ABSTRACT
Nuclear energy-through fusion and fission breeders-, solar energy and, to a limited extent, solid fossil fuels are the conceivable solutions for providing the inexhaustible bulk of the very long-term energy needs. There are many analogies and also some differences when considering the energy problem in comparison with the space mission. The technological base is available to exploit present and most future alternative energy sources. The energy strategies of the future have to be seen in the more general context of raw material resources, of which energy is the most important one. In recent years, many critical and often pessimistic analyses of the energy future have been published. The only major options foreseeable today for providing the bulk of the long-term energy needs are nuclear energy through fusion and fission breeders, solar energy and, to a limited extent, coal. The long-term success of nuclear fission energy, say from year 2030 onward, depends on the large-scale introduction of the breeder reactor.
