Defense Intelligence Reference Document Advanced Nuclear Propulsion For Manned Deep Space Missions

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The Super Marx generator therefore can accomplish on Earth what the spacecraft acting
as a large capacitor can do in space.
The testing of an Argon ion laser driven by high explosives can, of course, be done on
Earth, and the same applies to the conjectured superexplosives.
Conclusion
If large-scale manned spaceflight has any future, a high-specific-impulse, high-thrust
propulsion system is needed. The only known propulsion concept with this property is
nuclear bomb propulsion. However, since large-yield nuclear explosions are for obvious
reasons undesirable, the nuclear explosions should be comparatively small. But because
of what Freeman Dyson described as the "tyranny of the critical mass," small fission
bombs or fission-triggered fusion bombs become extravagant, with only a fraction of
the nuclear material consumed. 1
In the original Orion bomb propulsion concept, the propulsive power was through the
ablation of a pusher plate. There the energy is delivered to the pusher plate by the
black-body radiation of the exploding bomb. The propulsion by non-fission-triggered
fusion bombs not only has the advantage that it is not subject to the "tyranny of the
critical mass," but the propulsive power is there delivered by the kinetic energy of the
expanding hot plasma fireball repelled from the spacecraft by a magnetic mirror. This is
particularly true for a pure deuterium bomb, where, compared with DT, more energy is
released into charged fusion products (in a DT bomb, 80 percent of the energy goes
into neutrons).
Whereas in a fission explosion most of the energy is lost into space by the undirected
black-body radiation, much more propulsive energy can be drawn from the plasma of a
pure deuterium fusion bomb explosion, in conjunction with a magnetic mirror.
Manned space flight requires li~ing large masses into Earth orbit, where they are
assembled into a large spacecraft. While this can be done with chemical rockets, it
would be much more economical if it could be done with a chain of small nuclear
explosions. Without radioactive fallout, this can be done with a chain of laser-ignited
fusion bombs, with one laser for each bomb, where the lasers become part of the
exhaust. Ignition can be done not by infrared chemical or CO2 lasers, as was suggested
by the Los Alamos team (Reference 18), but rather by an ultraviolet laser driven by
high explosives, as suggested by the author (Reference 9).
Looking to the future, using deuterium-widely available on most planets of the solar
system and in the Oort cloud outside the solar system-as the nuclear rocket fuel would
make manned space flight to the Oort cloud possible, at a distance at about one-tenth
of one light year.
1 The same is true for nuclear fission gas core rocket reactors, where much of the unburned fission fuel is lost in
the exhaust.
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