The Selenide Saga: A Contribution Toward a History of the Selenide Isotope Generator

Abstract

In the mid to late 1970s, the U.S. Department of Energy and its predecessor agencies supported studies on a Selenide Isotope Generator (SIG) that was to power the proposed Jupiter Orbiter Probe Mission (renamed the Galileo mission in 1978). Early studies projected a 1981 generator design with an efficiency of 10.5% (compared to then state-ofpractice efficiencies of under 7%) and a specific power of 6.6 We/kg (compared to then stateof-practice specific powers of 4.2 We/kg). Higher efficiencies were promised in the future: 11% (1983) and 13.5% (1985). As the experimental work continued evidence of degradation of the thermoelectric materials began to emerge, leading to the cancellation of the SIG program in 1979. This paper is a contribution to a history of the SIG program with suggestions for lessons that can be learned to aid future radioisotope power source (RPS) programs. "The disadvantage of men not knowing the past is that they do not know the present."

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