Radioisotope Thermoelectric Generator is an electrical generator.

  • It uses a radioactive material as the fuel and uses the fact that radioactive materials generate heat as they decay into nonradioactive materials.
  • This released heat is converted in to electricity by using Seebeck effect using an array of thermocouples.
  • The output obtained in a RTG is a steady output voltage and its power capacity is a few 100 W.
  • RTG provides an uninterrupted and reliable source of heat and electricity in remote and harsh environment such as deep space.
  • Considered as a type of battery and so used as power sources in satellites, space probes and unmanned remote facilities.


  • It provides power and heat for spacecrafts to many years.
  • It is also known as space batteries or nuclear batteries.



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