The pulsated nuclear propulsion is a method of space Propulsion which uses nuclear explosions to produce a push. It was inspired by Stanislaw Ulam in 1947 and was the subject of studies advanced within the framework of the Projet Orion in the years 1950-1960. Since, various techniques and nuclear formats of explosions are regularly proposed, of which the famous Projet Daedalus.

Orion project

See also: Project Orion

The Orion project is the first serious attempt at design of a vehicle with nuclear impulses by General Atomics under the aegis of the ARPA of 1950 to 1963. The rocket released small directional nuclear loads behind it and recovered the push of the blast of the explosion on a large metal plate assembled on a damper system.

The first variations of this principle promised vessels of enormous size capable of takeoff from terrestrial surface and of fast space flights with a single stage, the thermonuclear versions were to allow space flights. These potentialities were accessible with the techiques ones and materials from the beginning of the year 1960.

The last reports/ratios, directed towards a more immediate realization and missions, proposed two modules of basic propulsion and varieties of vehicles manned or not. The smallest module, with its 10  m of diameter was mountable on a Fusée Saturn. Finally, the project was cancelled after the Traité prohibition partial of the nuclear tests of 1963 which returned its settling impossible and its use.

Soviet version

With the beginning of the year 1960, Sakharov, I remember, had invited us in his office to expose us this idea of interstellar spaceship which would have been propelled by nuclear microphone-explosions |Viktor Mikhailov, Soviet former minister and Russian minister delegated to atomic energy (MinAtom) |

Daedalus project

See also: Project Daedalus

The Daedalus Project was a study led of 1973 to 1978 by the British Interplanetary Society for the design of an automatic interstellar probe able to reach a star close in space the 50 years. A dozen scientists and engineers directed by Alan Bond took part in it. At the time, research on the nuclear Fusion was in full rise and promising, in particular on the Fusion by inertial confinement (ICF), and made it possible to consider it like means of medium-term propulsion.

Daedalus was to be propelled by the fusion of pastilles of mixture Deutérium/Helium-3 bombarded by electron beams in a magnetic conduit. The vehicle made up of two stages would have reached 12  % of the Speed of light after approximately 4 years of operation. Incompetent to slow down and to inject themselves into the system of destination, his mission would have consisted only of one overflight of this system.

In 2006, from its dimensions and technologies which it brings into play, Daedalus is always located far from the field of feasibility.

Medusa

The concept of Medusa holds more veil than of the conventional rocket. He was proposed in the years 1990 by Johndale C. Solem and was published in the newspaper of British Interplanetary Society when it proved that fusion ICF could not at the same time propel and feed the Daedalus vessel as it was envisaged.
A Medusa vessel has a large sail deployed in front of him and gréée with the vessel by cables. It releases nuclear loads, the fact of exploding between the vessel and the sail which is then pushed by the wave of plasma and tractor draws the vessel. The concept is more effective than the Orion system because it intercepts proportionally more plasma (veil in larger Spinnaker covering solid Angle), requires less shielding (distance of larger detonation) and of machinery for the absorption of the shocks (servo Winch). It could reach a specific impulse of: 50000 with: 100000  S.

Longshot project

See also: Project Longshot

The Longshot project was a research program of NASA carried out in collaboration with the naval Académie of Annapolis to the beginning of the year 1990. The principle differs little from that of Daedalus: the fuel is amalgamated in a magnetic room then channeled in a magnetic tunnel (what makes it possible to recover by induction electrical energy necessary to the following shooting). As fusion ICF does not make it possible to feed the vessel, it is equipped with a conventional Nuclear reactor of 300  kw.

The objective is to reach in 100 years the system triples Alpha Centauri, nearer close to the Sun (distant to 4,36  Al), and to inject itself in orbit around Alpha Centauri B. The engine would function during the totality of the transit accelerating (then decelerating) permanently the vehicle.

VISTA

VISTA, for Vehicle for Interplanetary Space Transport Applications, is a version with more small scales of Daedalus studied by the National laboratory of Lawrence Livermore medium of the years 1990 and intended for the inhabited interplanetary missions. The fusion of fuel D-T is obtained by inertial confinement by laser beams direct or returned by mirrors. The power and the push of the engine are adjusted by the frequency of injection of the pastilles and the propelling hydrogen dispersion around them.

The general configuration of the vessel is in the shape of cone, the cargo being placed on the circumference of the base, thus protected from radiations by the whole of the structures and equipment laid out on surface of this cone. The vehicle is in rotation, getting an artificial gravity on the level of the cockpits.

Such a vessel of 6000  T, of 100  m height and as much of ray would reach a specific impulse of 16  000  S and would allow return tickets about Mars in 60 days with 100  T of freight.

Catalyze antimatter

To the same time, the research led to the Pennsylvania State University brought to consider the use of small quantities of antimatter to largely catalyze fission in chain of a subcritical mass fissile material. It resulted the design from it from the family of vessels ICAN-II for the exploration of Mars or from external planets.

The system of propulsion ejects in its magnetic conduit of the fuel balls made up of a lead sheath (propelling mass and protection for storage) surrounding a core of uranium containing of the bubbles of mixture D-T. At the burning point, laser beams strike the ball and an amount of antiprotons is drawn top. Annihilation causes an avalanche of neutrons amorçant fission in chain of uranium, the fission energy lights the fusion and the ejection of the resulting plasma (primarily composed of the lead of the sheath) produced a push on the magnetic conduit.

MTF HOPE

In 2002, group HOPE ( Human Outer Planet Exploration ) of NASA was charged to study the possibilities of voyages inhabited towards external planets. He then proposed several solutions of propulsion including one based on magnetized target fusion ( magnetized target fusion , MTF). In a magnetic conduit, small a swell of plasma of mixture D-T is bombarded by guns drawing from the jets of plasma of deuterium followed by hydrogen. The inertial confinement causes the fusion D-T which itself lights fusion D-D in the encircling zone, hydrogen in tail of jet heated by fusion is used as propelling fluid

The selected missions of reference were a stay of 30 or 180 days on Callisto. The typical design of vehicle HOPE is a long mast with the engine at an end and the cockpit with the other, protected by the tanks and equipment. With more 120  m length, it can get by rotation an artificial gravity with the crew. Version MTF HOPE develops 5800  kN of thorough and a specific impulse exceeding 70  000  S, which enables him to carry out each mission in ≈650  J with an initial mass of 650 or 750  T.

See too

• nuclear Propulsion (astronautics)
• space Propulsion

References

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