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> nuclear is unfashionable at the moment It's more than that - this isn't just hippies, it's every major power on the planet. To fly Orion you have to put hun

> nuclear is unfashionable at the moment It's more than that - this isn't just hippies, it's every major power on the planet. To fly Orion you have to put hundreds of nuclear explosives in orbit and pinky-swear that you're not going to use them to obliterate your enemies. Nobody is going to accept that. Orion's a fun paper rocket but will never be more. Engineers and they "yay nukes!" crowd will drag it out every couple of months for a repost, though.

jessriedel 10y ago
> To fly Orion you have to put hundreds of nuclear explosives in orbit and pinky-swear that you're not going to use them to obliterate your enemies. To reiterate berntb's point: Every nation who has the ability to do this already has ICBMs that can deliver nukes anywhere on the planet in 20 minutes. So what difference does this make?
- DennisP 10y ago
  True, but we still have a treaty that prohibits bombs in orbit, because they'd reduce the warning time enough to threaten deterrence. Maybe one day we can launch Orion from Mars.
  - maxerickson 10y ago
    Drive it to Earth, have lots of bombs left. From a strategic point of view, what's the difference between building on Mars and building it in orbit? Obviously there is a difference because the hostile faction has to seize control of it and move it to Earth, but once they do that, the calculation becomes the same. Do you commit to obliterating them the second they start moving it to Earth?
    - masklinn 10y ago
      Best case scenario, Mars is 55 million kilometres from earth. Even using a ridiculous engine going full blast the whole way (in which case your payload will probably disintegrate when it hits the atmosphere) you won't get the transfer time under a month. If you want to actually deliver your payload in a useful manner you'll need twice that at the very least. 2+ months is a long lead time, and the engine you'll need will make the craft impossible to miss. What's the difference to building it in orbit? Building it in earth orbit you're dropping it from under 500km and your assembly makes 10~20 orbits a day, you can deliver it quickly at pretty much any time. The former allows countermeasure, the latter not really.
      - maxerickson 10y ago
        I'm talking about just flying the entire Orion ship to Earth, loaded with propellant bombs. Sure, you can try to take it out during the journey, but that may be complicated by it being the highest g ship in existence for the Mars-Earth distance. Once/if it arrives, you have the same strategic problems you have if you build it in orbit.
        masklinn 10y ago
        > I'm talking about just flying the entire Orion ship to Earth, loaded with propellant bombs. Er… yes? > Sure, you can try to take it out during the journey, but that may be complicated by it being the highest g ship in existence for the Mars-Earth distance. That's not really a complication, it's still taking months to make the trip, and while it might be "the highest g ship in existence" that's linear acceleration, it's not a nimble ship performing a tailside in space to avoid projectiles. > Once/if it arrives, you have the same strategic problems you have if you build it in orbit. With the pretty damn big difference that you've had several months head start knowing the think was incoming at high speed instead of it just dropping of your head more or less instantly.
        maxerickson 10y ago
        Er… yes? Sorry, I didn't understand why you were talking about bothering to do that and then crashing it into the atmosphere.
        masklinn 10y ago
        If you're crashing it into the atmosphere you're not delivering anything, the ship and its payload will just disintegrate, possibly bouncing back in the process. Even if the payload does detonate on impact, the only purpose an explosion at atmospheric boundaries would have would be EMP.
        Pinckney 10y ago
    - smithy44 10y ago
      Empress Sato!!
berntb 10y ago
If you read the book (by Freeman Dyson's son) or even the wikipedia page, you'd know the bombs were quite specialized. And it would certainly be possible to allow some verification (the trigger would not need inspection, that would probably be the really sensitive part, from a technology secrets point of view). [Edit: The bombs would be directed, throwing light weight molecules up against the pusher plate.] Also, there is no direct lack of ways to distribute nuclear devices to capitals today, for the countries able to build an Orion. Compare that with the possibility to launch enough material to e.g. start on getting an industrial infrastructure going outside the atmosphere.
- arethuza 10y ago
  The "directed" bomb designs used tungsten - in "The Curve of Binding Energy" I seem to remember there is a comment that they were spectacularly good at digging tunnels but I don't know if that was a theoretical prediction or an empirical result.
  - berntb 10y ago
    I meant that the material thrown at the plate were planned to be plasma of more lightweight materials, iirc. (That is different than how to make an atomic bomb directed.) I haven't seen any real details of directed bomb design discussed. Thanks for the pointer to that book.
  - madaxe_again 10y ago
    If you consider that it was contemporaneous with plowshare, that makes sense - likely a degree of shared research.
- grkvlt 10y ago
  Any mechanism that can propel a starship to 0.13c is going to make your day unpleasant if it is pointed at things you have a particular fondness for. Favourite pets, cities, aircraft carriers, that sort of thing.
  - berntb 10y ago
api 10y ago
Even worse: the EMP from an Orion launch would fry a lot of satellites. It's not a practical design for use anywhere near... anything. You could launch one from the far side of the Moon, but if you have that kind of space presence there are better engine designs. Some have been posted elsewhere in this thread.
- mikeash 10y ago
  Yes, Orion looked a lot more attractive back before civilization became reliant on huge quantities of sensitive electronics in near-Earth space.
- adrusi 10y ago
  Stupid that satellite electronics don't have more radiation shielding. We can refrain from nuclear detonation in orbit all we want, but the sun could still EMP us at any moment. Maybe it's expensive to lift heavy shielding into orbit, but it's more expensive to deal with the consequences of satellite systems outages and repairing/replacing broken equipment.
maverick_iceman 10y ago
Anything that can accelerate a starship to a velocity of ~0.1c can have devastating consequences if pointed to earth. Just like planes can be used to destroy skyscrapers. Chicken littles notwithstanding, having a much faster mode of transport is worth the risk.
- jandrese 10y ago
  On a side note, this is why Independence Day and other interstellar alien invasion movies don't make much sense. The amount of resources necessary to move between solar systems in an even slightly reasonable timeframe is orders of magnitude larger than what you need to obliterate all life on the planet in just a few seconds. The idea that you could meaningfully fight back against an interstellar traveler is silly.
- binarytransform 10y ago
  It may be worth the risk but that doesn't change the fact that what you refer to as "Chicken Littles" represent power players in an intractable political dynamic. The only way this kind of cooperation happens is when humans move past current notions of nation states and begin to think strategically as a species.
  - diamondlovesyou 10y ago
    Not if an independent organization (think a Corp, not a gov) is the party responsable. They would have no incentive to do such a thing, in fact they would have a negative incentive. Too bad nuclear tech is basically too regulated for any non governmental organization to experiment inexpensively, not to mention the other nontechnical issues.

jessriedel 10y ago

> To fly Orion you have to put hundreds of nuclear explosives in orbit and pinky-swear that you're not going to use them to obliterate your enemies. To reiterate berntb's point: Every nation who has the ability to do this already has ICBMs that can deliver nukes anywhere on the planet in 20 minutes. So what difference does this make?

DennisP 10y ago
True, but we still have a treaty that prohibits bombs in orbit, because they'd reduce the warning time enough to threaten deterrence. Maybe one day we can launch Orion from Mars.
- maxerickson 10y ago
  Drive it to Earth, have lots of bombs left. From a strategic point of view, what's the difference between building on Mars and building it in orbit? Obviously there is a difference because the hostile faction has to seize control of it and move it to Earth, but once they do that, the calculation becomes the same. Do you commit to obliterating them the second they start moving it to Earth?
  - masklinn 10y ago
    Best case scenario, Mars is 55 million kilometres from earth. Even using a ridiculous engine going full blast the whole way (in which case your payload will probably disintegrate when it hits the atmosphere) you won't get the transfer time under a month. If you want to actually deliver your payload in a useful manner you'll need twice that at the very least. 2+ months is a long lead time, and the engine you'll need will make the craft impossible to miss. What's the difference to building it in orbit? Building it in earth orbit you're dropping it from under 500km and your assembly makes 10~20 orbits a day, you can deliver it quickly at pretty much any time. The former allows countermeasure, the latter not really.
    - maxerickson 10y ago
      I'm talking about just flying the entire Orion ship to Earth, loaded with propellant bombs. Sure, you can try to take it out during the journey, but that may be complicated by it being the highest g ship in existence for the Mars-Earth distance. Once/if it arrives, you have the same strategic problems you have if you build it in orbit.
      - masklinn 10y ago
        > I'm talking about just flying the entire Orion ship to Earth, loaded with propellant bombs. Er… yes? > Sure, you can try to take it out during the journey, but that may be complicated by it being the highest g ship in existence for the Mars-Earth distance. That's not really a complication, it's still taking months to make the trip, and while it might be "the highest g ship in existence" that's linear acceleration, it's not a nimble ship performing a tailside in space to avoid projectiles. > Once/if it arrives, you have the same strategic problems you have if you build it in orbit. With the pretty damn big difference that you've had several months head start knowing the think was incoming at high speed instead of it just dropping of your head more or less instantly.
        maxerickson 10y ago
        Er… yes? Sorry, I didn't understand why you were talking about bothering to do that and then crashing it into the atmosphere.
        masklinn 10y ago
        If you're crashing it into the atmosphere you're not delivering anything, the ship and its payload will just disintegrate, possibly bouncing back in the process. Even if the payload does detonate on impact, the only purpose an explosion at atmospheric boundaries would have would be EMP.
        Pinckney 10y ago
  - smithy44 10y ago
    Empress Sato!!

berntb 10y ago

If you read the book (by Freeman Dyson's son) or even the wikipedia page, you'd know the bombs were quite specialized. And it would certainly be possible to allow some verification (the trigger would not need inspection, that would probably be the really sensitive part, from a technology secrets point of view). [Edit: The bombs would be directed, throwing light weight molecules up against the pusher plate.] Also, there is no direct lack of ways to distribute nuclear devices to capitals today, for the countries able to build an Orion. Compare that with the possibility to launch enough material to e.g. start on getting an industrial infrastructure going outside the atmosphere.

arethuza 10y ago
The "directed" bomb designs used tungsten - in "The Curve of Binding Energy" I seem to remember there is a comment that they were spectacularly good at digging tunnels but I don't know if that was a theoretical prediction or an empirical result.
- berntb 10y ago
  I meant that the material thrown at the plate were planned to be plasma of more lightweight materials, iirc. (That is different than how to make an atomic bomb directed.) I haven't seen any real details of directed bomb design discussed. Thanks for the pointer to that book.
- madaxe_again 10y ago
  If you consider that it was contemporaneous with plowshare, that makes sense - likely a degree of shared research.
grkvlt 10y ago
Any mechanism that can propel a starship to 0.13c is going to make your day unpleasant if it is pointed at things you have a particular fondness for. Favourite pets, cities, aircraft carriers, that sort of thing.
- berntb 10y ago

api 10y ago

Even worse: the EMP from an Orion launch would fry a lot of satellites. It's not a practical design for use anywhere near... anything. You could launch one from the far side of the Moon, but if you have that kind of space presence there are better engine designs. Some have been posted elsewhere in this thread.

mikeash 10y ago
Yes, Orion looked a lot more attractive back before civilization became reliant on huge quantities of sensitive electronics in near-Earth space.
adrusi 10y ago
Stupid that satellite electronics don't have more radiation shielding. We can refrain from nuclear detonation in orbit all we want, but the sun could still EMP us at any moment. Maybe it's expensive to lift heavy shielding into orbit, but it's more expensive to deal with the consequences of satellite systems outages and repairing/replacing broken equipment.

maverick_iceman 10y ago

Anything that can accelerate a starship to a velocity of ~0.1c can have devastating consequences if pointed to earth. Just like planes can be used to destroy skyscrapers. Chicken littles notwithstanding, having a much faster mode of transport is worth the risk.

jandrese 10y ago
On a side note, this is why Independence Day and other interstellar alien invasion movies don't make much sense. The amount of resources necessary to move between solar systems in an even slightly reasonable timeframe is orders of magnitude larger than what you need to obliterate all life on the planet in just a few seconds. The idea that you could meaningfully fight back against an interstellar traveler is silly.
binarytransform 10y ago
It may be worth the risk but that doesn't change the fact that what you refer to as "Chicken Littles" represent power players in an intractable political dynamic. The only way this kind of cooperation happens is when humans move past current notions of nation states and begin to think strategically as a species.
- diamondlovesyou 10y ago
  Not if an independent organization (think a Corp, not a gov) is the party responsable. They would have no incentive to do such a thing, in fact they would have a negative incentive. Too bad nuclear tech is basically too regulated for any non governmental organization to experiment inexpensively, not to mention the other nontechnical issues.