Thread

1. Almondsetat · 1790809198 · focus · HN ↗

   The incredible and futuristic technologies the US managed to deploy decades before the competition reminds me of the story of how the NRO gifted NASA a couple of their old decommissioned satellites in 2012 and they turned out to be basically upgraded Hubble telescopes pointed at earth. The US from the 90s to the 2000s had multiple Hubble-level telescopes just for spying while NASA was fighting for scraps to study the entire cosmos.

   1. monocasa · 1790813494 · focus · HN ↗

      Way longer than that. The first KH-11 satellites that Hubble shares its design with were in orbit in the late 1970s.

      <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;KH-11_KENNEN" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;KH-11_KENNEN

      1. palmotea · 1790830542 · focus · HN ↗

         &gt; Way longer than that. The first KH-11 satellites that Hubble shares its design with were in orbit in the late 1970s.

         I&#x27;m not sure if it actually &quot;shares its design&quot; with KH-11, but has a more indirect connection, e.g.:

         <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=23150092">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=23150092:

         &gt; My favorite KH-11&#x2F;Hubble story is that during the design of the Hubble Space Telescope, NASA originally wanted a 3 meter mirror. However when they began to design and budget the satellite they were quietly told they should reconsider and use a 2.4 meter mirror, as this would be significantly cheaper since they would be able to leverage existed machinery capable of created mirrors of that size and precision. That infrastructure and manufacturing process had already been created a decade earlier for Keyhole.

         1. voidUpdate · 1790849249 · focus · HN ↗

            If the manufacturing for the 2.4 meter mirrors existed a decade earlier, and Hubble used the existing processes, does that mean all the KH-11 satellites also have the spherical aberration problem that Hubble has?

            1. scrlk · 1790857594 · focus · HN ↗

               The spherical aberration of Hubble&#x27;s main mirror was caused by a manufacturing defect.

               Perkin-Elmer designed a new null corrector to verify that the mirror was made to spec, but the null corrector was incorrectly assembled (one of the lenses was out by a few mm). They also used the previous null corrector to test, which showed that the mirror was incorrectly ground, but decided that the new null corrector&#x27;s measurements was correct.

               1. voidUpdate · 1790858602 · focus · HN ↗

                  But wouldn&#x27;t they have needed to do that for KH satellites too? If they&#x27;re making new equipment and processes, they&#x27;ll be saving a lot less money from using KH mirrors

                  1. rtkwe · 1790870968 · focus · HN ↗

                     It was a new piece of test&#x2F;validation equipment used on Hubble first. Reread it, they used the new equipment to test Hubble that had an error during assembly, they also crosschecked against the old machine which showed the mirror was flawed, and incorrectly decided that the newer machine was correct when it passed the Hubble mirror.

                     The test equipment is a much smaller part of the cost than developing, building and testing the machines required to actually grind the mirrors to spec in the first place.

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