The Hubble Space Telescope launched in April 1990 with huge expectations, and two months later NASA had to admit the images were blurry. The main mirror had been ground to the wrong shape, too flat near its outer edge, with an error ten times larger than allowed. It was an embarrassing mistake. Instead of giving up, engineers designed corrective optics, and in December 1993 astronauts flew up and installed what amounted to a pair of eyeglasses for Hubble. The before and after pictures were stunning. The telescope that started as a punchline went on to give us some of the most beautiful views of the universe ever seen.
