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> This sounds significantly more feasible than nuclear pulse propulsion ("project orion" style) which I used to think was the only feasible approach to get to a

> This sounds significantly more feasible than nuclear pulse propulsion ("project orion" style) which I used to think was the only feasible approach to get to another star. I still carry a torch for project Orion, it's impossible to not love. * Feasible 50 years ago, not 50 years from now. * No ultra lightweight fancy space age materials, steel and lots of it. * Seriously, lots of it, let's launch a battleship to to Mars, * or Jupiter, * or Alpha Centauri. * Gives everyone something way better to do with all those nuclear bombs they have laying around.

marcosdumay 1y ago
> it's impossible to not love As an idea, yeah. But if somebody actually tried to build it, the entire world would oppose for very good reasons. Still, it's something that maybe we should build on space (outside of Earth's magnetic field).
randallsquared 1y ago
> Gives everyone something way better to do with all those nuclear bombs The counterpoint there is it gives lots of reasons to make so many more, increasing proliferation worries. However, there's an SF novel that just came out that features nuclear pulse: Fenrir, by Ryk Spoor and (posthumously) Eric Flint. I enjoyed it.
- pavel_lishin 1y ago
  I should re-read Footfall, by Larry Niven. Quite a few banger lines in there.
  - m4rtink 1y ago
    Orion drive is one long line of bangers by definition! ;-)
- eszed 1y ago
  My favorite SF along those lines is King David's Spaceship, by Jerry Pournelle. https://en.m.wikipedia.org/wiki/King_David%27s_Spaceship https://en.m.wikipedia.org/wiki/King_David%27s_Spaceship
- MadnessASAP 1y ago
  Yeah, if I'm being really honest, I don't want to give anyone an excuse to put a 1000+ nuclear bombs in orbit. Plus the few dozen you'd have to detonate in quick succession to even get it above the karman line.
PaulHoule 1y ago
The electron beam ignition they talked about doesn't work. Heavy ion probably does https://en.wikipedia.org/wiki/Heavy_ion_fusion https://en.wikipedia.org/wiki/Heavy_ion_fusion but the accelerator needs like 100 barrels that are each 1 km. Maybe you can build a generation starship with that but whatever it is it's going to be big.
hermitcrab 1y ago
I once spoke to Freeman Dyson at a book signing and asked him if Orion would work. He said he thought it would. And I asked him if it should be launched. He said probably not (IIRC due to the amount of radiation that would be put into the atmosphere).
- jerf 1y ago
  It is almost the epitome of steampunk romance. Launch an entire mid-20th century city and economy into space! And it might even work! But, yeah, you probably don't want to be launching these routinely. People generally badly underestimate the number of nuclear explosions that have been set off on Earth and overestimate the badness of nuclear explosions. Putting one or two of these into orbit might be justifiable. It's certainly not a bad emergency plan to have in your pocket in case of emergencies. But you still certainly wouldn't want an entire industry routinely lighting these things off. Still... the romance of it all...!
  - m4rtink 1y ago
    While the Orion drive indeed works perfectly fine in atmosphere - or actually even better than in vacuum - no one says you need to launch them from the ground. While it would be preferable due to the immense weight, you can either lift it by conventional means or possibly build it from local resources in the long run. Once in space Orion is much less problematic & might be even easier to dock and maintain than normal nuclear thermal rockets, where the unshielded reactor will just put out insane amounts or radiation in all directions outside of its shadow shield. Correctly engineered pusher plate should be much easier to deal with.
    - jerf 1y ago
      Having to lift them via some other means first eats away almost all their advantage. However I believe your point holds more generally for nuclear-based space propulsion. That we fear "NUKULAR!" by about two to three orders of magnitude more than is justified has kept us from having halfway decent space travel for at least a good two decades, most likely. There are a number of nuclear propulsion mechanisms that would make things like going to Mars halfway feasible instead of flights of fancy, or doing science missions in months instead of years or even decades, but people hear that you're thinking of lifting nuclear material into space and all rationality goes flying out the launch window. Nuclear is so bad that it basically reaches out through outright magic and guarantees explosions and there's no conceivable amount of preparation that could be done in people's minds to prevent the evil radiation!!!!1! from escaping and eating people's puppies. The funny thing is that even so quite a bit of nuclear material has been lifted into space, but hearing that doesn't make people go "oh, well, maybe it's less dangerous than I thought". I mean, I know this isn't the safest stuff in the world but I sure hope all that anti-nuclear propaganda in the 20th century actually did help prevent nuclear war because it has certainly had massively negative impacts in energy generation, environmental damage, space exploration, and who knows what else.

marcosdumay 1y ago

> it's impossible to not love As an idea, yeah. But if somebody actually tried to build it, the entire world would oppose for very good reasons. Still, it's something that maybe we should build on space (outside of Earth's magnetic field).

randallsquared 1y ago

> Gives everyone something way better to do with all those nuclear bombs The counterpoint there is it gives lots of reasons to make so many more, increasing proliferation worries. However, there's an SF novel that just came out that features nuclear pulse: Fenrir, by Ryk Spoor and (posthumously) Eric Flint. I enjoyed it.

pavel_lishin 1y ago
I should re-read Footfall, by Larry Niven. Quite a few banger lines in there.
- m4rtink 1y ago
  Orion drive is one long line of bangers by definition! ;-)
eszed 1y ago
My favorite SF along those lines is King David's Spaceship, by Jerry Pournelle. https://en.m.wikipedia.org/wiki/King_David%27s_Spaceship https://en.m.wikipedia.org/wiki/King_David%27s_Spaceship
MadnessASAP 1y ago
Yeah, if I'm being really honest, I don't want to give anyone an excuse to put a 1000+ nuclear bombs in orbit. Plus the few dozen you'd have to detonate in quick succession to even get it above the karman line.

PaulHoule 1y ago

The electron beam ignition they talked about doesn't work. Heavy ion probably does https://en.wikipedia.org/wiki/Heavy_ion_fusion https://en.wikipedia.org/wiki/Heavy_ion_fusion but the accelerator needs like 100 barrels that are each 1 km. Maybe you can build a generation starship with that but whatever it is it's going to be big.

hermitcrab 1y ago

I once spoke to Freeman Dyson at a book signing and asked him if Orion would work. He said he thought it would. And I asked him if it should be launched. He said probably not (IIRC due to the amount of radiation that would be put into the atmosphere).

jerf 1y ago
It is almost the epitome of steampunk romance. Launch an entire mid-20th century city and economy into space! And it might even work! But, yeah, you probably don't want to be launching these routinely. People generally badly underestimate the number of nuclear explosions that have been set off on Earth and overestimate the badness of nuclear explosions. Putting one or two of these into orbit might be justifiable. It's certainly not a bad emergency plan to have in your pocket in case of emergencies. But you still certainly wouldn't want an entire industry routinely lighting these things off. Still... the romance of it all...!
- m4rtink 1y ago
  While the Orion drive indeed works perfectly fine in atmosphere - or actually even better than in vacuum - no one says you need to launch them from the ground. While it would be preferable due to the immense weight, you can either lift it by conventional means or possibly build it from local resources in the long run. Once in space Orion is much less problematic & might be even easier to dock and maintain than normal nuclear thermal rockets, where the unshielded reactor will just put out insane amounts or radiation in all directions outside of its shadow shield. Correctly engineered pusher plate should be much easier to deal with.
  - jerf 1y ago
    Having to lift them via some other means first eats away almost all their advantage. However I believe your point holds more generally for nuclear-based space propulsion. That we fear "NUKULAR!" by about two to three orders of magnitude more than is justified has kept us from having halfway decent space travel for at least a good two decades, most likely. There are a number of nuclear propulsion mechanisms that would make things like going to Mars halfway feasible instead of flights of fancy, or doing science missions in months instead of years or even decades, but people hear that you're thinking of lifting nuclear material into space and all rationality goes flying out the launch window. Nuclear is so bad that it basically reaches out through outright magic and guarantees explosions and there's no conceivable amount of preparation that could be done in people's minds to prevent the evil radiation!!!!1! from escaping and eating people's puppies. The funny thing is that even so quite a bit of nuclear material has been lifted into space, but hearing that doesn't make people go "oh, well, maybe it's less dangerous than I thought". I mean, I know this isn't the safest stuff in the world but I sure hope all that anti-nuclear propaganda in the 20th century actually did help prevent nuclear war because it has certainly had massively negative impacts in energy generation, environmental damage, space exploration, and who knows what else.