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Orion Drive

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AKA "Ol' Boom-Boom".

"So the ship gets flung into the atmosphere by the nuclear explosion that just happened under it. Then what? It's going to start slowing down eventually, right? Well, you drop another nuke out of the concave (and heavily armored) bottom of the ship, and detonate it when it gets about 200 feet away. Rinse and repeat until you're in orbit. What could possibly go wrong?"

When you get into space, you're going to need some kind of drive to make moving around easier. If you can't get Artificial Gravity to work your Reactionless Drive, perhaps you need to look at something simpler. Preferably with lots of explosions. You might consider implementing an Orion Drive, an old project that was thought up during the Cold War. Explosive Propulsion meets nuclear weapons, you've got the potential to move much larger ships than normal. The researchers working on this project tended to include things like barber's chairs in their ship designs just to emphasize how much mass they could move.

A basic Orion Drive is composed of a Cool Ship, a large armor plate, and enough high yield weapons to set it in motion. They don't necessarily have to be nuclear, but they need to have the equivalent explosive power. A common variant is to have the explosive material be smaller pellets of frozen deuterium-tritium mix, which would then be induced into nuclear fusion by a laser; this is essentially an H-bomb without having to use an A-bomb to set it off. Note that such inertial confinement fusion propulsion systems are not properly termed Orion drives.

While this may all sound like madness, scale-model tests with conventional explosives have established that the design is perfectly workable. The main obstacle to actually building one of these is the logistics of lifting the components into orbit, since for reasons that probably need little elaboration, nuclear detonations inside the planet's atmosphere are deprecated these days.

A common form of harder sci-fi propulsion systems. See also Explosion Propulsion.


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    Anime & Manga 
  • Gundam: Thermonuclear propulsion is commonplace in the "Universal Century" continuity, used primarily for extremely massive vessels like space colonies, most notably the asteroid base Axis which used it to move freely throughout the solar system. Officially it actually uses solid fuel pellets which are forced to undergo nuclear fusion with lasers or particle beams, but in the movie Char's Counterattack, a nuclear warhead is actually detonated in the thruster cones of Axis in order to propel it on a collision course for Earth.

    Comic Books 
  • Atomic Robo has an Orion Drive-based ship appear in Volume 6. Developed in secret, its planned launch is the driving force of the plot by ALAN to leave Earth for a voyage of discovery and kill Robo, as its launch would cause enough radioactive fallout to wipe out all life on Earth, leaving Robo as the last survivor, who would then almost certainly chase after it.
  • Halo: Tales From Slipspace: When the crew of the UNSC Nereid is stranded deep in space, Commander Coffey makes the suggestion to use the ship's nukes as a means of propulsion, based on early interstellar engines. However, Major Tanris runs the math and discovers that the yield of their modern 26th century nukes far exceeds that of 22nd century Orion engines, meaning the explosion would actually destroy their entire ship. Coffey's real plan was to Mercy Kill everyone aboard rather than spend more weeks starving and fighting over dwindling resources.
  • The Inhumans: When the Inhumans migrate into space, at one point they use a propulsion system that's basically powered by a strapped down Black Bolt shouting through an aperture into space opposite the direction they wanna travel. The physics of it are esoteric, because Black Bolt's power is ostensibly an absurdly powerful sonic scream, so it shouldn't work in space, but it has convoluted properties that make it technically not solely sonic, so it generates propulsive force they can use.
  • Tintin: The rocket designed by Professor Calculus in "Destination Moon" and "Explorers on the Moon" is propelled by slow-detonating nuclear fission explosions. The engine is made of "calculon", a silicon-based material that was invented by Calculus to withstand the radiation and extreme heat created by the explosions. The rocket also has chemical-fuelled rocket engines so that it can take off and land without polluting the surroundings with deadly nuclear fallout.

    Fan Works 

    Film — Live-Action 

  • Aeon 14: In Destiny Lost and its P.O.V. Sequel Know Thy Enemy, an AST fleet starts detonating megaton-range hydrogen bombs against their Deflector Shields to try and escape a black hole's gravity well.
  • Anathem: A spacecraft that travels between different dimensions uses an Orion-style propulsion system. This ship, the Daban Urnud, is discovered by observing the nuclear explosions used to modify its orbit.
  • Bolo: A Bolo is stranded in space after its transport is accidentally destroyed by friendly fire that was targeting an invasion fleet which also significantly damaged the tank itself. To get into action, the Bolo uses its Hellrails (Hellbores tasked specifically with shooting down spacecraft) to create what are effectively small-scale nuclear explosions to nudge it to where it needs to go.
  • Boomers by J. R. Dunn is an alternate history story where both the US and Soviets build Orion-drive "boomer" spacecraft.
  • Cepheide describes a ship with Orion propulsion as one of the most primitive and wasteful methods of interstellar flight, still only achieved by a tiny minority of all intelligent races in the universe. The ship is said to be the last relic of an unknown race exterminated by the dominant YiYiki (descendants of the humpback whales).
  • The Draka: In The Stone Dogs, Orion spacecraft are created during an arms race between the Domination of the Draka and the Alliance for Democracy, and used by both sides in their explorations of the solar system and as warships. The drive itself features as an improvised weapon in the book, being used to keep other ships at a distance.
  • Edison's Conquest of Mars has the Martians retreat by detonating a bomb underneath their Cylinder, propelling them back home. Since they don't have a Space Launch Cannon like the one they used to invade with, they waste a lot of the energy, necessitating that they use a bomb capable of leveling the entirety of New York and New Jersey states.
  • Eight Worlds:
    • The Golden Globe: The wreck of an Orion spaceship is converted to an interstellar starship.
    • Steel Beach sets several scenes near or within the bulk of the "Robert A. Heinlein," the aforementioned Orion-style ship, which was built and then abandoned when humanity lapsed into apathy for stellar exploration.
  • Eldraeverse: The basis of the space program, launched from a remote desert site to keep the fallout as low as possible. Even thousands of years after they switched to beanstalks that desert still glows in the dark.
  • Footfall: Humanity uses a ground-launched Orion drive spaceship in a last ditch effort to fight off the invading aliens, as it's the only way to get sufficient firepower into the orbitals. A crew member of the Archangel Michael memorably describes liftoff:
    God was knocking, and he wanted in bad.
  • Great Ship: The Orion Drive (referred to as a bomb drive) is a common form of propulsion where anti-matter or fusion rockets are too expensive or delicate. One of the main characters of Marrow, Pamir, was the captain of a liner equipped with an ancient bomb-drive.
  • The Hive involves the use of a ground launched Orion spacecraft by the People's Republic of China in a gamble to reach an alien artifact in orbit between Jupiter and Saturn before the crew of a spacecraft built by the United States and Russia can reach it first.
  • Junction Point: A nuclear drive is used by the ktrit'zal in order to escape the high gravity of their homeworld.
  • King David's Spaceship: Inhabitants of a planet that is to be re-admitted to the Empire plot to build the spaceship based on an Orion project concept in order to qualify their planet as a higher-developed, Class One Imperial world. However, this craft uses non-nuclear explosives.
  • The Land Of Crimson Clouds: This is called "photonic drive". A spaceship is semi-spherical, and its inner surface is covered with a super-mirrornote  that reflects everything allowing to use the momentum of light for propulsion. So basically, thermonuclear explosions under the mirror drive the ship forward. In the sequels mirrors are thicker, engines are smaller, ramscoops appear, certain side effects are discovered at relativistic speeds. This eventually leads to Casual Interstellar Travel as seen in the Noon Universe proper.
  • In Daniel Keys Moran's The Long Run, the main character, Trent, is in orbit around Luna and being chased by the bad guys. The pilot of his ship says that he is sure that they can get away, Trent says "Good", the pilot replies "Not really, it involves the Orion maneuver". Trent replies "Oh, no" to which the pilot responds "Oh, you have heard of it..."
  • Marooned in Realtime: Bobble technology makes this method of travel safe. Toss a timed nuke out of a spaceship, then activate a short-lived (and totally indestructible) bobble. The nuke will explode, shoving the bobbled ship away.
  • Olympos describes an Orion-style spaceship, designed by the Moravec machine race to emulate 21st century human technology.
  • Project Orion: The Atomic Spaceship 1957-1965 by George Dyson is a non-fiction book about the real research into Orion drives (see the Real Life section below). Dyson is the son of Freeman Dyson, who was involved in the project.
  • Starfire:
    • The Shiva Option: An arachnid homeworld is destroyed by converting several asteroids into Orion-drive starships and launching them at it.
    • Humanity's allies, the pseudo-feline Orions, take the naming of the concept as an honour, not knowing the technology was imagined before humanity ever left Earth.
  • Stephen Baxter:
    • Ark (2009): The starship Ark One is built to save a small group of people as Earth drowns under a global flood. It launches and performs the first phase of its mission using a version of Orion. This version is ground launched though owing to the situation (the entire planet is about to drown anyway) environmental concerns are set aside.
    • Manifold: Space has the main character piloting an Orion craft to a large blue ring situated just outside the Solar system.
  • Tricentennial: The Daedelus (or John F. Kennedy, or Leonid Brezhnev — apparently spaceships are also prone to renaming) is powered by nuclear bombs.
  • Troy Rising by John Ringo: Troy, a massive battle station ten kilometers wide made from a hollowed-out and inflated asteroid, adds an orion drive so that it can get to the Portal Network and go crush enemy alien fleets. Upon first seeing the Troy come through the gate, the aliens think it's been hit, only to suddenly realize it's actually the drive.

    Live-Action TV 
  • Cosmos: A Personal Voyage: This is mentioned as one possible design for a ship capable of crossing interstellar distances, along with the Daedalus.
  • The Expanse: The ubiquitous Epstein Drive is a laser-triggered nuclear pulse drive, though operating at a high enough pulse frequency to appear continous.
  • Space: 1999: In "Voyager's Return", there's a nuclear pulse-drive probe called Voyager One. The dangerous nature of its drive is a plot point.
  • Star Trek: The Original Series: "For the World Is Hollow and I Have Touched the Sky" features a generation ship, constructed out of a hollowed-out iron asteroid, propelled using "Orion class nuclear pulse engines" in which fission bombs were detonated in shafts. It appeared to have been traveling for about 10,000 years, and had traveled about 30 light years on its own power. Unfortunately by the 23rd century one of the tubes is damaged (or the weapons used just plain malfunctioned during a course change) and the ship is on a collision cause with an inhabited planet. As such the Enterprise finds itself fighting to save both planets by correcting the ships course.
  • Virtuality: Phaeton, Earth's first starship, is propelled by an Orion drive.

    Tabletop Games 
  • Rogue Trader: Rak'gol ships use "fission-pulse" drives, powered by atomic reactors. As such, their ships have high speed, but their maneuverability leaves much to be desired. Also, these drives irradiate the ship so much that other races can't stay inside of them for too long.
  • GURPS Spaceships has this as far and away the most capable non-superscience propulsion system at low TL, at the cost of extremely expensive fuel and substantial rear armor requirements. At TL 9 and above nuclear pulse drives using externally triggered reactions are the highest performing non-superscience rockets not requiring antimatter.

    Video Games 
  • ANNO: Mutationem: In the introduction, The Consortium attempts a Nuke 'em onto the Limen crater by launching air units with specialized Orion Drives to double the nuclear pulse propulsion at the point of impact.
  • Aurora (4X): Nuclear Pulse Drive is the second tier of researchable engines. Subverted as its no different than any other engines including Antimatter drives.
  • Kerbal Space Program:
    • Orion drives are available in a Game Mod, one of which is developed by the man behind the Atomic Rockets science fiction site, who details the struggles of coding one. On his first test fire of the drive with a 15kt warhead, the force of the explosion caused the command pod to blow off the top like an cork on a champagne bottle. When he changed the code to try to prevent this, the pod shot past the speed of light on the first test fire.
    • In the base game it's possible to use large amounts of decouplers as an insanely powerful propulsion system.
    • The sequel (KSP 2) plans to make the Orion Drive available in the stock game.
  • Sid Meier's Alpha Centauri: The sleeper ship is propelled by an Orion-type drive (probably the laser-fusion variant), the shield of which fails (almost certainly due to sabotage—the ship's captain was also assassinated at the same time) when the ship is almost at its destination, causing the passengers on the colony ship to splinter into factions.

    Web Originals 
  • Atomic Rockets:
    • The site has an article on how they work, and on the research that went into the "nuclear shaped charges" (codenamed Casaba Howitzer) that make it go. A tungsten "pancake" results in a beam of plasma (great if you want to use nukes in space, not so much if you want to use them to fly with). Conversely, a styrofoam (yes, really) "cigar" results in a wide wave of plasma, focusing 80% of the bomb's energy onto the pusher plate.
    • A related idea mentioned is "Nuclear salt water" engines. The propellant is just regular water with thorium salt dissolved in it. Once it's pumped out of the neutron-absorbing holding tanks, the salt goes prompt-supercritical, resulting in a nuclear explosion. The advantage is that it has the exact same power as an Orion drive, but it can keep the pumps on a lot longer. The disadvantage? If it gets shot in the gas tank, it'll explode.
    • In the "RocketCat's Universe" sample setting, Canada has a fleet of Orion drive warships.
  • In the "big enough rock" story, humans use a massive explosion to propel both the Earth and the Moon, one towards hostile aliens, the other towards a new habitable orbit.
  • Freefall: Discussed when the main cast is inadvertently trapped a few light-seconds away from Planet Jean with only one reactor (long-distance space travel requires two). Sam proposes an Orion drive in lieu of a second reactor, given the availability of a bombs factory that is largely inactive. Unfortunately, the two-reactor rule is for life support purposes rather than propulsion, and besides, the Savage Chicken isn't durable enough for more than one Orion pulse.
  • Orion Drive ships are used by all three major factions (the British Empire, the Russians and the Chinese) in the "Monarchy World" Alternate History by Tony Jones. They are launched from zones in each empire which were already radioactively contaminated by earlier nuclear disasters, so further contamination doesn't matter so much.

    Western Animation 
  • Ben 10: Ultimate Alien: The military calls them in to investigate the theft of components to an Orion Drive. Kevin immediately deduces that it's a nuclear bomb.

    Real Life 
  • Project Orion, the Trope Namer, which actually happened — although they never went full-scale for obvious reasons. The project eventually got canceled by an international treaty banning nuclear weapons in space.note  and also with Kennedy being really scared by US Air Force's proposals to weaponize the drive. One of these proposals was the 4000 ton Orion Battleship, equipped with six hypersonic landing boats, a secondary armament of three 5 inch naval guns and five 20mm CIWS turrets and a primary armament of 500 twenty megaton conventional nukes and an unspecified ammount of Casaba Howitzers: weaponized version of Orion Drive bombs. The other proposal was even more terrifying: an unmanned version of the Orion Battleship with much of its crew and weapons compartment replaced with a massive 3 gigaton hydrogen bomb — the largest ever seriously proposed by any nation so far, and a veritable Doomsday Device.
  • Project Daedalus, which was a conceptual design thought up by the British Interplanetary Society, which wasn't worked upon since it's not yet possible. Instead of bombs, it would use a less hamfisted approach, with lasers being focused on small deuterium-tritium pellets to create small fusion detonations - a process which is indeed being studied as a means of peacefully harnessing fusion energy - but the basic idea of using pulsed explosions remains the same.
  • Project Longshot, which was basically Project Daedalus if it were (A) allowed to decelerate on the way in to Alpha Centauri, and (B) more realistic about the difficulties of using engine power to run its own electrical systems.
  • Allegedly, the unexpected firing of a 900kg steel lid from the top of a nuclear test chamber into the sky at 60km/s was inspiration for some of the Orion design. If it survived its flight it would have been the first (and only) nuclear launched man made object in space. It probably burnt up before it exited the atmosphere though. Experimental designer Dr. Robert R. Brownlee described the best estimate of the cover's speed from the photographic evidence as "going like a bat out of hell!"
  • The Medusa spacecraft design, brought to you by the same folk who dreamed up the Daedalus above, was a 90s update that was effectively a nuclear sail. The design would be lighter and more efficient than an Orion-based ship.
  • Lew Allen's Balls were the original inspiration for Project Orion. They were used to test the effects of point-blank nuclear blasts on various materials. Stainless steel balls within a few feet of the detonation point of small test nukes were found, with minimal damage, embedded in the desert floor thousands of feet away. (This began a chain of reasoning about using the shock wave from a nuke as a source of propulsion that ultimately produced the Project Orion proposal.)

Alternative Title(s): Nuclear Pulse Propulsion