This document discusses the history and prospects for converting highly enriched uranium (HEU) fueled space nuclear reactors (SNRs) to low enriched uranium (LEU). It covers SNRs historical uses of HEU, the potential for LEU and alternative fuels in SNRs, related policy considerations, the U.S. Department of Energy's HEU stockpile, international nonproliferation policies, and emerging nuclear and other technologies for powering activities in space.