I think it was the Hubble Space Telescope that they couldn't get to focus properly once it was in orbit. It turned out the mirror wasn't the correct dimensions due to some American inputting a measurement of something in imperial instead of SI units during the manufacture of the mirror. NASA being an international scientific sort of organisation had decreed that SI units must always be used. The upshot was that they had to send up a space shuttle and two astronauts had to do a space walk to fit an additional lens. It didn't cost much at all. 😊