SPACE LAUNCH VEHICLESMany of the rockets that opened the space age were straightforward adaptations of ballistic missiles
to which upper stages were added to give the higher speeds necessary to achieve Earth orbit or to project payloads on lunar and interplanetary missions. The first Sputniks, as well as the Soviet manned spacecraft, were
launched by
rockets adapted from a Soviet ICBM with the NATO code name Sapwood. Even the powerful Soviet Proton rocket, first introduced in 1965 and ultimately used to launch the Salyut space station, embodied a good deal of military technology. In the United States the Juno I rocket that launched the first Explorer was developed from the army's Jupiter C rocket, which in turn was a successor of the Redstone. The Thor IRBM was used in combination with Able, Agena, and Delta stages. A modified Atlas ICBM was used to launch the four manned Mercury orbital flights and was later combined with Agena and Centaur stages for heavier payloads. The Titan ICBM was developed for use in the manned Gemini program and a variety of other missions.In addition, the National Aeronautics and Space Administration (NASA) developed or contracted for new launch vehicles, including the Delta, Scout, and Saturn rockets. Delta, the first rocket to be built specifically for NASA, was developed by the Douglas Aircraft Company and grew into a large family of vehicles that has provided launch reliability since 1960. Scout, the first rocket developed by NASA itself, also became operational in 1960 and was a low-cost means of launching lighter payloads. The Saturn I rocket, conceived by Wernher von Braun in 1958, was first launched with all stages operational in January 1964. After a number of interim improvements in the Saturn I, the Saturn V rocket was developed. Test-launched in 1967 and 1968, it performed flawlessly in the Apollo program.With the growth of space exploration and its commercial applications, a number of countries have developed their own launch capability. The European Space Agency's Ariane became a leader in the 1980s in the international competition for launching satellites; other such rockets include France's Diamant and Japan's H-1 (see space programs, national). Private firms such as Space Services, Inc., of the United States have been developing their own rocket fleetsÑfor example, Space Service's Conestoga booster for small payloads. The concept of employing reusable rockets instead of expendables such as the above was explored in the early 1980s by the U.S. Space Shuttle program, with its recoverable solid-propellant boosters and craft. The craft demonstrated its abilities in satellite launch and repair, but even before the 1986 Challenger disaster the concept of reusable rocketsÑas designed thus farÑhad been found far less economical in fact than that of expendables. Nevertheless Germany, France, Great Britain, Russia, and Japan have all pursued shuttle-type plans in addition to their other programs.