Interesting. For a refresher I tracked down a SpaceDaily article, "The Satellite Wars">, that I came across recently. During combat operations it seems that satellite optical imagery was available about once per hour, using six Keyhole sats. There was also Lacrosse synthetic aperture radio coverage several times a day, and a flotilla of minor sats providing IR and radio intercept coverage.

What I wanted to get a handle on is the scope of doing what you suggest. It sounds like the security camera principle: Find the scene of the crime, then run the tape backward to see where the crooks came from. Or forward to see where they go. It'd be cool, but my rough estimate is that the entire US satellite surveillance fleet gave us about a one-hour resolution (effective frame rate), when for surveillance tasks like tracking cars, more like a minute or less would be better. We'd need to increase the size of the fleet by about 50-60, scaling from current technology.

Too good an idea to let go of...what about lots of microsats, whose imagery could be synthesized into higher rez composites? Lots of small drone aircraft? Blimps?

It seems like it's almost possible. Such a system would generate a firehose stream of data to be disseminated, analyzed, and stored, but the technology's just barely up to it.

Maybe it's a good thing it's still difficult, and if twere done, could be done only in a war zone. Ubiquitous surveillance is just too powerful a tool for most governments to resist. Witness the UK, with more surveillance cameras per capita than anywhere else on Earth. Home of the Magna Carta, and the birthplace of the Surveillance Society.