Monday, March 19, 2007

Project Orion


Project Orion was an advanced rocket design explored in the 1960s. Orion is also the name of NASA's new spacecraft for human space exploration, previously known as the Crew Exploration Vehicle, which is designed to replace the Space Shuttle and eventually return to the Moon. For details of the Orion Crew Exploration Vehicle, go here.

The 1960s Project Orion examined the feasibility of building a nuclear-pulse rocket powered by nuclear fission. It was carried out by physicist Theodore Taylor and others over a seven-year period, beginning in 1958, with United States Air Force support. The propulsion system advocated for the Orion spacecraft was based on an idea first put forward by Stanislaw Ulam and Cornelius Everett in a classified paper in 1955. Ulam and Everett suggested releasing atomic bombs behind a spacecraft, followed by disks made of solid propellant. The bombs would explode, vaporizing the material of the disks and converting it into hot plasma. As this plasma rushed out in all directions, some of it would catch up with the spacecraft, impinge upon a pusher plate, and so drive the vehicle forward.

Overshadowed by the Moon race, Orion was forgotten by almost everybody except Dyson and Taylor.1 Dyson reflected that "this is the first time in modern history that a major expansion of human technology has been suppressed for political reasons." In 1968 he wrote a paper2 about nuclear pulse drives and even large starships that might be propelled in this way. But ultimately, the radiation hazard associated with the early ground-launch idea led him to become disillusioned with the idea. Even so, he argued that the most extensive flight program envisaged by Taylor and himself would have added no more than 1% to the atmospheric contamination then (c. 1960) being created by the weapons-testing of the major powers.

Being based on fission fuel, the Orion concept is inherently "dirty" and probably no longer socially acceptable even if used only well away from planetary environments. A much better basis for a nuclear-pulse rocket is nuclear fusion – a possibility first explored in detail by the British Interplanetary Society in the Daedalus project.

TAKEN FROM <http://www.daviddarling.info/encyclopedia/O/OrionProj.html>

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