I think it's just a general term for things like satellites, space vehicles, ground-based radar or other grounded imaging, drones, etc without being specific a

I think it's just a general term for things like satellites, space vehicles, ground-based radar or other grounded imaging, drones, etc without being specific as to whether it's optical, IR, radar, etc, and also disregarding its mounting and domain of operation. Sort of in the same sense that "spectroscopy" in science can refer to a wide variety of instrumentation! :)