Rockets

ROCKETS

ROCKETS. In their most basic form, rockets are uncomplicated machines. They comprise a fuel supply, a combustion chamber in which the fuel is burnt, and a nozzle through which the products of combustion—mostly hot gasses—can escape. Early rockets were little more than tubes closed at one end and filled with gunpowder. They were used for fireworks and for maritime rescue (as signals and carriers of lifelines), but they lacked the power and accuracy to be useful beyond these highly specialized niches. Military interest in gunpowder rockets was sporadic and limited. The British use of them to bombard Fort McHenry, near Baltimore during the War of 1812, for example, did more for American culture (by inspiring Francis Scott Key to write "The Star Spangled Banner") than it did for British military objectives.

Modern rockets emerged between 1920 and 1960 from the confluence of several technological breakthroughs:

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more powerful fuels, lighter structural elements, steering mechanisms, onboard guidance systems, and multiple stages. These changes set the stage for the rocket's development, from the late 1950s on, into a range of powerful weapons and a versatile tool for scientific exploration.

The Birth of Modern Rocketry, 1920–1960

Robert H. Goddard was the spiritual father but not the true founder of American rocketry. He tested his first solid-fuel rocket on 7 November 1918 and the world's first liquid-fueled rocket (burning gasoline and liquid oxygen) on 16 March 1926. Trained as a physicist, Goddard produced rockets notable more for innovative design features than for sound engineering. He also feared that rivals might steal his ideas—an obsession that led him to publish few papers and keep potential collaborators at arm's length. His genius was prodigious, but his influence was slight.

The foundations of American rocketry were laid, in a practical sense, by four small groups of scientists and engineers scattered across the country. The first of these groups, the American Rocket Society, was formed as the American Interplanetary Society in 1930 by a group of technically minded New York City science fiction writers (they renamed their group in 1934). Its leading members went on to found Reaction Motors, one of America's first rocket-building companies. A second important group coalesced in the late 1930s around aerodynamics expert Theodore von Karman at the California Institute of Technology(Cal Tech). In time this group gave rise to another early rocket-building firm: Aerojet. A third group, led by naval officer Robert Truax, formed in the late 1930s at the Naval Research Laboratory in Annapolis, Maryland. The fourth group consisted of 115 scientists and engineers from Germany's wartime rocket program, led by the charismatic Wernher von Braun and hired by the U.S. Army to apply their expertise to its nascent rocket-building program. They brought with them boxes of technical documents and scores of V-2 rockets—then the world's most advanced—in various stages of assembly. Reassembling and test-firing the V-2s under the Germans' direction gave army rocket experts their first practical experience with large ballistic missiles.

All four groups worked closely with the military. Von Braun's and Truax's were directly supported by the army and navy, respectively. Von Karman worked closely with General Henry H. "Hap" Arnold, commander of the U. S. Army Air Forces. Reaction Motors supplied the engines for most of the Air Force's experimental rocket planes, including the Bell X-1 that broke the "sound barrier" in 1947. Through their military projects, the rocket designers also made connections with established defense contractors. The foundations of a robust aerospace industry had thus been laid even before the end of World War II.

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The rockets that emerged from these collaborations in the late 1940s and early 1950s established the basic design elements used by American rockets for the rest of the century. These included multiple stages (1947), lightweight aluminum rocket bodies that doubled as fuel tanks (1948), and swiveling engines for steering (1949). High-energy kerosene derivatives replaced gasoline and alcohol in liquid-fuel rockets. Research at Cal Tech produced a viscous solid fuel that produced more power and higher reliability than traditional powders. Thiokol Chemical Corporation improved it and by the 1950s had enabled solid-fuel rockets to match the power of liquid-fuel ones. Combined, these features created a new generation of rockets. The first representatives—such as the Vanguard and Jupiter of the late 1950s—carried the first small American satellites into space. Later examples—such as Atlas and Titan of the early 1960s—had the power to carry a nuclear warhead halfway around the world or put a manned spacecraft into orbit.

Refinements and Applications, 1960–2000

President John F. Kennedy's May 1961 call to land a man on the moon "before this decade is out" gave von Braun and his team—then working for the National Aeronautics and Space Administration (NASA)—a chance to develop the largest rockets in history. The result was the Saturn V, which made possible nine lunar missions (six of them landings) between December 1968 and December 1972. Taller than the Statue of Liberty and heavier than a navy destroyer, the Saturn V generated the equivalent of 180 million horsepower at the moment of liftoff. However, the Saturn series was a technological dead end. No branch of the military had a practical use for so large a rocket, and (without the spur of a presidential challenge) the civilian space program could not afford to use them for routine exploration. Experiments with nuclear-powered rockets, pursued in the mid-1960s, were discontinued for similar reasons.

Saturn was, therefore, a typical of American rocket development after 1960. Specialization, rather than a continual push for more power and heavier payloads, was the dominant trend. The navy, for example, developed the Polaris—a solid-fuel missile capable of being carried safely aboard submarines and launched underwater. The air force developed the Minuteman as a supplement to the Atlas and Titan. It was smaller, but (because it used solid fuel) easier to maintain and robust enough to be fired directly from underground "silos." All three armed services also developed compact solid-fuel missiles light enough to be carried by vehicles or even individual soldiers. Heat-seeking and radar-guided missiles had, by the Vietnam War (1964–1975), replaced guns as the principal weapon for air-to-air combat. They also emerged, in the course of that war, as the antiaircraft weapons most feared by combat pilots. Warships, after nearly four centuries serving principally as gun platforms, were redesigned as missile platforms in the 1960s and 1970s. "Wire-guided" missiles, first used in combat in October 1966, gave infantry units and army helicopter crews a combination of mobility, accuracy, and striking power once available only to tanks.

The space shuttle, NASA's followup to the Project Apollo moon landings, defined another line of rocket development. Conceived as a vehicle for cheap, reliable access to space, it was powered by three liquid-fuel engines aboard the winged orbiter and two large solid-fuel boosters jettisoned after launch. Both were designed to be reusable. The orbiter's engines would, according to the design specifications, be usable up to fifty times with only limited refurbishing between flights. The boosters, parachuted into the Atlantic Ocean after launch, would be cleaned, refurbished, and refilled with solid fuel for later reuse. By the early 2000s the shuttle, since becoming operational in 1981, had achieved neither the high flight rates nor the low costs its designers envisioned. Its reusability was, nonetheless, a significant achievement in a field where, for centuries, all rockets had been designed as disposable, single-use machines.

BIBLIOGRAPHY

Bromberg, Joan Lisa. NASA and the Space Industry. Baltimore: Johns Hopkins University Press, 1999. Surveys NASA's evolving partnership with aerospace companies.

Heppenheimer, T. A. Countdown: A History of Space Flight. New York: John Wiley, 1997. Places rocket development in its social, political, and military context.

Ley, Willy. Rockets, Missiles, and Men into Space. New York: Viking, 1968. Dated, but useful for its lucid explanations and insider's view of early rocketry.

MacDougall, Walter A. The Heavens and the Earth. New York: Basic Books, 1985. Definitive history of the interplay of Cold War politics, military missiles, and the U. S. space program.

Winter, Frank. Rockets into Space. Cambridge, Mass.: Harvard University Press, 1990. A compact, nontechnical history of rocket technology.

A. Bowdoin Van Riper

See also Missiles, Military ; National Aeronautics and Space Administration ; Space Program ; Space Shuttle .