To perform all its duties, the spaceship will need power, and the Multi-Mission Radioisotope Thermoelectric Generator is partially tasked with supplying it. MMRTG, for short, it’s the same piece of hardware that was included on several other machines sent to distant worlds, including Martian rovers Curiosity and Perseverance. Long before that, earlier variants were flown on the Pioneer spacecraft, among others.
The reactor’s job is simple: provide power by turning heat generated by the natural decay of plutonium-238 into electricity. The advantage of this system is that it has no moving parts; hence it’s not prone to breaking down.
Handling the conversion from heat to electricity are thermocouples, parts one also finds in air conditioners or refrigerators. A thermocouple is made of two plates made from different metals that make up a closed electric circuit.
Back to Dragonfly, this will be the first attempt humanity will be making at landing something on a world so distant. Aside from Mars and its obvious (to some) life-rich past, Titan’s surface “is one of the most Earthlike places in the solar system, albeit at vastly colder temperatures and with different chemistry.”
A perfect place to study, of course.