Overview of the issues related to the use of Radioisotope Power Systems in European space missions

Space nuclear power is the most viable energy source for some space missions, such as the exploration of outer planets or the exploration of a planetary surface with long day/night cycles. Thanks to high energy densities, certain isotopes can generate considerable amounts of heat for long time periods, independently of insolation levels; this heat can be converted into electrical power, or used to keep suitable temperatures inside the spacecraft. However, the presence of radioactive material implies new requirements, to properly manage all the aspects related to safety. A common European safety framework is required for Europe and ESA to independently manage radioisotope power systems: a significant amount of programmatic effort in many domains and by different entities will therefore be required, but the long and wide-ranging experience of other countries in dealing with space nuclear power systems could be an appropriate starting point.