Important Changes in the NASA Planetary Science Division’s (PSD) Radioisotope Program

James Green, Director, Planetary Science Division NASA

For the last several years PSD has been investing in Advanced Stirling Radioisotope Generator (ASRG) technology with the intent to fabricate flight units for deep space missions. The advanced Stirling technology was selected to take advantage of its increased efficiency over the Multi-Mission Radioisotope Thermal Generator (MMRTG), since the supply of Plutonium-238 (Pu-238) was limited at the time.   Now, with the restart of the Pu-238 production project this year, we expect to have a sufficient supply of Pu-238 for radioisotope power well into the future.

With an adequate supply of Pu-238, and considering the current budget-constrained environment, NASA has decided to discontinue procurement of ASRG flight hardware.  We have given direction to the Department of Energy, which manages the flight procurement, to end work on the flight units.  The hardware procured under this activity will be transferred to the Glenn Research Center to continue development and testing of the Stirling technology.

For future planetary missions that require radioisotope power systems the flight-proven MMRTG will be made available.  It is important to note that the MMRTG and the ASRG were designed to provide the approximately the same electrical power output.

I am happy to discuss this decision at all the upcoming Assessment Group meetings and at the American Geophysical Union meeting next month where I will address any questions that you may have.

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