Planetary Science in the - Solar System ...

particular technology item. In general, low-TRL refers to technologies just beginning to be developed
(TRL 1-3), and mid-TRL covers the phases (TRL 4-6) that take an identified technology to a maturity
where it is ready to be applied to a flight project (Figure 11.1).
FIGURE 11.1 Technology Readiness Levels for space missions. SOURCE: NASA.
A primary deficiency in past NASA planetary exploration technology programs has been 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 technological capability 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.
Technology Infusion Initiatives
In recent competed mission solicitations, NASA provided incentives for infusion of new
technological capabilities in the form of increases to the proposal cost cap. Specific technologies
included as incentives were the following:
• Advanced solar electric propulsion, NASA’s Evolutionary Xenon Thruster (NEXT),
• Advanced bipropellant engines, the Advanced Material Bipropellant Rocket (AMBR),
• Aerocapture for orbiters and landers, and
• A new radioisotope power system, the Advanced Stirling Radioisotope Generator (ASRG).
PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION
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