Nuclear pulse drive
The nuclear pulse propulsion ( English nuclear pulse propulsion or external pulsed plasma propulsion ) is a proposal for the propulsion of spaceships , according to which thrust would be generated by atomic explosions . The principle was developed for the first time in connection with the Orion project of the Defense Advanced Research Projects Agency (DARPA) after Stanisław Marcin Ulam had requested the corresponding in 1947. Newer concepts using inertial fusion have been the basis for most of the post-Orion projects, including the famous Daedalus Project and the lesser-known Longshot Project .
The Orion Project
The Orion project was the first serious attempt to design a nuclear pulse-propelled missile . The work took place at General Atomics in the late 1950s and 1960s . The basic idea was to act with small directional atomic explosions on a steel baffle plate, which is attached to the stern of the spaceship with built-in shock absorbers . High-performance, directional explosive devices produced the highest possible transmission of the impulse ( specific impulses around 6000 s, i.e. twelve times that which occurs with the space shuttle ). Improvements could be up to 100,000 s (1 MN · s / kg). The thrusts were in the range of millions of tons, so that with the materials from 1958 spaceships of more than 8 × 10 6 tons of take-off weight could have been built.
A prototype that could have been constructed of steel like a submarine would have allowed a crew of two hundred men and a takeoff weight of several thousand tons. This comparatively simple vehicle could fly from the Earth's surface to Mars and back in four weeks (compared to the seven months it would take with chemical fuels today). A flight to the moons of Saturn and back would be accomplished within seven months (compared to about nine years with chemical fuels).
While the project was underway, a number of engineering problems were discovered and resolved, primarily related to the shielding of the crew and the life of the baffle plate. When the project ended in 1965 (mainly because of a collision with the Treaty on the Ban on Nuclear Weapons Tests in the Atmosphere, Space and Underwater ), it had emerged that the system was thoroughly feasible. However, because of the fallout, there were ecological and thus ethical concerns about launching such a ship within the earth's magnetic field .
Project Orion technology could be implemented in the near future and used, for example, to deflect an asteroid that is about to collide with Earth . Due to the unusually high performance, such a mission could still be successful even with a relatively late start; the vehicle could act on the asteroid concerned with a high degree of kinetic energy. On a remote-controlled mission, the shock absorbers would also be the most difficult part of the construction.
Orion is one of the very few propulsion technologies that, based on today's technical practice, would already enable a flight to other stars .
The idea in the Soviet Union
In the 1960s, the Soviet Union also toyed with the idea of propelling spaceships with small atomic explosions. Former Soviet minister Viktor Michailow mentions a similar discussion with Andrei Dmitrievich Sakharov :
"I remember that Sakharov once invited us to his office in the early 1960s and told us about his idea of an interstellar spaceship that would be powered by small atomic explosions."
Daedalus project
The Daedalus project was a study carried out by the British Interplanetary Society (BIS) from 1973 to 1978 with the aim of plausibly designing an unmanned interstellar spacecraft that would remove a nearby star from Earth within the lifetime of a single scientist could achieve. Fifty years were set as the upper limit for the duration of the flight. Twelve scientists and engineers worked on the project under the leadership of rocket engineer Alan Bond . At the time, it seemed that rapid advances in nuclear fusion were possible, and inertial fusion in particular seemed to be particularly suitable as a rocket engine, because it causes very small explosions.
It was envisaged that the inertial fusion should take place in an electromagnet , which embodied the rocket engine . The reaction should be sparked by electron beams . After the reaction, the magnet should funnel the hot plasma masses released during this to the stern in order to generate thrust. In order to make the system work safely and efficiently, it should be operated with helium-3 , which should be extracted from Jupiter .
A system of inertial fusion that would be efficient enough for a project in the style of Daedalus can still by far not be implemented today, even if certain designs are already waiting to be confirmed and further substantiated.
Medusa
The Medusa system has more in common with solar sails than with conventional missiles. It was proposed in the 1990s in connection with another British Interplanetary Society project when it became apparent that it would not be feasible to use inertial fusion to power a rocket engine with a spaceship.
A Medusa spaceship would deploy a large sail attached to a cable in the direction of travel and then drop nuclear bombs in the direction of travel, which explode between the ship and the sail. The momentum of the explosion would accelerate the sail, which would pull the ship behind it.
The Medusa system works better than the classic Orion system because the stroke of the shock absorber is significantly larger, the resonance body absorbs a larger part of the impulse of the explosion and all essential components can be designed for tensile stress and therefore very easily overall. In addition, the Medusa system can be scaled down better. Medusa-type ships would create a specific impulse of 50,000 to 100,000 seconds (500 to 1000 kN · s / kg).
Longshot project
Project Longshot's scientific concept work was conducted in collaboration with the United States Naval Academy in the early 1990s and funded by the National Aeronautics and Space Administration (NASA). The basic concept of the Daedalus project was taken up insofar as the drive should take place by the magnetic bundling or funneling of pulses generated by inertial fusion. However, it was assumed that the fusion reaction could not provide both the thrust and the ship (in particular the intended communication laser with a maximum output of 250 kilowatts) with energy, and therefore a conventional nuclear reactor with 300 kW could be used to power the ship should provide. The additional weight of the reactor would reduce the performance, but the ship would be able to reach Alpha Centauri within a hundred years (speed around 13,411 km / s or 48,279,600 km / h) even with the use of lithium hydride as an energy carrier .
With the help of antimatter
According to concepts from the Pennsylvania State University from the mid-1990s, antiprotons in the nucleus of uranium atoms could release an energy that explodes the atomic nucleus as in conventional nuclear fission . Even a small number of such reactions can set the nuclear chain reaction going, which would require considerably more fuel to maintain if it were to be operated differently. While a critical mass of approx. 11.8 kg of plutonium is required in a conventional nuclear power plant or with conventional nuclear weapons , thanks to the use of antimatter you could get by with well under one gram.
Several missile concepts have been proposed based on this relationship. These include those that are intended to enable journeys through interplanetary space with the help of nuclear fission only , and those that are based on the common use of nuclear fission and nuclear fusion for journeys to other stars.
Web links
Individual evidence
- ^ Joseph A. Bonometti, P. Jeff Morton: External Pulsed Plasma Propulsion (EPPP) Analysis Maturation (PDF; 722 kB) Nasa Marshall Space Flight Center. Retrieved December 24, 2008.
- ^ History of Project Orion . In: The Story of Orion . OrionDriv e.com. 2008-2009. Retrieved October 11, 2010.
- ↑ General Dynamics Corp .: Nuclear Pulse Vehicle Study Condensed Summary Report (General Dynamics Corp.) (PDF; 962 kB) US Department of Commerce National Technical Information Service. January 1964. Retrieved December 24, 2008.
- ↑ Gerhard Hegmann: For six billion to Mars to die there . In: Welt Online . January 3, 2014 ( welt.de [accessed June 19, 2016]).
- ↑ Freeman Dyson : Interstellar Transport . 1968
- ↑ From an interview for Nuclear Dynamite , 1998.
- ↑ chief specialist- Soviet atom mongers . Spacebombardment.blogspot.com, July 27, 2005
- ↑ Johndale C. Solem: Nuclear explosive propulsion for interplanetary travel: Extension of the MEDUSA concept for higher specific impulse . In: Journal of the British Interplanetary Society , Vol. 47, No. 6, pp. 229-238. bibcode : 1994JBIS ... 47..229S . On the Medusa concept, see the January 1993, June 1994 and November / December 2000 issues of the Journal of the British Interplanetary Society .