Radioisotope thermoelectric generators (RTGs) are the power plants of the interplanetary spacecraft. Or at least they have been for going on 50 years now. But they have significant drawbacks, the primary one being that they’re heavy. Even modern-day RTG designs run into the hundreds of kilograms, making them useful for large-scale missions like Perseverance but prohibitively large for any small-scale mission that wants to get to the outer planets. Solar panels aren’t much better, with a combined solar panels and battery system, like the one on Juno, coming in at more than twice the weight of a similarly powered RTG.
An improved radioisotope thermoelectric generator could dramatically reduce the weight of interplanetary missions
