Project Orion: The True Story of the Atomic Spaceship ,

Henry Holt
New York
, 2002. $26.00 (345 pp.). ISBN 0-8050-5985-7

On 4 October 1957, the Soviet Union surprised the world by launching Sputnik. We are fortunate to have George Dyson’s beautiful account of an episode that captures the spirit of America’s successful response to this challenge. Project Orion—a proposed nuclear-energy-based space propulsion system—was never allowed to progress to any meaningful test. However, Dyson’s portrayal of the boldness of the concept and the enthusiasm of the scientists involved provides a deeper insight into the latent power of an aroused free society than the histories of successful but less imaginative projects.

Chemically fueled rockets, with their low energies per unit volume, require two or three stages, with costs currently about $10 000 per kg of pay-load, to achieve low Earth orbit. Thus chemical rockets have been practical only when payloads have great economic or political value per unit weight. That restriction inspired several attempts to use nuclear energy for propulsion. One of the more imaginative suggestions was Stan Ulam’s: that a small nuclear explosion at an appropriate distance from a space vehicle could vaporize a renewable surface layer on a “pusher plate,” and thus could be used for propulsion. Since the evaporated material would be heated to temperatures much higher than are attainable from chemical reactions, much higher propellant velocities could be achieved. Repeated small nuclear explosions would enable high spacecraft velocities. The availability of higher propellant velocities would release designers from the severe restrictions and high costs of the chemically powered space program. The Solar System could be explored with manned round-trip voyages.

Project Orion was organized in 1958, on the heels of Sputnik, to realize these possibilities. Ted Taylor, Freeman Dyson, and many other distinguished scientists devoted themselves to Orion for years. The Defense Department’s Advanced Research Projects Administration (ARPA), by far the most imaginative of the government’s supporters of research, financed the start of Orion with a $1 million feasibility study.

George Dyson, Freeman’s son, reproduces many of his father’s letters to his parents, which, although limited to unclassified material, convey much of the excitement of this creative project. Freeman retained his enthusiasm for Orion until 1959, when he convinced himself that the radioactive byproducts deposited in the atmosphere and the magnetosphere might result in about one more cancer per mission in Earth’s population. He considered this cost too high. The others carried on with somewhat reduced enthusiasm.

The critical time for project Orion came at about the time of John F. Kennedy’s election to the presidency in 1960. NASA had rejected Orion, saying “It would be extremely difficult to divert funds from nearer-term projects for the support of Orion. We would not therefore, favor any arrangement requiring such support.” ARPA turned to the US Air Force, which found that it could squeeze Orion in, despite the ordinary restriction of the air force to projects meeting military requirements. Taylor and the other Orion scientists managed to keep the project sputtering along until 1965.

The late Trevor Gardiner, assistant secretary of the air force, headed a committee (of which I was a member) formed to propose a response to Sputnik. That committee issued an unclassified report in March 1961, saying that “nuclear propulsion may more than double the specific impulse attainable while still maintaining high thrust-to-weight ratios and could make possible the utilization and exploration of space on a truly vast scale.”

Vice President Lyndon Johnson controlled all space matters; the unclassified Gardiner Committee report apparently did not fit his plans. He declared it “Top Secret” and ordered all the copies to be kept in his safe. This action squelched all but the space initiatives that were to be located in the states of LBJ’s Deep South constituency. I repeatedly requested the release of the Gardiner report under the Freedom of Information Act, and finally was successful in 1995. In addition to nuclear energy proposals, the items suppressed included Earth-orbital assembly schemes using available chemical rockets (similar to the suggestion by Taylor et al., which Dyson describes on p. 218). I have no doubt that those proposals would have fulfilled Kennedy’s moon landing commitment sooner and more cheaply than the plan LBJ approved. But even more important, they would have given us a much more exciting space program.