Overview of nuclear energy and power supply units for deep space and planetary science missions

In space applications, one of the main issues is to obtain an efficient power supply. There are various types of energy sources to produce electrical power which is needed for the operation of all active spacecraft systems and subsystems. Due to the dependency of distance from the Sun, solar energy source has limited application area. On the other hand, nuclear energy sources are widely preferred to provide electrical power during many deep space and planetary science missions. Using the radioactive decay process or fission reactor, nuclear energy is converted to thermal energy. This thermal energy can be used directly for heating issues or converted to electrical energy. Thermal energy is converted to electrical energy by means of both static and dynamic thermo-electric conversion technologies. An overview of nuclear energy technologies and nuclear energy based power systems utilized in the deep space missions take place in this paper.