We have satellites that can read the text on your iPhone screen
Do you have a citation for this?
Do you have a citation for this?
In addition to the (currently) unavailable high-resolution imagery which would be required, atmospheric distortion would render any text illedgible, and it seems very unlikely the individual characters would be resolvable. Many of the techniques used to reduce/compensate for atmospheric distortion in telescopic imaging are not possible in Earth observation.
Also, things will get worse since satellites are not really the future. Solar-powered high-altitude planes that can keep themselves aloft for years are potentially much cheaper to launch and operate, and much more flexible, so I'm guessing this is where things will be heading in the next few years. They may be easier to detect and shoot down, true, but they seem perfect for domestic surveillance ops.
Found a youtube video: https://www.youtube.com/watch?v=iTXnJF5MnHQ
Check that one as well, DARPA's 1.8 gigapixel camera for continous monitoring of, well, small cities from altitudes up to 20 000 feet. And something tells me that's not the real state of the art.
It's off by orders of magnitude. KH-11 had/has a 2.4m primary mirror. Wikipedia (correctly) says the following:
>"Assuming a 2.4-meter mirror, the theoretical ground resolution with no atmospheric degradation and 50% MTF would be roughly 15 cm (6 inches). Operational resolution would be worse due to effects of the atmosphere"
16-point typeface is 5.8mm tall, so you probably need at least 0.58mm resolution to read it, and 2mm resolution to separate the characters.
2mm/150mm = 1/75 = 0.013
You need 75x better resolution than KH-11 to resolve characters.
0.58mm/150mm = 0.0038
You need (1/0.0038) 259x better resolution than KH-11 to read 16 point text.
You need ~2-2.5 orders of magnitude better resolution than the largest known earth-imaging satellite can provide, and that is assuming the phone is perpendicular to the satellite with no atmospheric distortion.