U.S. Space-Launch Vehicle Technology: Viking to Space Shuttle

3. The Atlas Space-Launch Vehicle and Its Upper Stages, 1958–1990

3 The Atlas Space-Launch Vehicle and Its Upper Stages, 1958–1990 Even before it began its service as a missile, the Atlas had started to function as a space-launch vehicle. In December 1958 as part of Project Score, an entire Atlas (less its two jettisoned booster engines) went into temporary orbit carrying a repeater satellite that could receive messages from Earth and send them back. Then, simultaneously with their role in Project Mercury, modified Atlas missiles began to serve as space-launch vehicles for both the Air Force and NASA in a variety of missions. For this purpose, the basic Atlas was standardized, uprated, lengthened, and otherwise modified in a variety of configurations that were often individually tailored for specific missions. Engineers mated the vehicle with a number of different upper stages, of which the Agena and Centaur were the best known and most important. In these various configurations, Atlas space boosters launched satellites and spacecraft for such programs as Samos, Midas, Ranger, Mariner, Pioneer, Intelsat , the Fleet Satellite Communications System, the Defense Meteorological Satellite Program, and the Navstar Global Positioning System. Following the end of the period covered in this book (roughly 1990), some Atlases even used strap-on solid motors to supplement their thrust at liftoff.1 Most of the upper stages used with Atlas were derivatives of other programs . This was true of both the liquid-propellant Agena and a variety of solid-propellant upper stages. The Centaur, however, was in a sense a derivative of Atlas, in that it used the steel-balloon tank structure envisioned by Charlie Bossart and developed for the Atlas missile. Nevertheless, adapting that structure to liquid hydrogen fuel proved to be a major challenge that required a great deal of cut-and-try engineering as well as a major reorganization of the way Centaur was managed. Still, after initial delays, the Centaur worked and went on to contribute technology to the Saturn upper stages and to the space shuttle. U.S. Space-Launch Vehicle Technology 84 Project Score The Advanced Research Projects Agency was the sponsor of Project Score (Signal Communications by Orbiting Relay Equipment), in which a B-model Atlas zoomed into orbit on December 18, 1958, controlled by a General Electric radio-inertial guidance system. Fewer than a hundred people were let in on the secret that the missile was being orbited with 150 pounds of communications relay equipment, although many employees at Cape Canaveral had their suspicions because of deviations from the normal pattern for missile test flights. Two hours after the tank section of the missile was in low Earth orbit, President Eisenhower announced that the United States had orbited an object weighing some 8,800 pounds. (The main section of the Atlas weighed almost 8,700 pounds; pods installed by the Army Signal Corps along the missile’s side carried the 150 pounds of communications equipment.) Among the transmissions from the satellite was a Christmas message recorded by the president. Reportedly, this was the first time a human voice had been broadcast from space. The satellite also relayed messages transmitted from ground stations in Georgia, Arizona, and Texas. Expected to stay in space only twenty days, the vehicle and its equipment remained in orbit for more than a month before reentering the atmosphere on January 21, 1959, and burning up over the Pacific Ocean near Midway Island . While the Soviets’ Sputnik 3, launched on May 15, 1958, had weighed an impressive 2,925 pounds, the Project Score satellite almost tripled that weight.2 Atlas-Able There were three attempts to launch Atlases mated with Able upper stages.3 These efforts were outgrowths of the Thor-Able lunar probes and employed similar hardware and instrumentation in the upper stages. Stimulated by a Space Technology Laboratories (STL) proposal to the Advanced Research Projects Agency in June 1958, NASA conceived the project in November of that year, initially to place a probe in a Venus orbit. The new space agency worked with the Ballistic Missile Division (BMD) and STL to obtain the launch vehicles, with BMD responsible for conducting the program under NASA’s overall management. By June 1959 if not before, NASA had decided on a somewhat less ambitious lunar-orbiting payload. Atlas’s thrust, greater than Thor’s, allowed a heavier and more sophisticated satellite to be launched into an orbit around the Moon. It weighed 362.5 pounds, about The Atlas Space...