Nuclear Bombed Propulsion

One of the things I wanted for Christmas was a clear path for a return of the US manned space program. I’m still waiting. Then I read about Project Orion and thought that elements of it could be used to get our astronauts flying on US-made rockets again.

Project Orion was proposed and studied in 1958, though the concept actually dates back to 1947. It’s quite a genius concept and it would produce a rocket system that would have both large amounts of thrust and a high specific impulse. Traditional rockets will have one or the other. Specific impulse is a measure of how much thrust can be developed from a given mass of fuel. Traditional rockets must carry large amounts of fuel to develop the thrust required, and therefore have a small specific impulse.

Not Orion. Instead of having to carry fuel and oxidizers, it would carry nuclear bombs.

Yes, you read that right.

The Orion craft would be launched with traditional rockets that would fall away after the craft had reached an altitude where it would be safe to start dropping the nukes. A small nuclear bomb would be dropped behind the rocket and explode. A plate on the bottom of the craft would transfer the energy from the explosion into motion of the rocket.

The system showed great promise, and some huge downsides. The altitude the nuclear devices could be used at would have to be high enough that there wouldn’t be an issue with EMP and fallout on Earth. The southeastern United States would be in a prayer vigil during each launch hoping that nothing went wrong and the nuclear devices detonated or were otherwise compromise.

On the up side was a virtually limitless expandability of the system. Unlike a traditional rocket where adding stages and weight quickly becomes a game of diminishing returns, the high specific impulse allows for relatively painless expansion.Some concept sketches show humongous spacecraft that could carry everything astronauts would need to live and work on Mars or in space for years while travelling to Saturn or Jupiter. Some concepts even scaled it up for interstellar travel.

The project was officially cancelled in 1963, austensibly because of the Partial Test Ban Treaty. However, the idea of nuclear pulse propulsion has come up time and again, and some conspiracy theorists believe NASA and/or the Air Force have the plans in place to build one of these things to take out an Earth-bound asteroid.

[Image Credit: Adrian Mann]

  • texlenin

    It's only one measly megaton at a time….
    You forgot to mention that the bottom of the
    pusher plate was to be covered by a oil
    spray, like a giant frying pan!
    "Mars by '65, Saturn by '70"

  • jeepjeff

    Project Orion is one of my favorites. It really is too bad it got cancelled, even if I know why it never got off the ground. Actually, it's pretty simple:
    Awesomeness: A+++
    Environmental Impact: F-
    The idea is awesome beyond normal reasoning ability. However, that's all I've got to justify its existence. Not even I can justify just how dirty these would be to launch. I remember reading that it would have taken 250 low-yield fission bombs to get into orbit. 250 bombs in the atmosphere. Every launch.

    Now, if we could figure out fusion only weapons, I'd be hollering to build this just to see one launched.

    • The Professor

      Yes, I'm a project Orion fan from way back too. The simplicity and efficiency are marvelous, it's just the teensy little problem of hoisting a staggering number of nuclear devices high into the atmosphere, then setting a few off to reach space. Even I would think three or four times about that, even going by the "Safety Third" standard. If the spaceship could be constructed in orbit, or better yet the asteroid belt, and ship the nukes up unassembled and in small batches, it's almost thinkable.
      The science fiction novel by Larry Niven and Jerry Pournelle, entitled Footfall, used a Project Orion craft to stop an alien invasion of Earth. It's a pretty good read.

      • jeepjeff

        Adding Footfall to my list. (I'm familiar with Niven and Pournelle, I just hadn't heard of Footfall.)

        It's one of those things where if you have me questioning the idea, you aren't going to get very far. I get pretty starry-eyed about nuclear power technology and would happily build a pebble bed in my backyard but for the lack of readily available fissile materials.

        Surprisingly enough, well designed nuclear weapons are quite safe to transport. If the timing on the high explosive lenses are off, it will fizzle at worst. If you use a hollow pit, filling it with just about anything (steel chain is often used) will prevent the bomb from going off as well. The high explosive lenses end up being the most dangerous part, as it is difficult to make them not explosive. Though, given the stresses of launch, packing the lenses away from the pits is probably a good idea (also, packing the lenses somewhere where they are least likely to critically damage the vehicle during launch would be top of my list).

        You could easily get me behind building and launching them from the moon. The only problem is getting enough of a base there for it to be possible. Also, there's all the ninnies who get their panties knotted up when you just launch a wee bit of plutonium into orbit. (Fortunately, they may be ignorable. They were last time around.)

        • The Professor

          Oh my, yes, regarding the launching of RTGs, I find the self-urinators' arguments unpersuasive and tiresome. 'What if! What if! What if!' They build strawmen all day, but refuse to regard the engineering. Wankers.
          The transport of nuclear devices has rarely troubled me (although the DOD does seem to try to, occasionally). If an accident were to happen, as you say, the device itself wouldn't detonate, but it would make a very nasty mess to clean up. That would be my main concern about lifting a bunch of them into orbit. Our (and everyone else's) rockets do occasionally explode during the launch and lift stages, and it would take some very good packaging to prevent an ecological disaster if that should happen with a load of nukes as payload.
          But an assembly base on the Moon sounds like a great idea. I'd much rather see us go back to the moon and do something useful, rather than go fucking off to Mars on a lark.

          • jeepjeff

            Ok, you are right, rockets still explode (regularly), so we'd need to be careful, but I tend to have faith in the engineers on such a project. Admittedly, most of the engineering that has gone into launching nuclear weapons on rockets doesn't necessarily overly concern itself with safety…

            I'm a big fan of fucking off to Mars on a lark, but I'm an even bigger fan of us to get back to building spaceships for canned monkeys to go anywhere. So, we can still be friends. (Also, a moon launched Orion vessel would be able to make us both happy.)

          • The Professor

            Oh, I'm not against going to Mars eventually, I just want the tech that's going to keep our astronauts alive tested first, preferably a few million miles closer to home, and in a harsher environment than they will experience on Mars. I don't want our young boys and girls to die on an alien world just because someone had a bug up their butt to get to Mars in a big hurry. Mars isn't going anywhere.
            I'd also love to see us make ships that could ferry us all around the solar system in a reasonable amount of safety. When we finally get fusion to work for us, that dream will start to become real, and I can't wait. I'll probably be dead before it happens though. Damned decrepit human bodies…
            Oh yes, a moon launched Orion would be a wonderful thing to see.

      • I saw the headline and came here to post something about Footfall. Now I get to leave happy. And impressed that someone beat me too it.

        I saw a History/Discovery channel show one time discussing resurrecting Project Orion using giant pulse lasers, on the ground, fired at the bottom of the plate as the impulse instead of nukes.

        • The Professor

          It's always good to find another Niven/Pournelle fan. The science in their stories, and especially in Niven's solo works, is usually fun to play with. I've been reading Larry Niven's stories since the late '60s and Neutron Star.
          I've seen demos of small (3 or 4 inches across) craft being launched using lasers, but nothing the size of an Orion vessel. That would take some big freaking lasers to provided enough thrust. It would have to be a scary thing to be a pilot of an Orion-type vessel: what do you want under yer butt? Giant lasers or little nukes?

          • jeepjeff

            Well, for the same amount of thrust, they'll both blow you into the same number of teeny, tiny pieces.

      • Charles_Barrett

        Niven/Pournelle's Footfall also came leaping into my mind for this thread. The downside for the launch vicinity is unfortunate, but preferable to alien enslavement/extermination.

        • The Professor

          Yeah, a bad time to live in Seattle, for sure. Have you ever read The Mote in God's Eye by those two? It's one of my favorite books.

          • Charles_Barrett

            Absolutely love all of their collaborations. Lucifer's Hammer was great to read while living in the L.A./San Fernando Valley/Burbank area, as the landmarks and local geography is so vividly described. Sometimes I think Oath of Fealty is eerily prescient; with Google and Smart Phones, we are approaching the scenario described in the Todos Santos Independency.

            I also am a fan of the Ringworld books and their same-reality offshoots by Niven.
            Jerry Pournelle was one of my favorite Personal Computing columnists back in the day ("Chaos Manor" and BYTE magazine). Now I'm showing my age, even though I was a precocious youth… đŸ˜‰

          • The Professor

            Our tastes in SF literature seem to rather similar, as I have all of those books on my overloaded bookshelves too. Niven's Known Space series of stories are some of my favorites, and it's good to see new authors writing stories for that universe. The first time that I read Ringworld I was boggled trying to imagine the scale of the structure and the things on it. Great fun, but I hope that we never spot one around a nearby star.
            Man, I haven't thought about Pournelle's Byte column in many years, but I used to read that too. I wasn't youth back then, but the old bod worked a helluva lot better than it does now.

  • coupeZ600

    The first I can remember hearing about this project was just recently on NPR when they had a show about all the crazy things the scientists wanted to do with their new toy back then. My favorite was the idea to set off a nuke on this side of the Moon, so for weeks, no matter what the phase, everyone all over the world could look up at night and see what bad-asses we were.

    • The Professor

      Hmph. I never heard of the plan to set off a nuke on the Moon, but it doesn't surprise me in the slightest. What does surprise me is that they didn't do it. The DOD has a real complex regarding the size of their collective penis.

      • texlenin

        Speaking of the DoD and wacky projects that
        would be just bad for everybody, has anybody
        done an article on 'The Flying Crowbar' aka
        The SLAM project?

  • Number_Six

    Neal Stephenson's excellent 'Anathem' also makes mention of this type of propulsion. Highly recommended, if wordy and in need of a good editor (like most of his latest).

  • Mad_Hungarian

    Unless there is some way to make the bomb explosions very directional, this seems like a ghastly inefficient way to push a rocket into space. When the bombs explode behind/under the spacecraft, won't a lot of the resulting energy go off in various directions other than pushing against the plate on the spacecraft? There must be some more efficient and less messy way to use fission to power a spacecraft. In other words, some kind of fission engine on board the craft.

    • ademrudin

      A) Orion planned to use nuclear "shaped charges", that would not simply dissipate energy in a spherical fashion. The Isp is actually quite impressive.

      B) Yes, there's a less messy way: NERVA. I don't know enough to comment on relative efficiency, but note that NERVA still required reaction mass (generally liquid hydrogen), whereas Orion is propelled purely by the fission energy. On the other hand, Orion had to lug around the pusher plate, shock absorbers, plate oiling system, etc…

  • ptschett

    I've loved Orion since I stoleread my mom's copies of Pournelle's A Step Farther Out and Niven/Pournelle's Footfall.

    Apropos book recommendation:
    <img src=",204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU01_.jpg&quot; width="300">

    It's been a while since my last re-read, but IIRC one of the things that scared some participants the most was how clean and efficient they thought they could get the pulse units to be, and how those enhancements could be applied to military use of nuclear weapons.