Q. With reference to radioisotope thermoelectric generators (RTGs), consider the following statements :

  1. RTGs are miniature fission reactors.
  2. RTGs are used for powering the onboard systems of spacecrafts.
  3. RTGs can use Plutonium-238, which is a by-product of weapons development.

Which of the statements given above are correct?

  • 1 and 2 only
  • 2 and 3 only
  • 1 and 3 only
  • 1, 2 and 3

Answer: (b) 2 and 3 only

Radioisotope thermoelectric generators (RTGs):
  • Radioisotope thermoelectric generators (RTGs) are power sources that convert the heat released by radioactive decay into electricity. They are commonly used in space missions to power spacecraft, especially in deep space where solar power is insufficient.
  • RTGs work by using radioactive materials like plutonium-238 or Strontium-90, which naturally decay and emit heat. This heat is then converted into electricity through thermocouples.
  • RTGs are usually the most desirable power source for unmaintained situations that need a few hundred watts (or less) of power for durations too long for fuel cells, batteries, or generators to provide economically, and in places where solar cells are not practical.
  • Sometimes referred to as “nuclear batteries,” RTGs are not fission reactors, nor is the plutonium the type that is used for nuclear weapons.
  • Applications:
    • RTGs are used in a variety of space missions, including:
      • Interplanetary probes: Voyager 1 and 2, Cassini, and New Horizons.
      • Lunar missions: Apollos 12 and 14-17, China’s Chang’e landers.
      • Martian rovers: Viking 1 and 2, Curiosity.
  • Advantages:
    • Long-lasting power: RTGs can provide reliable power for decades, making them ideal for long-duration missions.
    • No moving parts: This simplifies their design and increases their reliability, as they are less prone to mechanical failure.
    • Independence from solar power: RTGs can provide power in areas with low or no sunlight, such as deep space or shadowed regions of planets.
  • Disadvantages:
    • Radioactive material: The use of radioactive material raises safety concerns, especially during launch and reentry.
    • Cost: RTGs are generally more expensive than other power sources, such as solar panels.
    • Heat dissipation: RTGs generate a significant amount of heat, which needs to be managed to prevent overheating and damage to the surrounding components.