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Fission technology can enable rapid, affordable access to any point in the solar system. If fission propulsion systems are to be developed to their full potential; however, near-term customers must be identified and initial fission systems successfully developed, launched, and utilized. Successful utilization will simultaneously develop the infrastructure and experience necessary for developing even higher power and performance systems. To be successful, development programs must devise strategies for rapidly converting paper reactor concepts into actual flight hardware. One approach to accomplishing this is to design highly testable systems, and to structure the program to contain frequent, significant hardware milestones. This paper discusses ongoing efforts in Russia and the United States aimed at enabling near-term utilization of space fission systems. *SNAP-50 / SPUR *Advanced Liquid Metal Cooled Reactor Program *Medium-Power Reactor Cooled Electric Power *Advanced Space Nuclear Power Experiment (MPRE) Reactor (710 Reactor) Program (SPR) *High-Temperature Gas-*Thermionic Technology Program (1963-1973) *SPAR / SP-100 *Flight Topaz *Multi-Megawatt Program *Thermionic Fuel Element *Space Nuclear Thermal Rocket Verification Program Air Force Bimodal Study *DOE 40 kWe Thermionic Reactor Program PrOgram *SP-100 Previous and Ongoing Russian Nuclear Thermal Rocket Research From 1950-1980 a prototype nuclear rocket engine (NRE) with a heterogeneous core, carbide fuel, a thrust of 36 kN, a specific impulse of 920 s, and an operational lifetime of 1 hour was developed and successfully ground tested in Russia (Demyanko et al., 2002). From 1970-1988 thirty-one spacecraft powered by the first Russian nuclear power plant (NPP) "Buk" (3 kWe. thermoelectric power conversion) were launched into near-Earth orbits (Ponomarev-Stepnoi, 2000). The world's first NPP 'Topol" using thermionic energy conversion and providing 5 kWe of power, well-known as 'Topaz", was tested in flight on two spacecraft in 1987-1988. Electricity from the Topaz system was used to power an electric propulsion (EP) subsystem. The 6 kWe thermionic NPP "Enisei" (Topaz-2) underwent the complete cycle of proto-flight tests. Experimental studies with the NPP Topaz-2 were performed in the early 1990's in the USA within the framework of the Nuclear Electric Propulsion Space Test Program-NEPSTP. Methods and means were developed in Russia to assure radiation safety of spacecraft with NPP both in normal operation and emergency situations. Presently in Russia research related to the next use of fission energy in space is being conducted in accordance kith the Space Nuclear Energetics Progress Concept approved by the Russian Federation government in February, 1998 (Rossiiskaya Gazeta, 1998). The Concept foresees the generation of technology advances providing the opportunity to develop nuclear systems at power levels up to 100 kW and lifetimes no less than 5-7 years by 2010, and solving a wide range of promising tasks associated with their use both in near space and i...