Project Orion: The Starship Propelled by Nuclear Bombs

in space •  3 years ago  (edited)

One of the most outrageous, seemingly impossible things I could tell you that is nevertheless true is "The United States has had the technology needed for interstellar flight since the mid 1970s." That can't be true, surely? Why then aren't there starships on their way to exoplanets as we speak? As usual, the devil is in the details.

The devil, in this case, is the atomic bomb. Following the Trinity tests, it was noticed that one of the metal test objects was virtually unharmed in some places by the blast. After later study it was determined that this happened because the object happened to have graphite oil on those spots. The oil absorbed the intense heat of the nuclear conflagration, boiling away in the process but leaving the metal underneath wholly unblemished.

News that there existed a relatively simple way to insulate metals against even close range nuclear blasts electrified engineers of the day, including Freeman Dyson. George Dyson, Freeman's son, gave an excellent TED talk about his father's involvement in the Orion project and the astonishing feats of manned spaceflight it could have made possible by now.

The concept was at once simple and wildly audacious. Small coffee can sized nuclear "bomblets" would be rapid fired by a railgun out the back of the Orion vessel. They would pass through a narrow hole in the "pusher plate", the shock absorbing barrier that would catch the brunt of the resulting nuclear blast. The vessel would then ride that blastwave forward. The next bomblet's explosion would add momentum to the vessel, then the next and so on, with pores in the pusher plate re-applying a new thin layer of protective graphite oil between each blast.

It was designed during the "anything goes" era of nuclear technology, largely on account of the cold war. However insane and over ambitious this might seem, the math checks out. It is absolutely feasible from an engineering standpoint. Just not from a political one. The Partial Test Ban treaty with Russia, which prohibits upper atmospheric nuclear detonations, resulted in the cancellation of the Orion project. It was then indefinitely mothballed, waiting for a more favorable political climate.

It did not especially help that the version of Orion shown to president Kennedy was armed to the teeth with nuclear missiles and howitzers. They severely miscalculated what sort of man Kennedy was when they presented him with that hypermilitarized mockup.

It's a terrible shame, too. Nuclear pulse propulsion makes it possible to achieve the speeds necessary to cross the vast distances between stars in under a human lifespan. Specifically, using modern thermonuclear bomblets, it would be possible to accelerate one of the larger Orion concept craft to one tenth the speed of light. At that speed, it would take 47 years to travel from our own solar system to Alpha Centauri, including the time needed to decelerate at the destination.

Orion can also be launched from the Earth's surface. It makes possible unprecedented surface to orbit payload capacities. You could basically send up an entire orbital colony in one launch. Some plans called for the pusher plate to be made of uranium so colonists could slowly cannibalize it for use in the colony's reactor.

This interested NASA intensely. They designed their own conceptual nuclear pulse propelled spacecraft, much smaller and more modest than Orion, intended to be assembled in orbit rather than launched from Earth. This would evade the partial test ban treaty but severely limit the size of the vessel, hampering its utility. Still, having a high speed reusable interplanetary shuttle, never meant to land on any planet, would make routine manned missions to any solid mass in the solar system a breeze.

Lament, then, for the starship that never was. Current approaches to nuclear propulsion favor nuclear thermal rockets, as the acceleration profile of nuclear pulse is very hard on the astronauts. To call it a "bumpy ride" would be a severe understatement, and general (appropriate) wariness of nuclear explosives turn many off to the idea.

If we dig Orion out of early retirement, it will likely be out of desperation. Orion's ability to launch an immense payload from Earth to orbit, then to accelerate it to a significant fraction of the speed of light gives us a powerful potential weapon against incoming asteroids. It is perhaps the only weapon we could leverage that, on short notice, would give us a fighting chance against that sort of threat.

It is also the only way we could get enough of humanity off Earth in a hurry to save our species if it turned out that the asteroid can't be stopped. The largest Orion designs, at 4,000 tons, could easily include all of the equipment necessary to grow a self sufficient food supply, to recycle waste water indefinitely, and in all other ways to keep the occupants alive for decades or even centuries.

So, the capability is there. Let's hope we never have to use it, and that if Orion vessels ever fly, it's because we pulled our heads out of our asses and decided to get serious about expanding our species into space. I pine for a future in which Orion vessels putt putt putt between destinations within the solar system setting up colonies and trading resources, while Orion probes are sent to promising exoplanets to get a closer look.

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I wonder what would be the g load on the astronauts after each blast ?

It is discussed in the Project Orion page on wikipedia - 100g for unmanned, 2G for humans. the pusher plate would be on pistons to absorb and buffer the shock.

Why go nuclear when we can do without the radiation? If we really have to go I get it but before then it doesn't really look like a viable option to me.

Radiation is already everywhere in space. If you mean launching from Earth, I feel you, but the lifting capacity made possible by the raw power of nuclear bombs is second to none. It should be fine if they only launched from existing nuclear bomb test sites.

This project was a key part of the end of season one of the Television show Hunters. :)

Oh man! This is such an exciting post for me. I had heard a tiny bit about propelling spacecraft with nuclear detonations but didn't know much about how it would work. This is exciting and it is so ridiculous that we aren't working on building probes with this technology and sending them off to exoplanets like you said. I get that people don't want it to be launched with that technology but the spacecraft was lifted with our current rocketry and then when it was away from Earth the nuclear propulsion system could be activated to take it to the closest star systems. It is unbelievable we aren't working on this. Can we please stop all the stupid wars and just focus our attention on this kind of stuff? PLEASE

Given the probe could send photos back to us within a couple decades, just imagine yourself as an old man seeing the first close up pictures of an Earthlike exoplanet with fluffy white clouds and big blue oceans.

Yeah I can imagine it! I'm sure you know a lot more about it than me but I got super excited about laser propulsion and I think with it we would be able to send small probes at an even more significant fraction of the speed of light. The issue becomes the power to then transmit the signal back on such a small little probe. It almost made me think we could send probes and get pictures back within a few decades. The scenario you posted where there would be a situation where Earth had to be left and we were all on these star ships living and trying to find a new home is crazy to think about. It sort of reminds me of Battlestar Galactica! I'm so glad I'm following you now or I probably would have missed this post.

the title already thought that the description of the new cryptocurrency :)

Orion is a great project ! I also have heard of another way to propel the vessel, it uses black holes but I don't know how they would use it, still they would create the tiny black hole thanks to very very very veryyyy powerful lasers to create it and then the black hole would evapore it in seconds but it would be enough for the vessel to absorb huge quantity of energy and thus reach a maximum speed of 60 % of the speed of light. That way the crew would reach the nearest star in only 7 years !

you know, we don't know how to create black hole, don't you ?

The spaceship is coming. The spaceship is coming.

If the idea is economically and technically feasible, why nobody tried to involve the Chinese, Russians and Europeans for this project like they have done for the international space station?

Thanks for sharing this, that was a cool read man, keep it up^^

Awesome post! I've always wanted to know more about project Orion but never took the time to sit down like this before. Thanks for this! Upvoted and followed!

great information thanks

That would be a very cool way to get rid of some of the most insane, and expensive, weaponry on the planet! Like it!

The ISP of Orion is really not as amazing as it seem; the ISP actually is less than a nuclear powered VASIMR engine. Which means that you could get interstellar without the bombs.

VASIMR can't get you from surface to orbit however.

true enough - but if you build an interstellar starship on a planet, you've already messed up.

An interesting video was made by Scott Manley about Project Orion, and demonstrated it (kind of) in Kerbal Space Program. Quite interesting.

Cool, a good friend of mine worked on this project with Freeman Dyson, he also worked on the neutron bomb at livermoore, he died last year. This post made me think of him.