NASA SP-2004-4230. NASA History Series. Chronicles the story of the Centaur, the world's first liquid-hydrogen rocket. Focuses on technical and political hurdles that Centaur faced over the three decades that it was managed by NASA Lewis Research Center. Explores NASA's effort to modify Centaur for launch from the Shuttle's cargo bay, a controversial project canceled in the wake of the Challenger accident.

During its maiden voyage in May 1962, a Centaur upper stage rocket, mated to an Atlas booster, exploded 54 seconds after launch, engulfing the rocket in a huge fireball. Investigation revealed that Centaur's light, stainless-steel tank had split open, spilling its liquid-hydrogen fuel down its sides, where the flame of the rocket exhaust immediately ignited it. Coming less than a year after President Kennedy had made landing human beings on the Moon a national priority, the loss of Centaur was regarded as a serious setback for the National Aeronautics and Space Administration (NASA). During the failure investigation, Homer Newell, Director of Space Sciences, ruefully declared: "Taming liquid hydrogen to the point where expensive operational space missions can be committed to it has turned out to be more difficult than anyone supposed at the outset." .After this failure, Centaur critics, led by Wernher von Braun, mounted a campaign to cancel the program. In addition to the unknowns associated with liquid hydrogen, he objected to the unusual design of Centaur. Like the Atlas rocket, Centaur depended on pressure to keep its paper thin, stainless-steel shell from collapsing. It was literally inflated with its propellants like a football or balloon and needed no internal structure to give it added strength and stability. The so-called "pressure-stabilized structure" of Centaur, coupled with the light weight of its high-energy cryogenic propellants, made Centaur lighter and more powerful than upper stages that used conventional fuel. But, the critics argued, it would never become the reliable rocket that the United States needed. Others, especially military proponents of Centaur, believed that accepting the challenge of developing liquid-hydrogen technology was an important risk to take. Despite criticism and early technical failures, the taming of liquid hydrogen proved to be one of NASA's most significant technical accomplishments. Centaur not only succeeded in demonstrating the feasibility of liquid hydrogen as a rocket fuel, but it also went on to a brilliant career as an upper stage for a series of spectacular planetary missions in the 1970s. Ironically, this success did little to ensure the future of the Centaur rocket. Once the Shuttle became operational in the early 1980s, all expendable launch vehicles like Centaur were slated for termination. Centaur advocates fought to keep the program alive.

The story of how liquid hydrogen was put to work is told in two great books. Part 1 is this book, "Liquid Hydrogen as a Propulsion Fuel, 1945-1959", by John L. Sloop (NASA SP-4404). Part 2 is "Taming Liquid Hydrogen: The Centaur Upper Stage Rocket: 1958-2002", by Virginia P. Dawson and Mark D. Bowles (NASA SP-2004-4230).

On 29 July 1958, President Dwight D. Eisenhower signed the National Aeronautics and Space Act, creating the National Aeronautics and Space Administration (NASA), which became operational on 1 October of that year. Over the next 50 years, NASA achieved a set of spectacular feats, ranging from advancing the well-established field of aeronautics to pioneering the new fields of Earth and space science and human spaceflight. In the midst of the geopolitical context of the Cold War, 12 Americans walked on the Moon, arriving in peace “for all mankind.” Humans saw their home planet from a new perspective, with unforgettable Apollo images of Earthrise and the “Blue Marble,” as well as the “pale blue dot” from the edge of the solar system. A flotilla of spacecraft has studied Earth, while other spacecraft have probed the depths of the solar system and the universe beyond. In the 1980s, the evolution of aeronautics gave us the first winged human spacecraft, the Space Shuttle, and the International Space Station stands as a symbol of human cooperation in space as well as a possible way station to the stars. With the Apollo fire and two Space Shuttle accidents, NASA has also seen the depths of tragedy. In this volume, a wide array of scholars turn a critical eye toward NASA’s first 50 years, probing an institution widely seen as the premier agency for exploration in the world, carrying on a long tradition of exploration by the United States and the human species in general. Fifty years after its founding, NASA finds itself at a crossroads that historical perspectives can only help to illuminate.