• Since fusion has not yet been perfected, all nuclear power would produce energy by the process of nuclear fission
• In nuclear fission, the heavy nucleus of an atom is made to split into two fragments of roughly equivalent masses; this process is accompanied by large releases of energy - it is this process that takes place in nuclear power reactors and in atomic bombs
• In satellites, nuclear power is created in Radioisotope Thermoelectric Generators (RTG's)
• Nuclear power requires more volume then a normal battery; it doesn't require as much surface area as solar cells
• Power from a nuclear reactor is, for our purposes, limitless; it won't run out before the satellite becomes useless for other reasons
• Nuclear power cannot be used for Earth-orbiting satellites because when its orbit decays, the satellite will fall back to Earth and burn up in the atmosphere, spreading radioactive particles over the Earth
• One danger of nuclear power sources is that if the rocket used to launch the satellite explodes before escaping the atmosphere, radioactive particles would be spread over the Earth
• This happened in the early days of satellites when a Russian satellite with a nuclear power source crashed in northern Canada, exposing the area to radioactive particles
• Nuclear power is effective in space exploration satellites going deep into space because they may travel too far from the sun to use solar panels; since a nuclear power source will continue to generate power for an extremely long time, the satellite will have power for all of its long journey in space
• Nuclear power sources are very efficient, very durable, and very expensive