How do deep-space probes keep working for decades?

Deep-space probes must survive far from the Sun, where solar power becomes weak and temperatures are extremely low. For missions like Voyager 1 and Voyager 2, NASA used radioisotope thermoelectric generators, or RTGs, which convert heat from plutonium-238 decay into electricity. These spacecraft also need fault-tolerant computers, redundant systems, and careful management of power-hungry instruments. Voyager 1, launched in 1977, is still returning data from interstellar space, showing how durable such engineering can be. Mission teams often power down nonessential instruments over time to stretch the spacecraft’s lifespan.