> In the 80s, 30+ years ago, license plates were discernible from orbit.
This is absolutely false.
This is absolutely false.
It was also known by the likes of William Safire that our satellites could "read the license plates on the cars of Kremlin officials."
--
If untrue, please provide a counter source to many of the like statements as cited above. (You may be right, but it seems that many believe you are wrong)
Under 'twenty questions', second column, end of column, under highlights "Big Bird" satellite.
Again, you may be right. However there are many claims that this capability existed in the 80s.
Suggest you research some of the satellites of the time, including ones which worked on film, and jettisoned rolls of it for terrestrial pickup.
I wouldn't be surprised if they could do that but there was no proof around to demonstrate it. The military tend to be very secretive about what they can do because by revealing it they would implicitly give hints on what they cannot do.
Suggest you do the same.
Here's the "Big Bird" satellite you referred to: https://en.m.wikipedia.org/wiki/KH-9_Hexagon
> The cameras could scan contiguous areas up to 120 degrees wide, and achieved a ground resolution better than 2 ft (0.61 m) during the later phase of the project.
The sources you cite are, to put it nicely, propaganda. The physics simply doesn't agree that this was even remotely possible at the time.
Another commenter correctly pointed out that these claims would violate the diffraction limit by more than an order of magnitude, and that's assuming zero atmospheric interference, which is absolutely not the case.
Why do you think film is relevant here? These satellites are not noise-limited like your phone vs. an SLR, they're diffraction limited. This is an optical resolution limit that has nothing to do with the photon capture medium or the size of the photographic plate. The only way to do better is to increase the effective area (of the mirror, not the plate) or to decrease the effective wavelength.
They were not doing interferometry with these satellites, and certainly not the multi-axis interferometry you'd need to be able to resolve centimeter-thick lines in text.
Yet this comment was refuted, and you have not addressed that fully.
> Why do you think film is relevant here?
As per the timeline, my comment with the film reference was written prior to any discussion about noise, or diffraction.
It was simply there to demonstrate the lengths gone, 2 decades prior to the 80s, in the 60s, to get imagery back to Earth.
I was curious how they did it in the early days, as video transmission technology was nascent. It quite certainly would have been a potential massive blocker on quality, from satellite to surface. Film seemed to solve that aspect of things in those early days.
I found this highly interesting. Film, from multiple lenses, the ultimate sneaker net (yes, it's analog, but still...)
Anyhow, over the years I've seen so many technical issues overcome, with sideways attacks on the problem. When people start saying "But... impossible!", I tend to have a high degree of skepticism.
I will say this though. Yes, it certainly could have been propaganda.
Doesn't mean it was, but I certainly do agree the potential is there.
I'll say two things here.
First, I'll still say "post film manipulation and processing may have enhanced imagery, and they were constantly modifying this gear from what I've read in that PDF."
Second, "Big Bird" was decommissioned in the mid 80s.
https://www.thespacereview.com/article/3662/1
There's no way it wasn't replaced with something else. What was that?
An example, is the https://en.wikipedia.org/wiki/KH-11_Kennen system, which wikipedia says was launched in the 70s, has multiple iterations, and is still being used.
https://en.wikipedia.org/wiki/KH-11_Kennen#Imaging_sensors_a...
Shows some of these versions, and blockIII seems to have very nice resolution. Launched in 92, supposedly.
And yet, as these all of the programs? I doubt it. For example "Big Bird" (KH-9) and KH-11 were used in parallel. I bet others existed too.
I'm going to say that throwing out "No, it couldn't be done" in the 80s is hard for me to believe. Was it done?
Well if not, it was very close to the 80s, as in the very early 90s.
l = 1.22 * λ * L / D
Where λ is wavelength, L is distance and D is optical element diameter.
For satellite at an altitude of 150 km with 2.4 m diameter mirror and 0.4 μm blue light, this gives a spatial resolution of 0.3 m. To read a number plate requires an order of magnitude better than this.
To anyone reading this:
Pages 100 onward, you get to see diagrams of how it was built, and pics of the retrieval system and info on methods.
Page 120 onward talks about that return unit in more detail.
Page 122 I found interesting, details about measures to prevent the return unit from falling into enemy hands.
Page 128 is a good summary image, with some details on the lower right.
Page 165 onward, especially 168 have actual shots. 168 looks better than the first Google Earth images, and you can easily make out and identify how many 'things' the enemy has.
Sadly I have no more time currently to read, and more sadly some details are still redacted. Understandable, when I ponder the nature of some of those redacted parts. EG, privacy, current contractors still employed, tech methods still used on newer gear, at time of declassification.