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Comment by wmeredith | Hacker News Reader

Well, in 1985 US Spy satellites (declassified in 2011) had a resolution of 2-3 feet[1]. "Keyhole-class" (KH) reconnaissance satellites have been orbiting the Earth for more than 30 years and reportedly have a resolution of 5-6 inches[2].

[1]http://news.yahoo.com/declassified-us-spy-satellites-reveal-...

[2]http://science.howstuffworks.com/question529.htm

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That is precisely why I mentioned modern, in particular would be interesting to know if given a good angle they can resolve phone number being entered on a cell phone with physical keyboard (nokia 3390 for example).

Not sure if troll. The answer is no. 5-6 inch resolution means that one pixel will represent 5-6 inches. You wouldn't even be able to see the phone.

Edit: Sorry, understood your comment now. The real problem isn't resolution, it's "getting a good angle". Unless your target and the satellite's orbit are magically aligned at a precise moment, you're going to have an extremely hard time getting a satellite into position in a reasonable time (the best commercial satellites can do is around 6 hours).

Parent knows this, and was asking what could be done with modern hardware, given that keyhole-class satellites have been up for 30 years.

Optical resolution doesn't follow Moore's law. There will certainly have been improvements, but not like we are accustomed to. Computers can be used to model the atmosphere and attempt to recover resolution, but the returns will diminish quickly.

As long as the laws of physics allow it, its possible.

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