Nuclear energy for space craft is studied for deep space travel. Solar energy produces limitations with respect to power production as one moves farther from the Sun so it is necessary to make as much powerful energy as a spacecraft can produce without external energy sources. Safety procedures are important for nuclear spacecraft missions, which is a critical issue in commercial nuclear power plants (NPPs) (IAEA [International Atomic Energy Agency] 2010). There are two kinds of energy sources in deep space beyond the orbit of Mars. The safety analysis for the Cassini mission is seen in Figure 5.1. Similar analyses were used in Galileo and Ulysses missions (NASA [National Aeronautics and Space Administration] 1997). There are several missions to Jupiter shown in Table 5.1.