Paranoid delusions about black helicopters hovering over an area will soon be out of date: The latest scary spy apparatus lives 20,000 feet up, turning 30 or more square miles into live video sharp enough to spot individual people walking around.

The system is called ARGUS, after the 100-eyed god of Greek myth, and fittingly, it works by hooking together hundreds of inexpensive image sensors like those found in mobile phones. The non-classified parts were featured last week in an episode of the PBS show "Nova" all about drones and surveillance (the ARGUS segment starts at the half-hour mark).

ARGUS has appeared in earlier reports, but in a much less detailed fashion. The "Nova" program shows how it might actually appear in action.

The current version uses 368 five-megapixel sensors, for a total of 1.8 gigapixels. But unlike other gigapixel camera systems, this one doesn't record still images — it produces video. That means that from four miles up, it can watch a roughly circular area up to six miles wide, tracking every car and person in real time.

The amount of data produced by the system is, naturally, immense, around 6 petabytes per day according to earlier reports.

ARGUS has yet to be deployed, although there were plans to send three to Afghanistan onboard a helicopter-like hovering unmanned aerial vehicle (UAV) called the Hummingbird, now defunct. The future of the system is, for now, classified...