Space Nuclear Fission Powers Systems

The use of fission-powered nuclear generators to supply electricity in space was considered as early as the dawn of the nuclear age and led to large-scale developments in the 1960s and 1980s. These space-based nuclear fission power generators (GENSF) were commonplace in the 1970s and 1980s: they were installed on Soviet RORSAT military satellites used for maritime surveillance. But since 1988, no SPFG has been launched into space, and the last major “historic” SPFG development program was prematurely terminated in the United States in 1993. Photovoltaic generators, which had made great strides, effectively met the power needs of satellites that had become less energy-intensive (again thanks to technological advances); radioisotope thermoelectric generators producing a few hundred watts were sufficient for scientific exploration missions that photovoltaics could not support; and ambitious space missions requiring SPP required budgets that were no longer feasible. Two major developments are now changing the landscape: the dawn of a new era of human space exploration, notably with the Artemis program targeting first the Moon and then Mars; and the sharp resurgence of geopolitical tensions, which is having repercussions in both space exploration and the military use of cislunar space. Thus, since 2010, we have witnessed a gradual revival of GENSF development programs, primarily in the United States, Russia, and China. The main civilian applications targeted are powering lunar (and eventually Martian) bases, for which an initial demonstration on the Moon’s surface is planned by 2030 as part of the Artemis program, and nuclear electric propulsion, with, according to the Russian space agency, the in-flight demonstration of a space tug equipped with electric thrusters powered by an SPS.

This article is intended for engineers who are curious to understand what these GENSFs are, what potential needs they address, to what extent their design and safety challenges differ from those of land-based nuclear micro reactors (the differences are substantial), what technological options are available, and what challenges they present. Those undertaking research on the subject will find numerous bibliographic references here that will allow them to explore each of the topics covered in greater depth.