ICT2014 Abstracts

The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) is a robust radioisotope powered thermoelectric space power system.  Fueled over five years ago, the first flight unit is successfully providing power to the Mars Science Laboratory rover Curiosity on the surface of Mars.  The MMRTG contains segmented thermoelectric (TE) couples that use N-type lead telluride and P-type lead tin telluride and TAGS.  These TE materials have been successfully used by Teledyne Energy Systems (TESI) for decades for space power and other applications and are among the very small number of TE materials mature enough to be used in high reliability power systems. 

Many promising new TE materials have been investigated over the years but few have been developed to the level where they could be considered for practical, long life systems.  The Jet Propulsion Laboratory (JPL) has worked with many TE materials  over the years  and has pioneered the development of skutterudite materials for TE applications.  Through materials testing and interface development they have brought the skutterudite materials to a level of maturity where the potential system performance increases offered by the material properties can be measured in a full couple. 

A NASA technology transfer program has been initiated at TESI, in collaboration with JPL, to bring the skutterudite thermoelectrics to production status and demonstrate the long term performance of couples and modules made from these promising materials.  The feasibility of integrating them into the MMRTG system to create an enhanced MMRTG will be investigated.  Initial studies have been performed and, with only minor modifications to the MMRTG which allow a hot junction temperature of 873K, the current MMRTG couples can be replaced with an equivalent number of skutterudite couples and provide a significant power increase.  Efficiency gains of 24% at beginning of life and 50% at the end of a 14 year mission appear likely.