A sketch of the 1980s/90s SP-100 space-based nuclear reactor, designed to provide 100 kilowatts of electrical power continuously for years on end. It would have been just the thing for applications where solar panels would not have been practical, such as deep space probes or military systems that need to be somewhat maneuverable. One might thing that replacing vast PV arrays with a small reactor would have made the satellites less visible… and on radar and likely visible light, that’s probably true. but that reactor and its radiators would have been quite visible in infra-red, apparent to any IR sensor pointed int its general direction. The sketch below shows not only the tests and progress that had been done on the SP-100, but also a conceptual payload of an undefined sort. It seems to be festooned with sensors.
