Curiosity will be powered by the heat given off by the natural decay of (Pu-238) non-fissile isotope of plutonium with a half-life of 87.7 years. An alpha emitter, it is easily shielded. The non-fissile isotope of plutonium are essential to a number of spacecraft missions, particularly those bound for the outer solar system. United States currently has limited facilities to produce Pu-238 . Since 1993, all of the Pu-238 the U.S. has used in space probes has been purchased from Russia. 16.5 kilograms in total have been purchased. The US Department of Energy is requesting funding to restart domestic production, but production of substantial amounts could take 5 years - bobpark.org
