A Perspective on the NASA Space Power and Energy Storage Roadmap National Research Council Panel Power Workshop March 21, 2011 H. Sterling Bailey, Ph. D., P.E. Consultant Bailey Engineering and Management, Inc.

Fission Power Systems Benefits to NASA’s Enterprise Mission The tremendous value of environment independent, long life, reliable power in the 100’s of W e range has been abundantly demonstrated by the RTG’s powering Pioneer through New Horizons and Apollo However, there is considerable uncertainty about the availability of sufficient 238 Pu for the planned and desired future science missions Fission power systems offer affordable, robust, long life power from ~1 kWe through MWe’s based largely on established terrestrial technologies that will enable NASA to break free of current power constraints and that can be available on schedules and budgets consistent with NASA mission needs Abundant power for outer planet science missions Enabling for manned habitats, ISRU, high power electric propulsion ….. Development of qualified space fission power systems will be a truly Game Changing accomplishment for NASA by dramatically extending both science and exploration mission capabilities

High Priority Power Technologies Critical evaluation and potential development of 1 kWe class fission power systems options –e.g. solid core with heat pipes coupled to thermoelectrics Completion of the Fission Power System Technology Demonstration Unit –Map out the reactor feedback parameters required for stability Accelerated adaption of LMFBR technology to space –e.g. critical experiments to quantitatively validate reactor safety and operational parameters for candidate designs –Evaluation of higher temperature fuels (e.g. cermets) Development of MWe class concepts and evaluation of technologies required vs. available An integrated Nuclear Power and Propulsion group with appropriate DOE and Industry participation is the best way to deliver these technologies

Need for a Stable Fission Power Program Historically we have experienced several start and stop cycles, e.g. –SNAP 10A 1950s through mid ’60s –SP-100 early 1980’s through 1994 –Prometheus/JIMO –Affordable Fission Surface Power/ Fission Power Systems This lack of continuity results in an exceedingly small pool of experienced space nuclear power personnel –Retraining costs are high for government and industry –Value from prior work/investment is significantly reduced Acquisition and subsequent disposal of specialized equipment is very wasteful of government funds Industry confidence in real programs is very low –Willingness to invest is very questionable NASA should strive to establish a stable, broad program

Institutional Issues/Challenges In the current, low level Fission Power System project there is exceptionally good cooperation between the participating NASA Center and DOE Laboratory personnel NASA is the End User/Customer however, the Department of Energy has the singular legal authority and responsibility to develop fission power reactors for federal programs Therefore, DOE should be a full partner in space fission power system development to achieve maximum effectiveness This means that DOE should prioritize this within its charter and fund a reasonable part of the effort An agreement at the Administrator to Secretary level would be appropriate, OSTP participation may be needed Coordination of the congressional authorization and appropriation committees for NASA and DOE will be required

Conclusions Fission power systems from ~1kWe through MWe’s will enable and significantly enrich planned and desired science missions complimenting radioisotope systems and will enable exploration missions to fulfill NASA’s goals A practical step by step approach to these systems is proposed that builds on large terrestrial technology investments and accomplishments to significantly higher performance with measured risks A stable NASA/DOE program is required to achieve these systems and effectively utilize available resources A flexible set of power systems based on related technologies that will support a range of evolving mission requirements is needed to justify an ongoing, stable technology program