Operational flights of the Space Shuttle have initiated an exciting new era of space util,- zation and habitation. In fact, the start of the Third Millennium will be highlighted by the establishment of man\u27s extraterrestrial civilization. There are three technical cornerstones upon which human expansion into space will depend: 1) compact energy systems, especially power and propulsion modules;
2) the ability to process extraterrestrial materials anywhere in heliocentric space; and
3) the development of permanent human habitats in space.
The manned and unmanned space missions of the future will demand first kilowatt, then megawatt, and eventually even gigawatt levels of power. Energy, especially nuclear energy, will be a most critical technical factor in the development of man\u27s extraterrestrial civilization.
This paper examines leading space nuclear power technology candidates. Particular emphasis is given the heat-pipe reactor technology currently under development at the Los Alamos National Laboratory. This program is aimed at developing a 10-100*kWe, 7-year lifetime space nuclear power plant. As the demand for space-based power reaches megawatt levels, other nuclear reactor designs including: solid core, fluidized bed, and gaseous core, are considered
