Abstract :
Next time you look up into a cloudless blue sky, it is worth remembering that someone up there might be watching you. Should you be anywhere near a military installation, like an airfield or missile base, you could be within the field of view of an orbiting spy in the sky, a satellite carrying cameras so powereful as to be capable of detecting that you are a mere civilian and not a guard or sentry in uniform. Space research and manned missions may grab the headlines, but military satellites grab the budget, outnumbering their more glamorous counterparts by three to one
