We humans have a history of using nuclear power in space to power probes that can’t be sufficiently powered otherwise. The simplest of these generators are Radioisotope Thermoelectric Generators.
RTG’s essentially use the fact that radioactive isotopes produce heat as they decay. The temperature differential between the isotope and the outer skin of the ship allows for power generation. RTGs have been used on mars probes as well. They’re comparatively simple and cheap, but don’t produce whopping great amounts of power, making them ideal for satellite operations.
More complex nuclear reactors have also been used, but the main issue with power generation using nuclear methods is that it generates a fair amount of heat, and space doesn’t carry the heat away (it must instead be radiated away) so if you have a lot of power generation you also need large radiators, which might become too large or complex for your satellite if you want to really ramp up the power.
But for most applications I’d say go nuclear. What’s the worst that can happen?