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Fw: NSA good guys

On Sat, Apr 19, 2014, at 10:44 AM, jim bell wrote:
> [I didn't get a bounce off of CP the first time]

Jim, it did post to the list the first time.  This has happened to me
before, as well:  I've received an off-list reply from someone to a
message (sent only to the list) long before I saw it post on the list. 
There is often a delay and I'm not sure why; I'll look at the path in
headers the next time it happens.

(Also, on-topic: you make some good points here!)



> From: "" <>
> 
> |     It may be possible, in the not-so-distant-future, to record
> |     people in ultra high definition from a mile away, but the
> |     'technology'  can be rendered rather useless with somthing
> |     like...this
> | 
> |     
> | 
> 
> 
> >At this time, it is possible to do facial recognition at 500 meters,
> >iris recognition at 50 meters, and heartbeat recognition at 5 meters.
> >A newspaper open on a table can be read from orbit. 
> 
> I strongly doubt the part about reading the newspaper from orbit.  I
> don't doubt that the pattern of text and pictures on the  front page
> could be identified from orbit. ('Identifying the difference between
> Pravda and Izvestia'.)   An approximation I once heard is that a lens or
> mirror of about 4.5 inch in diameter can resolve an angle of one
> arc-second.  A mirror of the size of the Hubble Space Telescope (which I
> assume approximates that of the typical spy satellite today) is about 20x
> larger, so the resolution should be 20x better, or 1/20 arc-second. 
> That's 1/(57 degrees per radian)(3600arcseconds per degree)(20) =
> 1/4,100,000 radian.  From an altitude of 500 kilometers, that's about 1/8
> of a meter, or 120 millimeter.  Maybe that's a pixel-pair, but it's far
> too large to resolve the text on a newspaper.  
> 
> The best prospect to improve on this resolution would be to use a
> 'multiple-mirror-telescope' technology.  Light-gathering capability isn't
> important in this application; high resolution is.  Making a
> spy-telescope out of a few different mirrors, held precisely many meters
> apart, could conceivable achieve resolutions substantially greater than
> this.
>         Jim Bell