Abstract NASA has completed a series of top-down reviews of its missions and space technology programs with a strong focus on missions which can be done faster, at less cost and with better performance. In addition, NASA has created a new office, the Office of Advanced Concepts and Technology, with a strong customer focus on technology. As a result of these reviews a number of exciting options are being considered for space nuclear systems. Of course, the near-term ongoing NASA space nuclear program is the Cassini mission to Saturn which will use three radioisotope thermoelectric generators (RTGs). Beyond that NASA is studying a Pluto Fast Flyby mission which will challenge the space power community to produce a low-mass RTG. Another candidate RTG mission is the Mars Environmental Survey (MESUR) mission to emplace a number of probes on the surface of Mars to obtain a more global survey of the planet than was accomplished with the two Viking Landers. Looking toward the 21st century there are a number of exciting planetary missions, such as the Jupiter Grand Tour, Outer Planet Orbiters/Probes, comet/asteroid rendezvous/sample return, which are enabled or greatly enhanced by nuclear reactor power coupled with electric propulsion.