In July 1958, an astronomer at the University of Wisconsin–Madison named Arthur “Art” Code received a telegram from the fledgling Space Science Board of the National Academy of Sciences. The agency wanted to know what he and his colleagues would do if given the opportunity to launch into Earth’s orbit an instrument weighing up to 100 pounds. Code, newly-minted director of the University’s Washburn Observatory, had something in mind. Fifty years ago, on December 7, 1968, that idea culminated in NASA’s launch of the first successful space-based observatory: the Orbiting Astronomical Observatory, or OAO-2.