Orbiting Astronomical Observatory Program

NASA’s Orbiting Astronomical Observatory Program developed four space observatories between 1966 and 1972 to demonstrate the scientific value of long-duration astronomy above Earth’s atmosphere. OAO-2, launched in 1968 and nicknamed Stargazer, became NASA’s first successful cosmic observatory, making the first orbital stellar observations in ultraviolet light and establishing a direct path toward Hubble and later space telescopes.