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Comment by sho_hn | Hacker News Reader

There was. Sort of.

https://en.wikipedia.org/wiki/KH-11_KENNEN

In particular some of the manufacturing tooling for the mirrors were shared, leading to the HST mirror being downsized to 2.4 meters.

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Its surprising how many people don't know this all these years later. Hubble is repurposed spy satellite. The main cost of the vehicle isn't in the spacecraft itself though its the optics which are different from those used on KH-11. What is good for looking at Russian military bases doesn't directly translate to looking at galaxies.

In fact, the NRO donated two Hubble-like KH-11s in 2012, on the condition that they not be used to observe Earth.

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

One of them forms the base of https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telesc....

The person or persons, at the NRO or whatever other clandestine agency, who championed this donation, over what must have been very considerable hand-wringing about the consequences of giving this technology to civilians, are very fine people.

The story from the astronomy side was that the 2.4 meter mirror was mysteriously inexpensive compared to anything else in the R^2 mirror cost curve.

It's a little odd how people re-tell that story, but ok.

The techniques and tooling can be fit for both purposes but the telescope you build to look at something 250km away at high resolution and illuminated by the sun and the one you build to look at galaxies thousands of light years away that are fainter than can be seen with the naked eye are very very different.

Hubble's optics also weren't easy to produce and notoriously were faulty which had to be later corrected in orbit with a Shuttle mission. The bid being lower than expected could just as easily be explained by the contractor massively under bidding to win the contract. I've never heard anyone claim the Perkin-Elmer also made the optics for the KH series before now. Its not outside the realm of possibility but unless you have some compelling proof then I have no reason to believe that. I think the fact they screwed up indicates they probably weren't because if they had done the optics for the KH-11 series then they would have been well practiced at making mirrors that size by the time Hubble was built.

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