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Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

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Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#61

Post by smithy44 »

masklinn wrote: post #56
maxerickson wrote: post #54

Earlier quoted context omitted.

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?

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 w…

It's not just the war aspect that makes this un-viable. It's the failure modes, several of which include the destruction of life on earth.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#62

Post by smithy44 »

maxerickson wrote: post #54
DennisP wrote: post #47

Earlier quoted context omitted.

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.

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?

Empress Sato!!

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#63

Post by Pinckney »

Tuna-Fish wrote: post #59
luckystarr wrote: post #41

Nuclear salt-water rockets! https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket Powerful, fast, intriguing and disgusting. :)

Project orion has the name recognition, but nuclear salt water rockets would just be a much better use of the same amount of fissiles. Maybe we should start reposting the wikipedia link every month until people remember mr. Zubrin's creations more than project Orion?

The big advantage of Orion is that we're reasonably confident it would work, and could probably build one within the decade with a serious effort. Zubrin's NSW rocket, on the other hand, falls into the "hasn't yet been conclusively proved impossible" category. We're not sure if we can control the reaction, and we're not sure how much heat would be transferred to the rocket if we can.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#64

Post by maxerickson »

masklinn wrote: post #56
maxerickson wrote: post #54

Earlier quoted context omitted.

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?

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 w…

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.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#65

Post by maverick_iceman »

Symmetry wrote: post #50

I think I like the recent work on pulsed fission-fusion better. Basically you have a normal z-pinch fusion system but surround the fusing hydrogen with U238. It absorbs the fast neutrons from the fusion, fissions, and creates more heat driving the fusion. There's some radioactive waste flying out the nozzle but if you're already in space that's not a huge problem. On the upside, people aren't going to get nervous abo…

What's the Isp of this method?

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#66

Post by JumpCrisscross »

luckystarr wrote: post #41

Nuclear salt-water rockets! https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket Powerful, fast, intriguing and disgusting. :)

An issue with NSWR systems is testing. If you test on the ground, you either eject fissile material into the atmosphere or have to build a very expensive containment and scrubbing system.

These systems may be post orbital assembly technologies.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#67

Post by maverick_iceman »

Tuna-Fish wrote: post #59
luckystarr wrote: post #41

Nuclear salt-water rockets! https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket Powerful, fast, intriguing and disgusting. :)

Project orion has the name recognition, but nuclear salt water rockets would just be a much better use of the same amount of fissiles. Maybe we should start reposting the wikipedia link every month until people remember mr. Zubrin's creations more than project Orion?

Orion would have exhaust velocity ~1000-10000km/s. Compare that to NSWR's 66km/s. NSWR seems fast compared to today's chemical rockets but it's nothing compared to Orion.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#68

Post by maverick_iceman »

andygates wrote: post #33
sillysaurus3 wrote: post #2

Happy to see this getting some attention. It's seemed like one of the only viable propulsion methods for interstellar purposes, though nuclear is unfashionable at the moment. I remember seeing a chart showing that it was possible to reach other stars using a technique like this. Unfortunately the problem is slowing down. You could get there, but you'd be going too fast to stop. And since the more fuel you carry, the…

> 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 cou…

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.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#69

Post by masklinn »

maxerickson wrote: post #64
masklinn wrote: post #56

Earlier quoted context omitted.

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 w…

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.

> 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.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#70

Post by maxerickson »

masklinn wrote: post #69
maxerickson wrote: post #64

Earlier quoted context omitted.

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.

> 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,…

Er… yes?

Sorry, I didn't understand why you were talking about bothering to do that and then crashing it into the atmosphere.

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