Page:This New Ocean, a history of Project Mercury, Swenson, Grimwood, Alexander (NASA SP-4201).djvu/35

Launch of the record-setting U.S. Army-Jet Propulsion Laboratory Bumper WAC (V-2 first stage and WAC/Corporal second stage) from White Sands Proving Ground, N. Mex. The first Bumper-WAC launch occurred on May 13, 1948. On February 24, 1949, the two-stage rocket reached its record altitude of 244 miles and speed of 5150 miles per hour.

tion 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