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?

Statements 2 and 3 are correct. RTGs are NOT fission reactors; they generate electricity using the natural radioactive decay (not fission) of isotopes, with thermocouples converting the heat to electricity. RTGs have been widely used to power spacecraft like Voyager, Cassini, New Horizons, and the Curiosity and Perseverance rovers because they provide reliable power for decades where solar panels are impractical. Plutonium-238, the most commonly used RTG fuel, is indeed produced as a by-product of nuclear weapons material production processes (specifically from irradiating neptunium-237).