A Progress Report on the eMMRTG

A multimission radioisotope thermoelectric generator (MMRTG), developed by the US Department of Energy for the National Aeronautics and Space Administration, powers the Mars Science Laboratory Curiosity rover on Mars. New thermoelectric couples (TECs) have been developed in recent years that offer significant improvements over the TECs used in the MMRTG. The maturity of the new TECs and the design flexibility of the MMRTG enable a low-risk system upgrade that is predicted to substantially enhance the MMRTG's performance. System design trades are looking at changing the TECs and increasing the hot-side temperature to find the best combination of performance and program cost in this enhanced MMRTG (eMMRTG). Initial studies indicated that a low-risk enhancement would be to use skutterudite (SKD) materials developed at JPL to form TECs for the eMMRTG. Simply replacing the PbTe/TAGS TECs with SKD TECs and making a few low-risk modifications to the MMRTG design could potentially provide a 25% increase in power output at beginning of life (BOL). More important than the BOL power output increase is the end of design life (EODL) power output increase. With the anticipated lower degradation rate of the SKD materials, it is anticipated that the EODL power output will be more than 50% higher than for the MMRTG (with EODL defined as 17 years from fueling). This paper presents an overview of the results of the initial trades leading to the pursuit of the eMMRTG and the progress made since those were concluded.