The United States developed guided missiles for air-to-air, air-to-surface, and surface-to-air interception uses and as tactical surface-to-surface weapons. Rocket motors, using both liquid and solid fuels, gradually replaced jet propulsion systems, but short-range defensive missiles remained advanced enough for most tastes until the late 1950s.54
As for scientific research in the upper atmosphere, the backlog of V-2s put together by the United States Army from captured components would do in the early postwar years. From April 1946 to October 1951, 66 V-2s were fired at the Army's White Sands Proving Grounds, New Mexico, in the most extensive rocket and upper-atmospheric research program to that time. The Army Ordnance Department, the Air Force, the Air Force Cambridge Research Center, the General Electric Company, various scientific institutions, universities, and government agencies, and the Naval Research Laboratory participated in the White Sands V-2 program. Virtually all the rockets were heavily instrumented, and many of them carried plant life and animals. V-2s carried monkeys aloft on four occasions; telemetry data transmitted from the rockets showed no ill effects on the primates until each was killed in the crash. The most memorable launching at White Sands, however, came on February 24, 1949, when a V-2 boosted a WAC Corporal rocket developed by the Jet Propulsion Laboratory 244 miles into space and to a speed of 5,510 miles per hour, the greatest altitude and velocity yet attained by a man-made object. A year and a half later, a V-2 - WAC Corporal combination rose from Cape Canaveral, Florida, in the first launch at the Air Force's newly activated Long Range Proving Ground.55
By the late forties, with the supply of V-2s rapidly disappearing, work had begun on more reliable and efficient research rockets. The most durable of these indigenous projectiles proved to be the Aerobee, designed as a sounding rocket by the Applied Physics Laboratory of Johns Hopkins University and financed by the Office of Naval Research. With a peak altitude of about 80 miles, the Aerobee served as a reliable tool for upper-atmospheric research until the late 1950s.56 The Naval Research Laboratory designed the Viking, a long, slim high-altitude sounding rocket, manufactured by the Glenn L. Martin Company of Baltimore. In August 1951 the Viking bettered its own altitude record for a single-stage rocket, reaching 136 miles from a White Sands launch. In the fifties, instrumentation  carried in Aerobees and Vikings extended knowledge of the atmosphere to 150 miles, provided photographs of Earth's curvature and cloud cover, and gave some information on the Sun and cosmic radiation.57
In 1955 the Viking was chosen as the first stage and an improved Aerobee as the second stage for a new, three-stage rocket to be used in Project Vanguard, which was to orbit an instrumented research satellite as part of the American contribution to the International Geophysical Year. The decision to use the Viking and the "Aerobee-Hi" in this country's first effort to launch an unmanned scientific satellite illustrates the basic dichotomy in thought and practice governing postwar rocket development in the United States: After the expenditure of the V-2s, scientific activity should employ relatively inexpensive sounding rockets with small thrusts. Larger, higher-thrust, and more expensive rockets to be used as space launchers must await a specific military requirement. Such a policy meant that the Soviet Union, early fostering the ballistic missile as an intercontinental delivery system, might have a proven long-range rocket before the United States; the Soviets might also, if they chose, launch larger satellites sooner than this country.
By 1951, three sizable military rockets were under development in the United  States. One, an Air Force project for an intercontinental ramjet-booster rocket combination called the Navaho, took many twists and turns before ending in mid-1957. After 11 years and $680 million, the Air Force, lacking funds for further development, canceled the Navaho enterprise. Technologically, however, Navaho proved a worthwhile investment; its booster-engine configuration, for example, became the basic design later used in various rockets.58 The two other rocket projects being financed by the military in the early fifties were ultimately successful, both as weapons systems and as space boosters.
52 Among the air-breathing guided missiles (a term that simply meant any pilotless flying craft) designed and developed by the Navy and the Air Force in the first decade after the war were the Gorgon, Plover, Regulus, Cobra, Bomarc, Snark, Matador, and Loon, the last being a Navy version of the German V-1. Of these weapons only the Snark was a genuinely long-range, or intercontinental, missile, and it was subsonic and thus vulnerable to radar-controlled antiaircraft rockets. See Ordway and Wakeford, International Missile and Spacecraft Guide, 3-5, 8-9, 15-16, 20-24, 26, 61.
53 Quoted, among many other places, in Inquiry into Satellite and Missile Programs, Part I, 283. For a more lengthy argument against early attempts to develop intercontinental ballistic missiles, see Vannevar Bush, Modern Arms and Free Men (New York, 1949).
54 See Kenneth W. Gatland, Development of the Guided Missile (London, 1954); and Nels A. Parsons, Guided Missiles in War and Peace (Cambridge, Mass., 1956), and Missiles and the Revolution in Warfare (Cambridge, Mass., 1962).
55 On the postwar V-2 program at White Sands and Cape Canaveral, see U.S. Army Ordnance Corps/General Electric Co., Hermes Guided Missile Research and Development Project, 1944-1954 (Sept. 25, 1959), 1-4; Ley, Rockets, Missiles, and Space Travel, 254-271; Akens, Historical Origins of the Marshall Space Flight Center, 28-35; Ernest Krause, "High Altitude Research with V-2 Rockets," Proceedings of the American Philosophical Society, XCI (1947), 430-446; and J. Gordon Vaeth, 200 Miles Up: The Conquest of the Upper Air (2 ed., New York, 1956), 117-134. Unless otherwise indicated, all mileage figures used in this work refer to statute miles.
On Thanksgiving Day 1963, several months after Project Mercury officially ended, President Lyndon B. Johnson renamed Cape Canaveral, Cape Kennedy. Since that is beyond the historical context of this study, throughout the rest of this work Cape Canaveral will be used.
56 Ibid., 178-194; Homer E. Newell, Sounding Rockets (New York, 1959), 54-95; Emme, Aeronautics and Astronautics, 53-54, 58-59, 63,67,69-70, 77.
57 On the Viking see Ley, Rockets, Missiles, and Space Travel, 271-276; Milton Rosen, The Viking Rocket Story (New York, 1955); John P. Hagen, "The Viking and the Vanguard," in Emme, ed., History of Rocket Technology, 123-125; also published in Technology and Culture, IV (Fall 1963), 436—437; Vaeth, 200 Miles Up, 195-206; and Newell, Sounding Rockets, 235-242. The first Viking shot, fired in May 1950 from the deck of the Norton Sound in the Pacific, set a new single-stage altitude record, 106.6 miles.
58 On the Navaho see Ordway and Wakeford, International Missile and Spacecraft Guide, 9-10; and Emme, Aeronautics and Astronautics, 64, 70, 72, 74, 76, 77, 86. Besides booster development, the technological heritage from the Navaho program included the airframe for the Hound Dog air-to-surface missile, progress in using titanium for structures, and the guidance system for nuclear powered submarines.