My favorite KH-11/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.