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Comment by pcunite | Hacker News Reader

I hold the understanding that its possible to view a license plate from space. I suggest you keep to that view in mind as well.

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The resolution of this satellite is about 5-7 cm per pixel which is about the limit of what's possible with the 2.4m mirror it uses. You'd need a mirror at least 10x as large to read license plates, and that's if they were pointing upward.

There are certainly no 20-30m telescopes in space (Also, imagine how annoyed astronomers would be if they found out the biggest most advanced space telescope in history was in space and pointing down...).

I do wonder what would be possible to resolve using multiple 2.4m scopes to create a larger synthetic aperture?

Resolving text on a license plate which would be at a very oblique angle (so more atmosphere) is probably not worth trying.

You don’t need multiple to get improvement in one dimension: it’s moving.

For something that will hold very still, you can wait for the next pass and synthesize.

> * imagine how annoyed astronomers would be if they found out the biggest most advanced space telescope in history was in space and pointing down*

Well, rumor is that Hubble was just a repurposed spy telescope, so astronomers probably should be annoyed :)

Annoyed? Sure. Surprised? Only the naive would be.

If there was a 3-5m spy satellite I wouldn't be surprised, but if there was a 20-30m spy satellite (I.e. a project likely larger in scale and complexity than the ISS) then I'd be surprised.

But we followed the making of hubble long before it launched. Why would anyone believe such a silly rumor when the development of the telescope was in the open?

What makes it a rumor? In the video Scott states that the “cost saving measure” of reducing the target mirror diameter down to 2.4m was to use the same manufacturing as these exact spy satellites.

Do you not understand that if a top secret spy satellite is gifted to astronomers, a cover story - i.e. a lie - will be made up about how it is developed by brilliant civilians?

Likewise it should be understood that the more complicated the coverup and the more detailed the lies, the more likely that cover story is to fall apart.

Given the cooperation with the ESA and with the difficulties in grinding the main mirror, I find it far less likely that it was a platform gifted to NASA by an intelligence agency.

I understand you believe that but I don’t have to believe it myself and that kind of condescending tone isn’t really necessary here, especially defending a conspiracy theory. The existing publicized NRO grants, including the keyhole satellites mentioned elsewhere in the thread, suggest the simpler answer is more accurate. The Hubble development was heavily publicized through its lifecycle, including the repair after it was deployed. Why bother with such a performance when next time the NRO donates a satellite they publish about it for the PR?

You would need thousands of civilians to take part in your life then. Not easy.

Hubble wasn't but a pair of Key Hole satellites (KH-11) were.

https://www.americaspace.com/2012/06/06/top-secret-kh-11-spy...

Hubble was built by the same contractors that build the Keyhole satellites. They whole idea from the beginning was to reuse the spy satellite hardware for astronomy.

Almost everything is reusable between these applications, just need a flatter mirror. Which was also what they screwed up.

>Also, imagine how annoyed astronomers would be if they found out the biggest most advanced space telescope in history was in space and pointing down

NASA's under-development WFIRST telescope is being built using old outdated hardware that the NRO didn't want any more.

https://en.wikipedia.org/wiki/2012_National_Reconnaissance_O...

Perhaps worth noting, there are certainly telescopes of this scale in space--they're just radio telescopes, where the reflector can conveniently be unfurled after launch.

You can glance at this thread [0] for comparison of commercial and speculated military antenna scales (up to 100m!)

[0] https://space.stackexchange.com/questions/32884/what-is-the-...

This is anecdotal, and no idea how real it is, but my dad flew reconnaissance for the USAF in the 70s and claimed to have the capability to read license plates way back then from very high altitude (no idea what qualified as very high altitude, but assumed they were not easily detected from the ground).

Let's do some napkin math. A quick websearch suggests spy sats orbit around 200-800km, while U2 flies at 20km.

Let's say you can use the same camera system on both. Then 10cm resolution at 200km orbit means 1cm at 20km, which would be enough to read a license plate.

You can't put a 2.4m mirror on a U2.

I believe the SR-71 had cameras that could resolve even more detail than license plates.

Edit: seems that I’m wrong. 6” ground resolution

I'm of the understanding that this was not a single image, but a composite image, taking by different satellites, planes, and/or drones.

The US could have build test facilities in their deserts, have a 3-D model available for proper reconstruction, and then learn to stitch and skew back all imagery into a single composite image. There may even be some "filling in" or "sharpening" of pixels or textures that could not be observed, but are guessed from their context.

In the framework of composite imagery, it would indeed be possible to zoom in, until you get to camera's capturing road traffic (maybe the license plate was not observed in the moment the main photo was taken, but was remembered from an observation by traffic camera 30 minutes ago and stitched back onto the object: composite imagery through time).

Finally, you could use multiple non-image sources for the composition. If three (ground) sensors capture the noise, heat, or vibrations from a train on a train track, you can now triangulate and draw the location of that train on space photos at a timestamp of your choosing.

Why do you believe it's a composite image?

> the license plate was not observed in the moment the main photo was taken

I believe there's a limit on resolution of a space satellite. If you're suggesting the traffic cam reads the plate, how are you going to connect the coloured blob that is the car with an image taken by a traffic cam at a different time in a country that doesn't give you access to its traffic cams?

> Why do you believe it's a composite image?

Because it is common to reconstruct a signal by taking multiple measurements, instead of a single sample. The field of compressed sensing broke ground on effective sampling. If (some) error is random noise, then you can remove this by majority vote. It is ineffective not to re-use that high-resolution secret drone fly-over footage, when composing satellite imagery at a later date. Inpainting, upscaling, de-oldifying, automatic coloring, 3D modeling, composition (see black hole photo process) etc. have become common usage in the ML community, and so I have reason to assume these techniques are also used to enhance and improve the resolution and unobserved guesstimates of satellite imagery.

> how are you going to connect the coloured blob that is the car with an image taken by a traffic cam at a different time in a country that doesn't give you access to its traffic cams?

Install road-side pointing camera's inside rented housing / contracted freedom fighter homes? Hack the traffic cams?

Didn't the NSA track mobiles in foreign countries by installing similar beacons / hacking sensors in bigger cities? That would theoretically allow them to view through the car roof and "see" who is in the backseat.

> The spy agency is said to be tracking the movements of “at least hundreds of millions of devices” in what amounts to a staggeringly powerful surveillance tool. It means the NSA can, through mobile phones, track individuals anywhere they travel – including into private homes – or retrace previously traveled journeys.

> The NSA provided some input into the report, with one senior collection manager, granted permission to speak to the newspaper, admitting the agency is “getting vast volumes” of location data from around the planet by tapping into cables that connect mobile networks globally.

> According to the Post, the NSA is applying sophisticated mathematical techniques to map cell phone owners’ relationships, overlapping their patterns of movement with thousands or millions of other users who cross their paths.

Maybe mixed terminology, to me a composite pic is one where sections or entireties of several pics have been arranged to make a larger or more detailed one. What you desrcibe is different, but ISWYM.

> Install road-side pointing camera's inside rented housing / contracted freedom fighter homes? Hack the traffic cams?

perhaps, sounds a bit james bondish though :)

The author of James Bond, Ian Flemming, worked as a commander for British Naval Intelligence, an officer for the 30 Assault Unit, whose task it was to gather intelligence behind enemy lines. His brother worked with "stay-behind" freedom fighter networks. :)

https://en.wikipedia.org/wiki/Operation_Ruthless

I did not know that.

Fair swap, graham greene was also a spay[0] https://en.wikipedia.org/wiki/Graham_Greene#Travel_and_espio...

[0] typo, but I rather like that one.

Viewing a license place it not the same as reading it.

Yes, but if there is video instead of a still frame, it may be possible to put together what the characters on the plate are.

Not with that resolution (7cm / pixel).

We know what can be written on license plates, and we know that license plates don't change over short times, so it's possible to determine which characters best match the sequence of frames even if no individual frame is readable. See: https://en.wikipedia.org/wiki/Super-resolution_imaging

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