Conclusion

While extensive efforts were made in the United States and the Soviet Union to develop space-based fission power generators (SPGs) until the early 1990s, and although more than thirty SPGs were deployed in low Earth orbit by the Soviet Union in the 1970s and 1980s, no SPGs have been launched since 1988. The collapse of the Soviet Union, the priority given to a permanent human presence in Earth orbit with the International Space Station, and advances in space-based photovoltaic technologies no longer justified continuing these costly efforts. Thus, the power needs of space systems (satellites, orbital vehicles, space stations, exploration probes, rovers) are now largely met by photovoltaic technologies using solar panels combined with batteries. And when solar energy is unavailable, radioisotope generators, with a power output limited to a few hundred watts, have so far been sufficient to...