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Comment by vinaypai | Hacker News Reader

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.

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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-...

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