Space telescope to maintain. The Hubble Space Telescope was serviced by the Space Shuttle while many other space telescopes cannot be serviced at all. Space observatories can generally be divided into two classes: missions which map the entire sky (surveys), and observatories which focus on selected astronomical objects or parts of the sky. Satellites have been launched and operated by NASA, ISRO, ESA, Japanese Space Agency and the Soviet space program later succeeded by Roskosmos of Russia. As of 2018, many space observatories have already completed their missions, while others continue operating on extended time. However, the availability of space telescopes and
Space Shuttle program shuttle design that best balanced capability, development cost and operating cost. Ultimately chosen was a design using a reusable winged orbiter, reusable solid rocket boosters, and an expendable external fuel tank for the orbiter's main engines. The shuttle program was formally launched on January 5, 1972, when President Nixon announced that NASA would proceed with the development of a reusable space shuttle system. The stated goals of "transforming the space frontier...into familiar territory, easily accessible for human endeavor" was to be achieved by launching as many as 50 missions per year, with hopes of driving down per-mission costs. The prime