The design envisaged propelling a spaceship with a nuclear pulse drive through a series of atomic bomb explosions , each of which takes place at a distance of only a few meters behind the stern of the spaceship. Protected by a massive protective shield and a shock absorber system, the spaceship “rides” on the shock waves of the explosions. A nuclear pulse engine based on the Orion principle combines a high specific impulse with a high thrust . This is a unique property among propulsion methods for space travel .
The Orion Project was started in 1957 by General Atomics under the direction of Theodore B. Taylor and Freeman Dyson . It was sponsored in turn by the US military research agency ARPA , the United States Air Force, and NASA . The funding always remained within a framework that kept the project at the stage of a feasibility study . There was never a test run of the drive or the construction of a prototype, only model tests with conventional explosives were carried out. The project was canceled in 1965 for political reasons and because of the 1963 Treaty banning nuclear weapons tests in the atmosphere, in space and underwater .
The story of the Orion project is determined by the attempt to achieve a permanent supply of financial means. The project was passed on to a number of donors one after the other, which are also characteristic of the respective design phases. Although the donors each provided enough funds to continue the project, it was not possible to obtain sufficient funding for a prototype. As a result, the project never got beyond the status of a feasibility study.
The principle of a spacecraft powered by gunpowder explosions goes back to independent work by Hermann Ganswindt (proposed from around 1880, published in 1891) and Nikolai Iwanowitsch Kibaltschitsch (proposed 1881, published 1918). Ganswindt describes z. B. a "world vehicle", which should be propelled with a series of dynamite explosions. The first scientific study on a vehicle powered by dynamite explosions was published in 1900 by Roman Gostkowski .
The first proposal to propel a spaceship with atomic bombs was made in 1946 by Stanisław Marcin Ulam in a publication published in 1956 with Cornelius Everett on the mathematical basis for a nuclear pulse drive. The Atomic Energy Commission was later awarded a patent based on this design.
Start of the project
In 1956, General Atomics was founded under the leadership of Frederic de Hoffmann as a subsidiary of General Dynamics ; It had set itself the corporate goal of harnessing the then unimagined possibilities of the newly discovered nuclear energy. Francis de Hoffman succeeded in recruiting many of the physicists who worked in Los Alamos during the Second World War to work at General Atomics. It offered them a working atmosphere in which the scientists, as in Los Alamos, could work creatively on their own ideas without being hampered by bureaucracy. One of these physicists was Ted Taylor , who in turn was able to convince Freeman Dyson to work for General Atomics for a year.
Together they first developed the TRIGA reactor , but then turned to the shared dream of peaceful exploration of the solar system. Taylor had come across Ulam's ideas in Los Alamos, and so he and Dyson began to work on the first drafts of a spaceship with a nuclear pulse drive. Under the ambitious motto "To Mars by 1965, to Saturn by 1970", Taylor and Dyson planned missions to explore the solar system.
The first drafts envisaged a 60 meter high spaceship shaped like a projectile with a baffle plate 40 m in diameter. The spacecraft with a mass of 4,000 t was to carry a payload of 1,600 t into orbit and launch from the ground in Jackass Flats , part of the Nevada Test Site . It was supposed to carry 2600 propellant charges, of which around 800 propellant charges with an explosive force between 0.15 kt and 5 kt would have been necessary to reach orbit, the remaining propellant charges would have made a round trip to Mars and even Saturn possible.
Triggered by the Sputnik shock , the Advanced Research Projects Agency ( ARPA , an agency of the United States Department of Defense that carries out research projects) was founded in February 1958 . This should promote space projects in a bundle. In April of the same year Taylor and Dyson presented their spaceship design to ARPA, which then funded the project with $ 1 million.
The Orion project at ARPA
After NASA was founded in July 1958, ARPA's space projects were split between it and the Air Force. NASA took over all civil space projects, the Air Force the military. However, neither NASA nor the Air Force showed any interest in the Orion project. The Air Force did not see Orion as a future weapon; NASA had made the decision that its civil space program should be non-nuclear and not classified. The Orion project was the only space project to remain with the ARPA.
It turned out to be a hindrance to the financing that many budget officers thought the project was "crazy". They couldn't believe that it was possible to propel a vehicle with an explosion without damaging or destroying it.
"We use bombs to blow things into pieces, not to make them fly."
"We use bombs to blow things up, not to let them fly."
In order to show the basic technical feasibility of an explosion-powered vehicle, a model with a baffle plate one meter in diameter, the so-called hot rod or putt-putt, was built . The fiberglass model, weighing 120 kg, successively ejected up to six propellant charges of approx. One kilogram from C4 . With this model, a flight was achieved on November 14, 1959 with a peak height of 56 m, two days later an altitude of about 100 m was reached. A film about the successful flight attempts subsequently helped to secure further funding. One of the models is now in the Smithsonian Institution's National Air and Space Museum .
The flight tests with the models provided knowledge that was directly useful for further development, for example what shape the impact plate had to have in order to achieve a favorable ratio of weight and stability. In addition, the flight tests showed that, at least due to the temperatures and pressures that could be achieved with conventional explosives, no material erosion ( ablation ) was to be expected on the surface of the impact plate. The ablation was further investigated in further experiments with plasma generators designed to simulate the bomb plasma.
The Orion project in the Air Force
The ARPA decided in late 1959 not to support the Orion project for reasons of national security. The US Air Force then took over the project, but only on the condition that military applications were found. But that stood against the actually intended peaceful use of the project.
“Offically it has to be justified to the budgetiers as a military program. So they had to invent fake military requirements for it. "
“Officially, it had to be justified to the budget providers as a military program. So they had to invent tricked military requirements. "
From a military point of view, small Orions should now be used like a modern ICBM with multiple independently targetable reentry vehicles (MIRVs). They should take off from silos, fly over the target area and first drop a large amount of decoys there . Only when the enemy defenses were overloaded by the decoys should the actual warheads be launched. Another proposal was for large Orion spaceships that would patrol deep space with a mission profile similar to that of modern strategic submarines .
Some military officers took the military possibilities seriously. The Cold War was in full swing, the nuclear arms race had begun. Thomas Power , the head of Strategic Air Command , even believed that "whoever controls Orion controls the world". At his instigation, a model of a military Orion spaceship was built in March 1962, fully armed. This "battleship" was supposed to be armed with 500 warheads. The model was shown to President John F. Kennedy when he visited Vandenberg Air Force Base . Kennedy was shocked and denied the project the political support it needed. In the middle of the Cold War, Kennedy didn't want to risk a nuclear arms race in space.
The Orion project at NASA
Defense Secretary Robert McNamara prevented further development of the Orion project in the Air Force . He did not see Orion as a military project and therefore refused extended funding, without which the construction of a prototype was not possible. In order to bring the project beyond the status of a feasibility study, Taylor and Dyson turned to NASA, from which they were hoping for additional funding.
The drafts were adapted to the requirements at NASA. One wanted to refrain from a ground start, since it would have been too "dirty" to take place without massive public protests. Instead, the size of the Orion ships was adapted to the available launch vehicles - the Orion design, which was adapted to the Saturn missiles, now had a baffle plate ten meters in diameter. One variant ( lofting ) provided for using a Saturn 1C stage as a booster . This should bring the Orion spaceship to a height at which the safe ignition of the nuclear pulse drive was possible. A second variant ( boost-to-orbit ) provided for three individual parts, each of which was brought into orbit by a Saturn V rocket and was to be assembled there.
A Mars mission with a crew of eight and a payload of 100 tons was envisaged as a possible target. A travel time of 125 days was planned for the round-trip flight for this mission, which was less than half the travel time of a conventional mission.
NASA leaders were not convinced of Orion and were reluctant to fund the project. Only Wernher von Braun recognized the possibilities of the Orion project after initial skepticism and wrote an article that vehemently supported the project, but without obtaining further financial support.
End of the project
Many factors contributed to the end of the Orion project. The project was so secret that few potentially interested people from science and technology knew about it and therefore no broad-based support could be given. Orion also faced stiff competition from the NERVA project when it came to using nuclear energy for space flight . The public enthusiasm for nuclear power that had prevailed in the 1950s, such as the Ford Nucleon , had evaporated. After the Cuban Missile Crisis and the first reports of strontium -90 in breast milk, nuclear power created fear in the population. NASA would have loved to have nothing to do with a project that used atomic bombs as a drive, and feared a publicity disaster if it actually took off.
One of the decisive factors in the suspension of the Orion project was the 1963 Treaty banning nuclear weapons tests in the atmosphere, space and underwater (NTBT). This prevented the further development of the nuclear propellant charges and the operation in space in general. Since the Orion project basically represents a peaceful use of nuclear power, it would have been possible to obtain an exemption. Ted Taylor even had the hope of being able to bypass the NTBT on a joint mission with the Soviet Union . However, there was a lack of political support for this.
In the end, it was the budget dispute between the Air Force and NASA that caused the project to fail. The Air Force only wanted to partner with NASA if NASA provided the project with significant funding. However, after strong pressure from the Apollo program, NASA was finally forced in December 1964 to cancel the funds for the Orion project. As a result, the Air Force also stopped funding - the Orion project was effectively ended. On June 30, 1965, the official instruction was given to discontinue the project.
Freeman Dyson wrote an essay in 1965 setting out the reasons for the failure of the Orion project. Dyson complained that the Orion project failed not because of a lack of technical possibilities, but because of a lack of political support:
"... because this is the first time in modern history that a major expansion of human technology has been suppressed for political reasons."
"... this is the first time in modern history that a substantial expansion of human technology has been suppressed for political reasons."
Much of the work produced during the Orion project is still classified, including the second part of the Nuclear Pulse Space Vehicle Study , Vehicle System Performance and Costs, or Wernher von Braun's essay, with which he supported the Orion project. Above all, the work on the structure of the propellant charges remains secret, as it describes how to build small atom bombs that could also be of interest to terrorists.
Principle of the Orion drive
A nuclear pulse drive works by ejecting special atomic bombs from the stern of the spaceship at regular intervals (about every second) , which detonate shortly afterwards in a directed explosion at a distance of a few meters (depending on the design about 35 m). The resulting plasma hits a massive impact plate ( pusher ) at the stern of the spaceship and generates a mechanical impulse there that accelerates the impact plate. Shock absorbers are located between the baffle plate and the payload , which are intended to convert the pulsed acceleration of the baffle plate into the most uniform possible acceleration of the spaceship.
|Orion (1958)||Orion (1965)||Saturn v|
|total weight||4000 t||100-750 t||3000 t|
|Specific impulse||4000 s||1800-2500 s||418 s ( J-2 )|
|diameter||40 m||10 m||10 m|
|height||60 m||50 m||111 m|
|Payload (300 mi orbit , ≈480 km)||1600 t||-||133 t|
|Payload (moon landing)||1300 t||200 t (from earth orbit)||52 t|
The Orion drive combines a high specific impulse with a high thrust , which is unique for a spaceship drive . The specific impulse (impulse per unit mass or unit weight of fuel) for a simple Orion spaceship has been reduced to up to 20,000 seconds. calculated - far higher than with currently used chemical fuels (approx. 450 sec.). The atomic bombs and thus also the baffle plate that absorbs the momentum cannot be built arbitrarily small. Since the payload must be protected against the radiation generated by the explosion , designs for Orion spaceships usually have comparatively large masses of at least 300 tons. As the size of the baffle plate increases and the spacecraft mass increases, so does the efficiency of the drive.
The baffle plate is the component that would be exposed to the greatest loads in an Orion spaceship. These are, on the one hand, ablation (i.e. the removal of material from the surface of the impact plate by the bomb plasma), and, on the other hand, the mechanical stress caused by the violent impact that act on the impact plate with every bomb explosion.
During the experiments with conventional explosives it was already found that the baffle plate had to be conical with a thinner edge and thicker towards the middle so that it would not burst in the event of an explosion.
In an experiment by the physicist Lew Allen during Operation Redwing , two approximately 30 cm large, graphite-coated steel balls were suspended from wires only ten meters from the 20-kt bomb. These balls were thrown away by the explosion. After they were collected again, however, it was found that the balls were intact and the surface was only worn away by a few thousandths of an inch . This showed that the problem of ablation was solvable.
Now materials had to be found with which the impact plates could survive a round trip with 2,600 loads. For this purpose, experiments were made with plasma generators, which worked in a similar way to a shaped charge . When someone left a fingerprint on the test object during one of these experiments, it was found after the experiment that the fingerprint had prevented the ablation at this point. So the idea came up to spray the baffle plate with oil, which serves as a regenerable ablation layer and thus considerably increases the life of the baffle plate.
The shock absorbers reduce the strong acceleration peaks caused by the propellant charge explosions to values that are tolerable for the payload and the crew. The shock absorption system has two levels and can be compared to the shock absorption system of a car. The first stage corresponds to the tire, the second stage to the shock absorber, which connects the tire to the chassis.
The first stage should consist of concentrically arranged, gas-filled rings that connected the baffle plate to an intermediate plate. This first stage was intended to dampen the short acceleration peaks acting on the baffle plate to values that could be mechanically managed by the subsequent second stage. This second stage consisted of a bundle of columnar shock absorbers attached to the payload section. They reduced the acceleration acting on the payload to a few g .
In the 4000 t design, the shock absorbers were designed with a spring deflection of ten meters. With a pulse frequency of 1.1 s, an average acceleration of 1.25 g should result, the actual acceleration depending on the load on the spaceship; unloaded the acceleration would have been higher. The shock absorbers should be actively cooled, the evaporating coolant would have been reused to expel the propellant charges. In the NASA designs, the shock absorber system was basically viewed as lossless.
The nuclear propellant charge ( Charge Propellant System or Pulse Unit ) is intended to convert the energy released during a nuclear explosion into a plasma cloud of propellant that is directed at the impact plate and moves at high speed.
Ulam's original design stipulated that discs of propellant would be ejected along with the nuclear propellant charges. These discs made of light material such as water or polyethylene were supposed to be vaporized by the nuclear explosion and hurled towards the baffle plate. The later designs incorporated the propellant into the propellant charges. The propellant was now tungsten , which was located as a flat disk at the tip of the propellant charge. The propellant should not only serve to transmit the impulse, but at the same time shield part of the radiation generated during the explosion.
The nuclear propellant charges were designed to hurl this propellant in a directional explosion in the direction of the impact plate. The aim was to bring the cone, in which the propellant is thrown away, into congruence with the impact plate in order to capture as much of the energy of the bomb explosion as possible.
At the same time, the propellant charges should be as small, efficient and “clean” as possible, that is, generate as little fallout as possible . Ted Taylor was busy designing the propellant charges, from whose hand the smallest nuclear warhead came with the Davy Crockett . The Davy Crockett can be adjusted in terms of its explosive power - a feature that was also interesting for the Orion propellant charges, since half charges were required to start or stop the Orion propulsion system. For the flight through the atmosphere, even finer divisions of the explosive force of 0.15 kt and 5 kt were required for constant acceleration, as the air would absorb additional energy and pass it on to the impact plate. For normal space flight only a constant strength was necessary.
For the design of the systems for handling the propellant charges inside the spaceship, consultants from the Coca-Cola Company were called upon , as their machines for filling bottles were viewed as a good template.
Another challenge was the positioning of the propellant charges behind the impact plate. Initially, systems were envisaged that would shoot the propellant charges sideways past the impact plate. They were later to be shot with a gas pressure cannon through a hole in the center of the baffle plate.
Because Orion was supposed to be powered by nuclear explosions, it would inevitably have been exposed to radiation . This could have had a direct impact on the crew, indirectly through fallout or through accidents.
In order to minimize the radiation exposure of the Orion crew during the powered flight, the crew should be in a radiation- protected flight station during this time . This flight position could also have been used as a retreat zone in the event of solar storms . The aim was to limit the radiation dose absorbed per mission to 500 mSv . Outside the flight level, however, staying with the engine running would have been fatal. The residual radiation remaining after switching off the drive would have died down quickly and the drive section would have been accessible for maintenance and repair work after a few hours.
A ground launch would have exposed the atmosphere to radiation from fallout. For the flight beyond the atmosphere, about 100 kt would have been required for the 4,000 t design; In comparison, atmospheric atomic bomb tests totaling 100 Mt were carried out annually during the conception period. Dyson did theoretical calculations and came to the conclusion that statistically ten people would die from the fallout for every ground start - a number Dyson found unacceptable. It was hoped that the development of propellant charges would lead to the “cleanest” possible nuclear fission, which would release less radioactivity. When operating outside of the atmosphere, charged radioactive particles trapped by the Earth's magnetic field contribute to the fallout. There are also electromagnetic pulses .
There was also a risk of radioactivity being released through accidents. The three scenarios considered were misfires while the engine was still running, an aborted take-off and missing orbit with a subsequent fall back to Earth. In all three scenarios, there would not have been any unwanted nuclear explosions, but it is very likely that the conventional explosives contained in the propellant charges would have exploded, releasing radioactive material. The aim was to keep the impact on inhabited areas as low as possible by using suitable launch sites, for example in the middle of the sea.
Should it become necessary, an Orion spaceship could well be built with today's technical means. George Dyson even calls Orion a “standard technology”.
NASA has founded a small project group that is again dealing with a nuclear pulse drive under the name External Pulsed Plasma Propulsion (EPPP). However, since NASA had difficulties in obtaining the basic work on the Orion project itself, it bought almost 2000 pages of project documentation from George Dyson, who had collected it for his book on the Orion project. This project group sees two possible uses for EPPP spaceships. On the one hand, there are interplanetary journeys that could be carried out faster, more flexibly and with more payload with this drive, and on the other hand, it is the defense against comets or asteroids on a collision course with the earth. With EPPP, a range would be available that is sufficient to have enough time to change the path of the object. In addition, the drive itself could be used to change the path of the object, ie to "drive" it.
The Orion drive is always a motif in science fiction . As a rule, however, it does not go beyond a mere mention - one example is the film Deep Impact , in which the propulsion of the spaceship is referred to as the Orion propulsion, but the typical structure of an Orion propulsion gives way to the film cliché of a spaceship with rocket nozzles had to.
The spaceship Discovery in Stanley Kubrick's film 2001: A Space Odyssey was initially planned as an Orion-powered spaceship. But after Kubrick got Dr. Strange or: How I learned to love the bomb had finished shooting, he didn't want to make another film with atomic bombs and so changed the script. Orion remained the only name for the shuttle that Dr. Heywood brings Floyd to the space station.
An example of a more realistic implementation of the plans of the Orion project, however, are Larry Nivens and Jerry Pournelle's science fiction novel Fußfall ( Footfall ), Stephen Baxter's The Last Arche ( Ark ) and Dan Simmons ' Ilium ( Ilium ), in which the Use of a spaceship with Orion propulsion is depicted. Gerhard Seyfried's 1999 comic book Starship Eden also shows a huge spaceship with a nuclear pulse drive, which can cause some problems when using it.
General Atomics : Nuclear Pulse Space Vehicle Study .
- Volume I - Summary . September 19, 1964 (PDF, 3.19 MB)
- Volume III - Conceptual Vehicle Designs And Operational Systems . September 19, 1964 (PDF, 7.76 MB, English)
- Volume IV - Mission Velocity Requirements And System Comparisons . February 28, 1966 (PDF, 18.9 MB)
- Volume IV - Mission Velocity Requirements And System Comparisons (Supplement) . February 28, 1966 (PDF, 25 MB, English)
- NASA: Nuclear Pulse Vehicle Study Condensed Summary Report (General Dynamics Corp) . January 1964 (PDF, 939 kB, English)
- AIAA : Nuclear Pulse Propulsion: Orion and Beyond . 19 July 2000 (PDF, 2.86 MB, English)
- George Dyson : Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 . (English)
- John McPhee : The Curve of Binding Energy: A Journey Into the Awesome and Alarming World of Theodore B. Taylor . Farrar, Straus and Giroux, New York 1974. (English)
- Kenneth Brower: The Starship and the Canoe . Harper, New York 1983.
- History Channel : History Undercover - Code Name: Project Orion . October 31, 1999
- BBC Four : To Mars by A-Bomb: The Secret History of Project Orion . March 26, 2003
- Spiegel Online : Project Orion - The ride on the bomb (also published in GEO WISSEN No. 33).
- The Internet Encyclopedia of Science: Project Orion (English)
- Michael Flora: Project Orion: Its Life, Death, and Possible Rebirth (English)
- Rhys Taylor: Project Orion a re-imagining . Video with an artist rendering of an Orion spaceship.
- Georg Dyson on the "Orion" project TED talks, 2002, accessed on April 5, 2013
- Hermann Ganswindt: The Last Judgment; Inventions by Hermann Ganswindt . Berlin 1899.
- Roman Baron Gostkowski: A modern Icarus. In: The time . No. 304, Vol. XXIV, July 28, 1900, pp. 53-55. limited preview in Google Book Search - USA
- Stanisław Marcin Ulam: On a Method of Propulsion of Projectiles by Means of External Nuclear Explosions . Los Alamos Technical Reports (LAMS), August 1955.
- Patent GB877392 : Nuclear propelled vehicle, such as a rocket. Published September 13, 1961 , Applicant: Atomic Energy Commission.
- "Mars by 1965, Saturn by 1970" . AIAA : Nuclear Pulse Propulsion: Orion and Beyond (PDF; 3 MB). 19 July 2000, p. 4.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 149.
- DrCarstairs: Hot Rod. July 14, 2009, accessed February 16, 2019 .
- object A19721008000: Propulsion Test Vehicle, Project Orion
- AIAA: Nuclear Pulse Propulsion: Orion and Beyond (PDF; 3 MB). 19 July 2000, p. 5.
- BBC Four: To Mars by A-Bomb . 44 min 30 sec.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 138.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , pp. 205 ff.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 6. "Whoever controls orion will control the world"
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , pp. 220 ff.
- BBC Four: To Mars by A-Bomb . 46 min 55 sec.
- AIAA: Nuclear Pulse Propulsion: Orion and Beyond (PDF; 3 MB). 19 July 2000, p. 6.
- Wernher von Braun: Nuclear Pulse Propulsion System - Its Potential Value to NASA . 1964.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 255.
- NASA : Nuclear Pulse Vehicle Study Condensed Summary Report (General Dynamics Corp) (PDF; 962 kB). January 1964, p. 10.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 266 ff.
- AIAA : Nuclear Pulse Propulsion: Orion and Beyond (PDF; 3 MB). 19 July 2000, pp. 7-8.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 268.
- Freeman Dyson: Death of a Project. In: Science , Volume 149, Issue 3680, July 1965, pp. 141-144.
- AIAA: Nuclear Pulse Propulsion: Orion and Beyond (PDF; 3 MB). 19 July 2000, p. 7.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 296.
- George Dyson : Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 55.
- AIAA : Nuclear Pulse Propulsion: Orion and Beyond (PDF; 3 MB). 19 July 2000, p. 6.
- Here the experiment "Inca" is mentioned in various sources. George Dyson and John McPhee do not provide any specific information. During the test series Operation Teapot , Operation Redwing and Operation Plumbbob , however, experiments were carried out with graphite-coated steel balls. These were Teapot Project 5.4, Redwing Project 5.9 and Plumbbob Project 8.3b. (See list of projects in the PLUMBBOB test series ( Memento of the original from March 22, 2005 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. and Shot Smokey. A Test of the PLUMBBOB Series. August 31, 1957, p. 64.)
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 127 ff.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 179.
- General Atomics : Volume III - Conceptual Vehicle Designs And Operational Systems (PDF; 8.1 MB). September 19, 1964, p. 6.
- The Air Force called the propellant charges Charge Propellant Systems , NASA called them Pulse Units , Ted Taylor called them simply bombs. Compare John McPhee : The Curve of Binding Energy: A Journey Into the Awesome and Alarming World of Theodore B. Taylor . Farrar, Straus and Giroux, New York 1974, p. 175.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 24.
- General Atomics: Volume III - Conceptual Vehicle Designs And Operational Systems (PDF; 8.1 MB). September 19, 1964, p. 9 ff.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 177.
- General Atomics: Volume III - Conceptual Vehicle Designs And Operational Systems (PDF; 8.1 MB). September 19, 1964, pp. 97, 100.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 230.
- General Atomics: Volume III - Conceptual Vehicle Designs And Operational Systems . September 19, 1964, p. 94 ff. (PDF; 8.1 MB)
- Carl Sagan : Our Kosmos - A journey through the universe . Droemersche Verlagsanstalt Th. Knaur Nachf., Munich 1991 (new edition), ISBN 3-426-04053-0 , p. 215: "[...] although we could build Orion today if we wanted."
- "[...] the only off-the-shelf technology [...]". ted.com: George Dyson on Project Orion . 7 min 45 sec.
- Freeman Dyson: "Interstellar Transport." In: Physics Today , Volume 21, Issue 10, October 1968, pp. 41-45.
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , p. 292.
- NASA: External Pulsed Plasma Propulsion and Its Potential for the Near Future (PDF; 607 kB). 1999.
- Internet Movie Database : Goofs for Deep Impact .
- George Dyson: Project Orion: The True Story of the Atomic Spaceship . Owl Books, New York 2003, ISBN 0-8050-7284-5 , pp. 270ff.