UFO Propulsion Systems By Stanton T. Friedman (Part Three)

By Stanton Friedman

     The design and development of nuclear flight-propulsion systems requires the solution of very real problems associated with complex nuclear physics, and sophisticated hardware operating at very high temperatures, and the lethal radiation produced by the fission process. Similar problems, although not as difficult, were solved first for nuclear weapons and then in the production of large, relatively low-temperature submarine and stationary nuclear-power plants. The primary difficulty in employing fission for space or atmospheric propulsion systems is associated with the weight and high performance limitations of such systems. Large ships weigh more then a hundred thousand tons. Airplanes weigh fewer then four thousand tons, and even the Saturn 5 rocket only weighed three thousand tons.

     Despite the problems the NRX- A-6 nuclear-rocket-reactor propulsion system was successfully tested in December, 1967 by Westinghouse Astro-nuclear Laboratory at a power level of 1.1 billion watts in a package less then ten feet long and under five feet in diameter. In June 1968 the Los Alamos Scientific Laboratory successfully tested the Phoebus-2B at a power level of 4.4 billion watts; it had a diameter less than six feet. The old Grand Coulee Dam produced 2.2 billion watts by comparison. All the NERVA (and preceding KIWI and ROVER) systems used solid fuel, through which was pumped liquid hydrogen, which changed to a gas and was exhausted through a nozzle. Because hydrogen has the lowest weight of any molecule, for the same energy expended it will achieve the highest exhaust velocity. The weight of the oxygen and its associated tankage is also eliminated. More advanced systems have been designed in which the U-235 is in a very high-temperature gas-plasma form and thus provides far higher exhaust temperatures for the hydrogen. Reactors have actually operated with the fuel in gaseous form.

     Of considerably greater interest in a long-term viewpoint would be fusion propulsion. Fusion is the nuclear process involving the combining of light nuclei to make heavier nuclei and, as in fission, convert a small amount of mass into a large amount of energy. It is the primary process by which energy is produced in most stars and in so-called hydrogen bombs. Every civilization—even on distant stars—would become aware of the fusion process as it reached a minimum level of scientific maturity. There are many different reactions and processes, which can be, used in both fission and fusion devices.

     One of the most attractive for a space-propulsion system would be to cause the reaction of just those particles which, when made to fuse, produce only charge rather then neutral particles. These very high-energy particles could then be directed out the back of the rocket, using appropriate electric and magnetic fields. Neutral particles come off in all directions and cannot be directed or controlled, only slowed down and their heat absorbed . . . a very inefficient process.

     Using the right reactions in the right way, a space fusion-propulsion system could be designed to exhaust light ions having more then ten times as much energy per particle as they can receive in a chemical rocket.

     A second advantage of considerable interest is that the fuel or propellant for a fusion rocket would be isotopes of hydrogen and helium, which are not only the lightest elements but are the most abundant in the universe. Thus one could be certain of finding the raw materials for a fusion fuel stockpile in any star system to which one traveled.

     There have been a number of studies published showing that staged fission and fusion deep space propulsion systems are capable of round trips to near-by stars in a shorter time then an average life span. Chemical rockets would be used to launch starships into orbit or to the moon for re-launching from there because of the greatly reduced energy requirements on the moon. Clever design would be employed such as was used by the Lunar landing program. Full advantage would be taken of very “free loading” possibility just as the Apollo vehicle takes advantage of the earth’s rotation to the east near the equator and of the gravitational field of the moon and of staged rockets which fire in programmed succession on the way and on counting on earth’s atmosphere to slow it down rather then carrying and firing retro-rockets to slow it down on the way back.

     The final weight and cost depend almost entirely on the design assumptions rather then (as academic calculations so often assume) being independent of those design features. An early study of the required launch weight of a chemical rocket capable of sending a man to the moon and back concluded that the launch weight would have to be a million, million tons. The launching was accomplished less then thirty years later with a chemical rocket weighing three hundred times less.

     Stars and planets along the way would be used for both their fuel and solar energy and for gravitational assistance, just as the Pioneer spacecraft, which was without propulsion systems after leaving the vicinity of earth, using the gravitational field of Jupiter to hurl itself past Saturn and eventually beyond the solar-system.

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