One thing to remember is that any probe past Mars is almost certainly going to use an RTG over solar panels. This means that you will always have an exponentia

One thing to remember is that any probe past Mars is almost certainly going to use an RTG over solar panels. This means that you will always have an exponentially decaying power supply (wattage goes down over time if you use it or not). This is how voyager was powered, and because of the power drain, they had to turn off more instruments as time goes on.