That's not how mission planning works. They don't start with something roughly like Juno and decide which planet to send it to. Rather, the planet and rough s

That's not how mission planning works. They don't start with something roughly like Juno and decide which planet to send it to. Rather, the planet and rough scientific mission is picked first, then the probe is designed around that. I guess you could just mean "There is an RTG shortage, so we can't send anything past Jupiter", but I don't think this is actually how the decision was made.